New Diagnosis Of Breast Cancer Research Articles

Moving HER2-low breast cancer predictive and prognostic data from clinical trials into the real world.

Background: Previous data, mostly from clinical trials, reported that HER2-low status is associated with low pathological complete response (pCR), and favourable prognosis. Since these findings suggest the existence of an additional breast cancer subtype, we questioned if the predictive/prognostic value of HER2-low was also relevant in the real world. Methods: Data from non-metastatic breast cancer patients treated with neoadjuvant chemotherapy and surgery (2009–2020) were retrieved from our institutional prospectively-maintained registry. Univariable and multivariable logistic models were implemented to study the association between pCR and baseline HER2 status. Univariable analysis of disease-free survival (DFS) was performed through Kaplan-Meier survival curves and log-rank tests. Results: Starting from a total of 790 consecutive cases, we identified 444 newly-diagnosed breast cancer patients featuring HER2 immunohistochemistry (IHC) 0 (HER2-0, n = 109), and 1 + or IHC 2+/in situ hybridization negative (HER2-low, n = 335) receiving anthracycline and taxane-based regimens in 88.9% of cases. Most of the patients were diagnosed with stage II (67.3%) and there was no difference of disease presentation according to HER2-status. pCR was attained by 71 (16.0%) patients and was significantly associated with increased DFS (p = 0.031). Compared to HER2-0, HER2-low cases were more likely hormone receptor-positive (81.2% vs. 43.1%, p < 0.001), well-differentiated (47.5% vs. 26.6%, p = 0.001), less proliferative (21.5% vs. 8.3%, p = 0.001) and less responsive to treatment (pCR 11.6% vs. 29.4%, p < 0.0001). There was no difference in DFS according to HER2 status, though hormone-receptor (HR) negative/HER2-low cases tended to have a worse prognosis compared to HR-negative/HER2-0. By pCR achievement, 3-years DFS was 87.5.% (75.1–100%) vs. 71.6% (65.9–77.8%) (p = 0.161) in HER2-low and 89.1% (75.8–100%) vs. 72.1% (59.7–87.0%) (p = 0.092) in HER2-0. Conclusion: Our real-world data show that HER2-low breast cancer patients represent roughly a half of the cases treated with neoadjuvant therapy, and have poor treatment response. In absence of pCR, HER2-low breast cancer patients have a dismal prognosis, especially when primary tumor hormone receptor status is negative. Studies are therefore needed to define the biology of these tumors for new therapeutic targets and to incorporate HER2-targeting agents in early-stage treatment.

Analysis of Rates of Brain Metastases and Association With Breast Cancer Subtypes in Ontario, Canada

Approximately 1 in 7 patients with metastatic breast cancer (MBC) will receive radiotherapy for brain metastases (BRM). Significant differences in cumulative incidence of BRM by breast cancer subtype may inform future BRM screening protocols. To describe cumulative incidence of BRM among patients with de novo MBC. In this population-based cohort study, population health administrative databases in Ontario, Canada, held at the ICES were used to identify patients diagnosed with de novo MBC between 2009 and 2018. Given that a code for BRM does not exist within ICES, we analyzed the incidence of radiotherapy for BRM. The median (IQR) follow-up was 19.3 (6.2-39.5) months. A total of 100 747 patients with a new diagnosis of breast cancer between January 2009 and December 2018 were identified. Of these patients, 17 955 were excluded because they had previous or subsequent malignant neoplasms, 583 were excluded because they were younger than 18 years, 974 were excluded because there was an invalid Ontario Health Insurance Plan number or a date of death on or before the index date. Among 81 235 remaining patients, 3916 were identified as having de novo MBC. Treatment with radiotherapy for breast cancer BRM. Cumulative incidence of radiotherapy for BRM accounting for the competing risk of death, and time from MBC diagnosis to brain radiotherapy. Kaplan-Meier analyses were performed for time-to-event end points. Logistic regression was used to account for confounding variables. Among 3916 patients with MBC, 1215 (31.0%) had HR-positive/ERBB2 (formerly HER2)-negative cancer, 310 (7.9%) had ERBB2-positive/HR-positive cancer, 200 (5.1%) had ERBB2-positive/HR-negative cancer, 258 (6.6%) had TNBC, and the remaining 1933 patients (49.4%) had an unknown breast cancer subtype. The median (IQR) age at diagnosis was 63 (52-75). A total of 549 (14.0%) underwent stereotactic radiosurgery or whole brain radiotherapy for breast cancer BRM. Cumulative incidence of BRM was higher among patients with ERBB2-positive/HR-negative breast cancer (34.7%), ERBB2-positive/HR-positive breast cancer (28.1%), and triple-negative breast cancer (21.9%) compared to those with HR-positive/ERBB2-negative breast cancer (12.1%). The median (IQR) time from MBC diagnosis to brain radiotherapy ranged from 7.5 (2.3-17.4) months for patients with TNBC to 19.8 (12.2-35.1) months for those with ERBB2-positive/HR-positive breast cancer. Incidence and time to development of BRM vary significantly by breast cancer subtype. A better understanding of the biology of intracranial metastatic disease may help inform potential screening programs or preventative interventions.

Changes in Cancer Screening Rates Following a New Cancer Diagnosis in a Primary Care Patient Panel

Although screenings for breast and colorectal cancer are widely recommended, patient screening rates vary greatly and remain below public health targets, and primary care physicians' (PCPs') counseling and referrals play critical roles in patients' use of cancer screenings. Recent adverse events may influence PCPs' decision-making, but it remains unknown whether cancer screening rates of PCPs' patients change after PCPs are exposed to new cancer diagnoses. To investigate whether PCPs' exposures to patients with new diagnoses of breast or colorectal cancer were associated with changes in screening rates for other patients subsequently visiting the affected PCPs. This cohort study used stacked difference-in-differences analyses of all-payer claims data for New Hampshire and Maine in 2009 to 2015. Participants were PCPs caring for patients. Data analysis was performed from June 2020 to May 2022. New diagnosis of a PCP's patient with breast cancer or colorectal cancer. Patients' breast and colorectal cancer screening rates within 1 year of a PCP visit. The sample included 3158 PCPs (1819 male PCPs [57.6%]) caring for 1 920 189 patients (1 073 408 female patients [55.9%]; mean [SD] age, 41.0 [21.9] years) aged 18 to 64 years. During the study period, 898 PCPs had a patient with a new diagnosis of breast cancer and 370 PCPs had a patient with a new diagnosis of colorectal cancer. In the preexposure period, 68 837 female patients (37.3% of those visiting a PCP) underwent breast cancer screening within 1 year of the visit, and 13 137 patients (10.1% of those visiting a PCP) underwent colorectal cancer screening within 1 year of the visit. For both cancer types, after exposure to a new cancer diagnosis, PCPs' cancer screening rates displayed a rapid, sustained increase. Breast cancer screening rates increased by 4.5 percentage points (95% CI, 3.0-6.1 percentage points; P < .001). Colorectal cancer screening rates increased by 1.3 percentage points (95% CI, 0.3-2.2 percentage points; P = .01). Observed breast cancer screening increases were higher for male PCPs than for female PCPs (3.1 percentage points; 95% CI, 0.4-5.8 percentage points; P = .03). This study found significant, sustained increases in cancer screening rates for patients visiting PCPs recently exposed to new breast and colorectal cancer diagnoses. These findings suggest that PCPs may update practice patterns on the basis of recent patient diagnoses. Future work should assess whether salient cues to PCPs about patient diagnoses when clinically appropriate can improve screening practices.

Lung Nodules Missed in Initial Staging of Breast Cancer Patients in PET/MRI-Clinically Relevant?

Simple SummaryImage-based primary staging in women with newly-diagnosed breast cancer is important to exclude distant metastases, which affect up to 10% of women. The increasing implementation of [18F]FDG-PET/MRI as a radiation-saving primary staging tool bears the risk of missing lung nodules. Thus, chest CT serves as the diagnostic of choice for the detection and classification of pulmonary nodules. The aim of this study was the evaluation of the clinical relevance of missed lung nodules at initial staging of breast cancer patients in [18F]FDG-PET/MRI compared with CT. We demonstrated in an homogeneous population of 152 patients that all patients with newly-diagnosed breast cancer and clinically-relevant lung nodules were detected at initial [18F]FDG-PET/MRI staging. However, due to the lower sensitivity of MRI in detecting lung nodules, a small proportion of clinically-relevant lung nodules were missed. Thus, a supplemental low-dose chest CT after neoadjuvant therapy should be considered for backup.Purpose: The evaluation of the clinical relevance of missed lung nodules at initial staging of breast cancer patients in [18F]FDG-PET/MRI compared with CT. Methods: A total of 152 patients underwent an initial whole-body [18F]FDG-PET/MRI and a thoracoabdominal CT for staging. Presence, size, shape and location for each lung nodule in [18F]FDG-PET/MRI was noted. The reference standard was established by taking initial CT and follow-up imaging into account (a two-step approach) to identify clinically-relevant lung nodules. Patient-based and lesion-based data analysis was performed. Results: No patient with clinically-relevant lung nodules was missed on a patient-based analysis with MRI VIBE, while 1/84 females was missed with MRI HASTE (1%). Lesion-based analysis revealed 4/96 (4%, VIBE) and 8/138 (6%, HASTE) missed clinically-relevant lung nodules. The average size of missed lung nodules was 3.2 mm ± 1.2 mm (VIBE) and 3.6 mm ± 1.4 mm (HASTE) and the predominant location was in the left lower quadrant and close to the hilum. Conclusion: All patients with newly-diagnosed breast cancer and clinically-relevant lung nodules were detected at initial [18F]FDG-PET/MRI staging. However, due to the lower sensitivity in detecting lung nodules, a small proportion of clinically-relevant lung nodules were missed. Thus, supplemental low-dose chest CT after neoadjuvant therapy should be considered for backup.

Abstract 5927: A comparison of the gut microbiome in the context of body mass index in patients with and without breast cancer

Abstract Background: Through diverse interactions with systemic immunosurveillance and metabolism, the gut microbiome is an important factor in the development and treatment of solid tumors including breast cancer (BC). The gut microbiome is also implicated in elevated body mass index (BMI), which is a well-established risk factor for the development of BC. This study determined associations between gut microbiome diversity and BC, adjusting for BMI. Methods: Stool samples were collected from 38 patients with newly-diagnosed BC and 43 age-matched non-cancer controls. Data obtained from 16S rRNA sequencing of fecal samples were clustered into amplicon sequence variants using DADA2. Diversity measures were calculated using vegan and phyloseq, and the statistical differences were compared using t-test or Wilcoxon rank-sum tests. Data were agglomerated at the family level for differential abundance analyses, which were performed with DESeq2. Results: The majority of BC cases observed were stage I (55.26%), hormone-receptor positive (70.97%), and detected during routine screening (68.42%). Mean BMI was greater among patients diagnosed with BC than controls (mean BMI cases: 27.9, controls: 25.23, p=0.04). Alpha diversity measured by the Shannon, Inverse Simpson and Pielou indices was lower in the BC cohort compared with the control cohort (p = 0.02, 0.01, and 0.05, respectively). Beta diversity by non-metric multidimensional scaling on Bray-Curtis distance did not differ between cases and controls (p = 0.74). Five versus seven families and orders were differentially abundant when the analysis was adjusted for BMI versus not, respectively (Table). Conclusion: Differential abundance analysis results differed with and without BMI adjustment, indicating that adjusting for this potentially confounding variable is relevant for BC microbiome studies. BMI should be considered an adjusting variable in studies of the gut microbiome in BC. Negative values for log 2 fold change indicate organisms with greater abundance in controls. Result of DESeq2 analysis without BMI adjustment Family Log 2 Fold Change P adjusted Hungateiclostridiaceae -1.115 0.0034 Enterobacteriaceae 2.925 &amp;lt;0.0001 Fusobacteriaceae 2.043 &amp;lt;0.0001 Lactobacillaceae -1.097 0.0063 Selenomonadaceae 0.985 0.0004 Order Gastranaerophilales -2.653 &amp;lt;0.0001 Flavobacteriales -1.462 0.0002 Result of DESeq2 analysis with BMI adjustment Family Log 2 Fold Change P adjusted Hungateiclostridiaceae -1.273 &amp;lt;0.0001 Enterobacteriaceae 2.379 &amp;lt;0.0001 Selenomonadaceae 1.015 &amp;lt;0.0001 Order Gastranaerophilales -1.838 &amp;lt;0.0001 Flavobacteriales -1.460 &amp;lt;0.0001 Citation Format: Brie Chun, Duygu Altinok Dindar, Keaton Stagaman, Amy Palma, Erin Dahl, Kristin Kasschau, Shaun M. Goodyear, Zahi I. Mitri, Thomas Sharpton, Lisa Karstens, Zhenzhen Zhang. A comparison of the gut microbiome in the context of body mass index in patients with and without breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5927.

Abstract 714: Weight changes between one year before and following breast cancer diagnosis in relation to mTOR protein expression in tumor tissues in the Women’s Circle of Health Study

Abstract Background: Obesity is an important prognostic factor for breast cancer. Aberrant activation of the mechanistic Target of Rapamycin (mTOR) pathway is associated with obesity, cross-sectionally, as well as with breast cancer survival. This study aimed to examine the association of weight change between one year before and following cancer diagnosis with a panel of mTOR protein markers in breast tumors. The study hypothesis was that greater weight gain compared to less or no weight gain would be associated with higher mTOR protein expression in breast tumors. Methods: Study participants were 698 newly-diagnosed breast cancer cases (545 Black women and 153 White women) from the Women’s Circle of Health Study (WCHS). Surgical tissue microarrays were stained for mTOR, phosphorylated mTOR, phosphorylated AKT, and phosphorylated P70S6K using immunohistochemistry. In-home interviews were conducted approximately 10 months after breast cancer diagnosis, and anthropometric measurement was taken by trained staff. Participants reported body weight one year before the diagnosis, excluding the time of pregnancy or nursing. Linear regression analyses were conducted to estimate percent differences in protein expression across quartiles of weight change, adjusting for age, race, BMI one year before diagnosis, menopausal status, history of diabetes, and molecular tumor subtype. Results: Study participants had a mean age of 52.7 (SD = 10.8) years and BMI one year before diagnosis of 30.7 (SD = 6.9) kg/m2. The proportions of participants who had loss ≥5 lbs, loss &amp;lt;5 lbs, no change to gain &amp;lt;5 lbs, and gain ≥5 lbs in weight were 33.7%, 16.2%, 16.2%, and 33.7%, respectively. The fourth vs. first quartile of the weight change was associated with a higher protein expression of mTOR (35.3%, 95% CI = 3.8%, 76.5%), and there was a dose-response pattern (P-trend = 0.0273). No associations were observed between weight change and phosphorylated protein expression. Conclusion: Short-term weight gain before breast cancer diagnosis and following diagnosis may play a role in breast tumor mTOR protein expression. Our findings warrant validation in a study with a prospective measurement of weight gain before breast cancer surgery. Citation Format: Mmadili N. Ilozumba, Angela R. Omilian, Song Yao, Weizhou Zhang, Susmita Datta, Warren Davis, Chi-Chen Hong, Elisa V. Bandera, Thaer Khoury, Christine B. Ambrosone, Ting-Yuan David Cheng. Weight changes between one year before and following breast cancer diagnosis in relation to mTOR protein expression in tumor tissues in the Women’s Circle of Health Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 714.

Abstract 3219: Changes and intra-individual reliability in computed tomography image-assessed adiposity and skeletal muscles areas after breast cancer surgery

Abstract Background: Levels of adiposity and skeletal muscles are prognostic indicators in breast cancer patients; however, data are limited on temporal changes in body composition, particularly in different densities of muscles, before and after mastectomy. Objectives: We examined the change in CT-assessed adipose tissue and different density of skeletal muscle areas using a high-resolution segmentation method in breast cancer patients before and after surgery. Methods: This study included 50 newly-diagnosed breast cancer patients who had taken CT scans before and after surgery. We analyzed their third lumbar (L3) CT images to measure the areas of adipose tissue and five-level (from very-high-density to very-low-density) skeletal muscle components. We assessed mean and percent changes in areas using paired t-test and calculated the intra-class correlation (ICC). Results: Patients’ mean age at diagnosis was 58.3 (SD=12.5) years. The mean duration between scans was 591 (SD=537) days. There was a significant decrease in the areas of subcutaneous adipose tissue (mean change= -36.17 cm2, 11.72% decrease, p=0.029), total adipose tissue (mean change= -45.64 cm2, 10.18% decrease, p=0.032), and very-high-density muscle (mean change= -0.37 cm2, 11.08% decrease, p=0.010). The ratio of total adipose tissue and total skeletal muscle decreased from 3.67 to 3.32 after surgery (mean change= -0.36, 9.81% decrease, p=0.061). There was a strong correlation in adipose tissues and skeletal muscle areas of pre-and post-surgery scans taken within 3 years apart (ICC=0.802 to 0.999, all p&amp;lt;0.05), but the correlations were attenuated in scans taken &amp;gt;3 years apart (ICC = -0.055 to 0.738, all p&amp;gt;0.05). Conclusion: In this sample of breast cancer patients who have undergone surgery, there was a significant decrease in subcutaneous adipose tissues, total adipose tissues, and very-high-density muscle areas over time. Body composition assessed by CT images is reliable for a 3- year period involving breast cancer surgery. These findings serve as a baseline for prospective studies examining the impact of these changes on breast cancer outcomes. Keywords: Adipose tissue, skeletal muscle, computed tomography scans, breast cancer, surgery Citation Format: Livingstone Aduse-Poku, Dheeraj Gopireddy, Mauricio Henandez, Chandana Lall, Joel Divaker, Sara Falzarano, Shahla Masood, Weizhou Zhang, Susmita Datta, Jiang Bian, Ting-Yuan David Cheng. Changes and intra-individual reliability in computed tomography image-assessed adiposity and skeletal muscles areas after breast cancer surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3219.

Autoimmunity to selenoprotein P predicts breast cancer recurrence

BackgroundLow concentrations of serum selenium (Se) and its main transporter selenoprotein P (SELENOP) are associated with a poor prognosis following breast cancer diagnosis. Recently, natural autoantibodies (aAb) with antagonistic properties to SELENOP uptake have been identified in healthy subjects, and in patients with thyroid disease. Given the potential transport disrupting properties, we hypothesized that breast cancer patients with SELENOP-aAb may have a poor prognosis. MethodsSELENOP-aAb along with serum Se, SELENOP and GPX3 activity were determined in serum samples of 1988 patients with a new diagnosis of breast cancer enrolled in the multicentre SCAN-B study. Patients were followed for ∼9 years and multivariate Cox regression models were applied to assess hazard ratios. ResultsApplying a cut-off based on outlier detection, we identified 7.65% of patients with SELENOP-aAb. Autoantibody titres correlated positively to total Se and SELENOP concentrations, but not to GPX3 activity, supporting a negative role of SELENOP-aAb on Se transport. SELENOP-aAb were associated with age, but independent of tumor characteristics. After fully adjusting for potential confounders, SELENOP-aAb were associated with higher recurrence, HR(95%CI) = 1.87(1.17–2.99), particularly in patients with low Se concentrations, HR(95%CI) = 2.16(1.20–3.88). Associations of SELENOP-aAb with recurrence and mortality were linear and dose-dependent, with fully adjusted HR(95%CI) per log increase of 1.25(1.01–1.55) and 1.31(1.13–1.51), respectively. ConclusionOur results indicate a prognostic and pathophysiological relevance of SELENOP-aAb in breast cancer, with potential relevance for other malignancies. Assessment of SELENOP-aAb at time of diagnosis identifies patients with a distinctly elevated risk for a poor prognosis, independent of established prognostic factors, who may respond favourably to Se supplementation.

Abstract P5-14-03: National claims data analysis of breast cancer diagnosis and treatment before versus during the COVID-19 pandemic

Abstract Background: The COVID-19 pandemic imposed great burden on the healthcare system and required patients and their physicians to make unprecedented choices about cancer care. Hospital-based retrospective reviews suggested changes in breast cancer management during 2020 compared to previous years, including greater use of preoperative therapy. We used insurance claims data to understand the impact of the pandemic on breast cancer diagnosis and treatment at a national level. Methods: We identified new diagnoses of breast cancer from 2017-2020 in the Optum data set, consisting of claims records linked to electronic health records. The overall population (enrolled in Optum for at least 6 months with at least one diagnosis of any condition and no prior breast cancer diagnosis) included an average of 8 million adult Americans per year. A breast cancer diagnosis was defined as a first-ever ICD code for breast cancer with a breast diagnostic biopsy procedure code (considered the cancer diagnosis date) within 6 months before to 3 months after that ICD code. Each year’s cohort of breast cancer cases was limited to those diagnosed between February 1 and May 30, with follow-up through June 30 of the diagnosis year. First treatment after diagnosis was classified as either endocrine therapy, chemotherapy, or surgery. Geographic area was defined by the 9 Census Bureau regions. We used a Poisson regression to compare the rate of breast cancer diagnosis in 2020 versus 2017-2019 and a Chi-squared test to compare the distributions of first treatment. To investigate differences in the impact of the pandemic on rate of diagnosis (Poisson regression) or use of preoperative therapy (logistic regression) by race/ethnicity, income, or geographic area, we included each of these covariates as well as its interaction with year (2020 vs 2017-2019) in separate models. Results: There were 2,841 breast cancer diagnoses February-May 2020 (0.037% of overall population), compared to 3,880 in 2019 (0.045%), 3,509 in 2018 (0.043%), and 2,999 in 2017 (0.041%). In 2020 compared to 2017-2019, new breast cancer diagnoses decreased by 12.3% (95% CI 8.6%-15.9%; p &amp;lt; 0.0001). No significant differences were observed in this reduction in diagnoses by race/ethnicity, income level, or geographic area. Median date of diagnosis was earlier in 2020 (March 11) compared to 2017-2019 (March 29-April 1), a result of the diagnosis rate dropping more in later months. Among patients who received treatment during follow-up (83.1% in 2017-2019 vs 86.2% in 2020, a difference likely reflecting this shift in diagnosis date), there was a marked reduction in surgery as first treatment in 2020 compared to previous years (88.7% in 2017-2019 vs 69.3% in 2020), while both preoperative chemotherapy (6.1% in 2017-2019 vs 10.7% in 2020) and preoperative endocrine therapy (5.2% in 2017-2019 vs 20.1% in 2020) increased (p &amp;lt; 0.0001). There were no differences in the shift toward preoperative therapy by race/ethnicity or income, but there was a significant difference by geographic area (p=0.0003): the Mountain region had the least change in use of preoperative therapy (odds ratio 2.46 [95% CI 1.75-3.47] of preoperative therapy during vs before the pandemic) while the Middle Atlantic region had the greatest (odds ratio 5.64 [95% CI 3.79-8.38]). Conclusions: Among insured U.S. patients, new breast cancer diagnoses decreased by 12.3% during February-May 2020 compared to the same period in the previous three years, and use of preoperative therapy, largely endocrine, increased by 2.7-fold. The impact of the pandemic on choice of first treatment differed by geographic area, but not by race/ethnicity or income in this insured population. We will monitor with continued follow-up of claims data to assess the longer-term impact of these pandemic-related changes on treatment patterns, cost, and patient outcomes. Citation Format: Jennifer L Caswell-Jin, Maryam N Shafaee, Lan Xiao, Mina Liu, Natasha Purington, Esther M John, Melissa L Bondy, Allison W Kurian. National claims data analysis of breast cancer diagnosis and treatment before versus during the COVID-19 pandemic [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-14-03.

Abstract P5-14-01: National claims data analysis of breast cancer diagnosis and treatment before versus during the COVID-19 pandemic

Abstract Background: The COVID-19 pandemic imposed great burden on the healthcare system and has required patients and their physicians to make unprecedented choices about cancer care. Hospital-based retrospective reviews have suggested changes in breast cancer management during 2020 compared to previous years, including greater use of preoperative therapy. We used insurance claims data to understand the impact of the pandemic on breast cancer diagnosis and treatment at a national level. Methods: We identified new diagnoses of breast cancer from 2017-2020 in the Optum Clinformatics claims data set, consisting of claims records linked to electronic health records. The overall population (enrolled in Optum for at least 6 months with at least one diagnosis of any condition and no prior breast cancer diagnosis) included an average of 8 million adult Americans per year. A new breast cancer diagnosis was defined as a first-ever ICD code for breast cancer with a breast diagnostic biopsy procedure code (considered the cancer diagnosis date) within 6 months before to 3 months after that ICD code. Each year’s cohort of breast cancer cases was limited to those diagnosed between February 1 and May 30, with follow-up through June 30 of the diagnosis year. First treatment after diagnosis was classified as either endocrine therapy, chemotherapy, or surgery. Geographic area was defined by the 9 Census Bureau regions. We used a Poisson regression to compare the rate of breast cancer diagnosis in 2020 compared to 2017-2019 and a Chi-squared test to compare the distribution of first treatment in 2020 compared to 2017-2019. To investigate differences in the impact of the pandemic on rate of diagnosis (Poisson regression) or use of preoperative therapy (logistic regression) by race/ethnicity, income, or geographic area, we included each of these covariates as well as its interaction with year (2020 vs 2017-2019) in separate models. Results: There were 2,841 breast cancer diagnoses February-May 2020 (0.037% of overall population), compared to 3,880 in 2019 (0.045%), 3,509 in 2018 (0.043%), and 2,999 in 2017 (0.041%). In 2020 compared to 2017-2019, new breast cancer diagnoses decreased by 12.3% (95% CI 8.6%-15.9%; p &amp;lt; 0.0001). No significant differences were observed in this reduction in diagnoses by race/ethnicity, income level, or geographic area. Median date of diagnosis was earlier in 2020 (March 11) compared to 2017-2019 (March 29, April 1, and April 1 respectively), a result of a larger drop in diagnoses later in the time interval in 2020. Among patients who received treatment during follow-up (83.1% in 2017-2019 vs 86.2% in 2020, a difference likely reflecting this shift in diagnosis date), there was a marked reduction in surgery as first treatment in 2020 compared to previous years (88.7% in 2017-2019 vs 69.3% in 2020), while both preoperative chemotherapy (6.1% in 2017-2019 vs 10.7% in 2020) and preoperative endocrine therapy (5.2% in 2017-2019 vs 20.1% in 2020) increased (p &amp;lt; 0.0001). There were no differences in the shift toward preoperative therapy by race/ethnicity or income, but there was a significant difference by geographic area (p=0.0003): the Mountain region had least change in use of preoperative therapy (odds ratio 2.46 [95% CI 1.75-3.47] of preoperative therapy during vs before the pandmic) while the Middle Atlantic region had the greatest (odds ratio 5.64 [95% CI 3.79-8.38]). Conclusions: Among insured U.S. patients, new breast cancer diagnoses decreased by 12.3% during February-May 2020 compared to the same period in the previous three years, and use of preoperative therapy, largely endocrine, increased by 2.7-fold. The impact of the pandemic on choice of first treatment differed by geographic area, but not by race/ethnicity or income in this insured population. We will monitor with continued follow-up of claims data to assess the longer-term impact of these pandemic-related changes on treatment patterns, cost, and patient outcomes. Citation Format: Jennifer L Caswell-Jin, Maryam N Shafaee, Lan Xiao, Mina Liu, Natasha Purington, Esther M John, Melissa L Bondy, Allison W Kurian. National claims data analysis of breast cancer diagnosis and treatment before versus during the COVID-19 pandemic [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-14-01.

Abstract P4-11-03: Decisions and outcomes of young women with breast cancer regarding fertility preservation before cancer treatment and family building after treatment

Abstract Background: More than 12,000 new diagnoses of breast cancer occur annually in women &amp;lt;40 years old and most will become survivors. It is recommended that young women with breast cancer be counseled about fertility preservation (FP) options prior to initiation of systemic therapy if they are interested in having biologic children in the future. Decisions to pursue FP are multifactorial and current data suggest only a small proportion of women pursue FP before breast cancer treatment. This study examines the decisions and outcomes of women who pursue FP before treatment and family building after therapy. Methods: An IRB approved web-based cross-sectional survey examining decisions about FP, factors influencing decisions, and post-decision regret was administered to young (age 18-45) breast cancer survivors with stage I-III breast cancer who were either English or Spanish speaking. All women received counseling by a MSK Fertility Nurse Specialist prior to initiating cancer treatment at MSKCC in 2009-2017. Clinical data was also extracted from the medical record .Results: Our sample consisted of 211 women with a mean and median age of 34 (age range was 20-45) and 82% had ER+ disease, 19% had HER-2+ disease and 12% had triple negative breast cancer. At the time of diagnosis, 46 women (22%) had children and 173 women (61%) were married or living with a partner. 151 (72%) of study participants wanted to have (more) children, 48 (23%) were unsure and 12 (6%) did not want additional children. Prior to treatment, 172 (82%) women met with a reproductive endocrinologist (RE), and 122 (58%) underwent FP: 73 froze eggs and 49 froze embryos. After treatment, 28 (13%) women met with a RE, and 13 underwent FP: 9 froze eggs and 4 froze embryos. 26 (12%) patients opted to just use a GnRH agonist during chemotherapy. For women who froze eggs, the average number obtained was 14 pre-treatment and 18 post-treatment. Of those who froze embryos, the average number obtained was 7 both pre- and post-treatment. Concern with financial burden was noted in 58% of women. Insurance did not cover any FP treatment for 56/122 (46%) of women. 32% (39/122) of women paid $10,000 or more for their FP. Women reported that the most important factor that contributed to their FP decision was the ability to feel hopeful about their future followed by concern that they would have regrets if they did not undergo FP. Additional factors that contributed to the FP decision were the desire to have biologic children, feeling overwhelmed by the cancer diagnosis, the cost of freezing eggs or embryos and concern about taking hormone medication. Reflecting back 176 women (83%) believe they made the right decision regarding FP. After completing primary breast cancer treatment, 61 women (29%) opted to try to build their family and 42 had children: 35 gave birth and 7 used a surrogate. Currently 3 women are pregnant, and 10 are pursuing pregnancy. 19 (31%) women conceived without fertility treatment and 22 (36%) women used or are currently pursuing assisted reproduction. 1 woman used a donor egg and 15 successfully used frozen eggs/embryos harvested prior to treatment. Delay of endocrine therapy to pursue pregnancy was uncommon, reported by only 6 women. However, 23 women interrupted endocrine therapy to conceive. Conclusions: The majority of women who attempted family building after treatment were able to have children. Many of these women used eggs/embryos frozen before breast cancer treatment either by getting pregnant themselves or via surrogacy. These data stress the importance of early discussion with a fertility nurse specialist regarding risks and preservation options followed by prompt referral to a reproductive endocrinologist. In addition, FP helped women to feel hopeful about their future and the majority of women believe they made the right decision. Citation Format: Shari B Goldfarb, Bridgette Thom, Cassandra Chang, Nadia Abdo, Andrea Carpio, Rosemary Semler, Catherine Benedict, Patricia Hershberger, Joanne F Kelvin, Mary L Gemignani. Decisions and outcomes of young women with breast cancer regarding fertility preservation before cancer treatment and family building after treatment [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-11-03.

Abstract P2-09-15: Frequency of germline mutations in breast cancer susceptibility genes among women under age 50 presenting with parity associated breast cancer

Abstract Background: Epidemiologic data have demonstrated an increased risk of breast cancer development following pregnancy which can last up to 10 years, particularly in women with older age at childbirth. The majority of women with parity associated breast cancer (PABC) undergo genetic testing based on their young age at onset, per current NCCN guidelines. Prior studies have evaluated the interaction of parity and germline BRCA1/2 mutation status, but these have not been extended to other pathogenic germline mutations in known breast cancer susceptibility genes (PALB2, TP53, PTEN, CDH1, CHEK2, ATM, and STK11). Our goal was to evaluate the prevalence of pathogenic germline mutations in a contemporary cohort of women less than 50 diagnosed with breast cancer in relation to their parity status and the time since their most recent pregnancy. Methods: The Northwestern Electronic Database Warehouse was queried for women diagnosed with a new breast cancer between 2010 - 2020 at the age of less than 50 and underwent genetic testing with results available. Patient demographic data, parity history, and genetic testing results were obtained from the structured electronic health records data as well as from semi-structured clinical notes using rule-based text mining methods. 929 women were identified with complete information on parity status, age at first birth, age at most recent birth, breastfeeding status, and germline mutation status. Statistical analyses included Pearson’s chi-square and logistic regression with adjustment for age at diagnosis. Results: 85 women (9.1%) had a germline genetic mutation, with the most prevalent mutations being BRCA1 (3.9%), BRCA2 (2.5%), CHEK2 (0.8%), PALB2 (0.6%) and ATM (0.5%). 90 women (9.7%) had a variant of uncertain significance (VUS) and were included in the no mutation group for analysis. There was no statistically significant difference between nulliparous and parous women in regard to likelihood of having a pathogenic germline genetic mutation (age-adjusted OR 0.85, CI 0.53 -1.29). Among parous women stratified by recency of pregnancy (&amp;lt;5 years, 5-10 years, and &amp;gt;10 years), there was an increased likelihood of having a germline genetic mutation with recency of pregnancy &amp;lt; 5 years (age adjusted OR 2.2, CI 1.07-3.75) compared to women with &amp;gt; 10 years since last pregnancy. Evaluation of each separate germline mutation demonstrated mixed results with CHEK2 mutations more likely with more recent pregnancy (age adjusted OR 3.58, CI 1.13 - 7.57), while PALB2 mutations were less likely with more recent pregnancy (age adjusted OR 0.72, CI 0.52-0.85). The remainder of the mutations were not statistically significantly different among nulliparous vs parous women or when stratified by recency of pregnancy. Conclusions: Nulliparous women with a new diagnosis of breast cancer under the age of 50 were equally as likely to have a germline genetic mutation compared to parous women. After adjusting for age, recency of pregnancy within 5 years of breast cancer diagnosis was associated with increased likelihood of having a germline genetic mutation. The influence of family history of cancer will be addressed in additional analyses. Our data suggest that these mutations may confer an increased risk of parity-associated breast cancer, but need confirmation in larger studies. Citation Format: Erica Wrubel, Saya Rene Dennis, Takahiro Tsukioki, Theresa Sciaraffa, Yuan Luo, Seema A Khan. Frequency of germline mutations in breast cancer susceptibility genes among women under age 50 presenting with parity associated breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-09-15.

Altered Expression Levels of MicroRNA-155 and SOCS-1 in Peripheral Blood Mononuclear Cells of Newly Diagnosed Breast Cancer Patients

MicroRNA-155 (miR-155) has a critical role in pro-inflammatory activation and tumor progression. In addition, miR-155 has various oncogenic effects in the tumor microenvironment by targeting the suppressor gene of cytokine signaling-1(SOCS-1) and interleukin-6 (IL-6). This study investigated the association of inflammatory changes with the variations of miR-155 expression in newly diagnosed breast cancer (NDBC) patients. Seventy NDBC patients were categorized as lobular and ductal subgroups and forty healthy individuals participated in this study. The expression rate of miR-155 and its downstream target gene, SOCS-1, as well as the plasma levels of IL-6, were evaluated in peripheral blood mononuclear cells of NDBC patients; using real-time PCR and enzyme-linked immunosorbent assay, respectively. Our results indicated an over-expression of miR-155 in the PBMCs of NDBC patients which was significantly associated with the tumor grade and the type of ductal carcinoma. In contrast, a significant downregulation of SOCS-1 was observed in NDBC patients compared to control group, however, there was no significant difference between two subtypes of BC. Furthermore, a higher concentration of plasma IL-6 was detected in NDBC patients compared to the healthy control group which had an inverse correlation with the SOCS-1 levels. According to the potential effects of miR-155 on regulating the expression of SOCS-1 and IL-6, we suggest this small transcript as a promising diagnostic marker for various types of BC patients.

Anthracycline chemotherapy and its effects on left ventricular mechanics: insights into the PROACT PLUS study

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): South Tees Research and Development Fund Background Anthracyclines continue to form the backbone of chemotherapy treatment for breast cancer and lymphoma. However, their use has been directly associated with dose-dependent cardiotoxicity. Most studies to date have focused on the effects of high dose anthracyclines on left ventricular (LV) systolic function with a particular interest in peak global longitudinal strain (GLS). Not much attention has been directed to the effects of lower dose anthracyclines and other strain parameters of LV systolic and diastolic function. Purpose In this prospective study, we performed a comprehensive 2-dimensional echocardiographic assessment on the effects of anthracyclines on both the LV systolic and diastolic strain measures. We focused on the changes in the LV end-systolic (ES) GLS, myocardial GLS (myoGLS), global radial strain (GRS), global circumferential strain (GCS), myocardial GCS (myoGCS), twist and torsion. Additionally, peak systolic (PS), ES, early-diastolic (ED), and late-diastolic (LD) strain-rates were measured. Methods Patients with a new diagnosis of breast cancer or lymphoma undergoing anthracycline chemotherapy (any dose) were recruited between October 2018 to March 2020. Echocardiograms were performed pre-chemotherapy (V1) and 1 month post treatment (V2). These were analysed offline using vendor-independent software (TomTec 2D CPA). The study was ethically approved by the Health Research Association (REC reference 18/EM/0177). Results A total number of 62 were recruited into the study of which 7 patients passed away during treatment and 5 failed to attend their follow-up appointment at V2. Of the remaining patients, 6 dropped their LV ejection fraction (EF) to &amp;lt; 53% at V2 (G1). In these patients, a significant reduction in the LV ES-GLS (-19.3% vs. -15.3%, p = 0.0041), myoGLS (-16.8% vs. -12.8%, p = 0.0014), LV longitudinal PS strain-rate (-1 1/s vs. 0.78 1/s, p = 0.0063), and LV longitudinal ED strain-rate (1.1 1/s vs. 0.67 1/s, p = 0.026) was seen from V1 to V2. There was no statistically significant change in the other systolic and diastolic strain parameters in this group of patients. In patients with a normal EF at V2 (G2), a reduction in the LV ES-GLS (-20.8% vs. -19.9%, p = 0.013) and myoGLS (-17.9% vs. -16.9%, p = 0.012) was also seen from V1 to V2. Additionally, a deterioration in the LV radial ED strain-rate (-1.37 1/s vs. -1.2 1/s, p = 0.009), LV longitudinal ED strain-rate (0.98 1/s vs. 0.85 1/s, p = 0.01), and LV circumferential ED strain rate (1.62 1/s vs. 1.33 1/s, p = 0.045) was observed. Conclusion In G1, a more extensive deterioration (&amp;gt;15%) in the LV ES-GLS, myoGLS, and longitudinal ED strain-rate was evident when compared to G2. The additional reduction in LV early diastolic strain-rate in both patient groups highlights the global insult that anthracyclines can pose on both LV systolic and diastolic function. However, whether these findings translate into future development of cardiotoxicity is not yet known.

Interval breast cancer information dissemination and action during COVID period

Background: Despite Public Health England guidance on interval breast cancer (where a patient with new diagnosis of breast cancer was reported to have a normal screening mammogram within last 3 years or normal family history screening mammogram within last 1 year), there has been no uniform policy in place locally. An initial local assessment in June 2019 showed an incidence of 31 interval breast cancers over a 12-month period. Introduction of interval breast cancer pathway, aiming for 100% improvement in dissemination of information, recording of data, and subsequent actions.

MRI of the Lactating Breast: Computer-Aided Diagnosis False Positive Rates and Background Parenchymal Enhancement Kinetic Features

To investigate the application of computer-added diagnosis (CAD) in dynamic contrast-enhanced (DCE) MRI of the healthy lactating breast, focusing on false-positive rates and background parenchymal enhancement (BPE) coloring patterns in comparison with breast cancer features in non-lactating patients. The study population was composed of 58 healthy lactating patients and control groups of 113 healthy premenopausal non-lactating patients and 55 premenopausal non-lactating patients with newly-diagnosed breast cancer. Patients were scanned on 1.5-T MRI using conventional DCE protocol. A retrospective analysis of DCE-derived CAD properties was conducted using a commercial software that is regularly utilized in our routine radiological work-up. Qualitative morphological characterization and automatically-obtained quantitative parametric measurements of the BPE-induced CAD coloring were categorized and subgroups' trends and differences between the lactating and cancer cohorts were statistically assessed. CAD false-positive coloring was found in the majority of lactating cases (87%). Lactation BPE coloring was characteristically non-mass enhancement (NME)-like shaped (87%), bilateral (79%) and symmetric (64%), whereas, unilateral coloring was associated with prior irradiation (p <0.0001). Inter-individual variability in CAD appearance of both scoring-grade and kinetic-curve dominance was found among the lactating cohort. When compared with healthy non-lactating controls, CAD false positive probability was significantly increased [Odds ratio 40.2, p <0001], while in comparison with the breast cancer cohort, CAD features were mostly inconclusive, even though increased size parameters were significantly associated with lactation-BPE (p <0.00001). BPE was identified as a common source for false-positive CAD coloring on breast DCE-MRI among lactating population. Despite several typical characteristics, overlapping features with breast malignancy warrant a careful evaluation and clinical correlation in all cases with suspected lactation induced CAD coloring.

Effects of COVID-19 pandemic in a breast unit: Is it possible to avoid delays in surgical treatment?

BackgroundCoronavirus disease 2019 (COVID‐19) pandemic has caused fear all around the world. With people avoiding hospitals, there has been a significant decrease in outpatient clinics. In this study, we aimed to compare and explore the first peak of the pandemic period by studying its effects on patient applications, new diagnoses and treatment approaches in a non‐infected hospital.MethodsWe collected data from the first peak of the pandemic period in Turkey, from the pandemic declaration (11 March 2020) to social normalization (1 June 2020), and compared it with the data from a pre‐pandemic period with a similar length of time. We analyzed the data of breast cancer patients from application to surgery.ResultsThe data of 34 577 patients were analyzed for this study. The number of patients who applied to outpatient clinics decreased significantly during the pandemic period. After excluding control patients and benign disorders, a figure was reached for the number of patients who had a new diagnosis of breast cancer (146 vs. 250), were referred to neoadjuvant treatment (18 vs. 34), and were treated with surgery (121 vs. 229). All numbers decreased during the pandemic period, except for surgeries after neoadjuvant treatment (21 vs. 25). Surgical treatment approaches also changed. However, the rate of newly diagnosed breast cancer patients treated with surgery was similar in both periods. None of these patients were diagnosed with COVID‐19 or died during the pandemic.ConclusionThis study shows that non‐infected hospitals can be useful in avoiding delays in the surgical treatment of cancer patients.

1628P Impact of COVID-19 pandemia on the diagnosis of breast cancer in one region of north of Portugal: One year experience

Background: The onset of COVID-19 pandemic forced lockdown and halted breast cancer screening programs. We aimed to investigate the impact of COVID-19 on the new diagnosis and staging of breast cancer. Methods: In this cohort study, we included all patient with new diagnosis of breast cancer who were admitted to our Hospital (Hospital Pedro Hispano, Matosinhos, Portugal), between March 2019 and March 2021. We collected data on baseline clinical conditions such as age, stage at diagnosis and treatment. We created two different groups were created: 1st group- before COVID-19 pandemia (March 1, 2019 to March 16, 2020);2nd group - COVID-19 pandemia (March 17, 2020 to March 31, 2021). A comparative assessment between groups was carried out. Results: Were included 483 patients;n=289 in the 1st group and n= 194 in the 2nd group. The median age was 60 years old in the 1st group and 59 years old in the 2nd group. In the 1st group, 13% patients were diagnosis with ductal in situ carcinoma (DCIS), 51% in stage I, 24% in stage II, 9.5% in stage III and 3% in stage IV. In 2nd group, 9% had DCIS, 30% were in stage I, 40% in stage II, 11% in stage III and 10% in stage IV. Stage at diagnosis was significantly higher in the 2nd group (p< 0.001) This situation was mainly due to tumour size (T). In the 1st group, most patients (n=91;38%) had tumour size between 10 e 20mm (T1c in TNM classification). One the other hand, 40% (n=78) of patients included in the 2nd group had tumour size between 20 e 50mm (T2), with significant differences between them (p=0.004). No difference was found between groups in nodular involvement (p=0.189), with the majority of patients (∼50% in both groups) presenting without nodular involvement (N0 in TMN classification). 10% of patients in 2nd group and 3% in 1st group had metastatic disease at diagnosis, with differences between them (p=0.006). 49% (n=119) of patients in 1st group and 52% (n=100) in the 2nd group were treated with chemotherapy, without differences between those groups. Conclusions: Our results show that during one year after COVID-19 pandemia the incidence of breast cancer decreased, and patients were diagnosis in more advanced stages. This situation could have been related to patient referral to non COVID-19 Hospitals or correspond to a true sub-diagnosis. Legal entity responsible for the study: M. Vilaca. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.

Abstract 92: Clinical Care and Short-Term Survival Outcomes for Women with Breast Cancer in Gaza, Occupied Palestinian Territory

Abstract Purpose: We aimed to provide robust breast cancer survival estimates for Palestinian women in Gaza, and to identify interventions necessary to improve care in this setting. Methods: We collected detailed clinical and treatment data from the medical records of all women diagnosed with breast cancer from Jan 1, 2017 to Dec 31, 2018 in Gaza. Semi-structured interviews with 11 healthcare providers and 20 patients diagnosed during this period were conducted to examine experiences of giving and receiving cancer care. Women were followed using clinical and death records until 31 December 2019. The one-year crude survival rate was estimated using the Kaplan-Meier method. Results: 524 new diagnoses of breast cancer (mean age:53, range:23-100) were recorded during the study period, giving a crude annual incidence rate of 27 per 100,000 population. Key prognostic factors were available in most cases -stage (93%), ER, PR, HER2 (82%) and slightly less often for tumour grade (77%) and tumour size (70%). 51% of women underwent mastectomy. By December 31, 2019 24 (5%) of these women had died. The total estimated mean time until death was 11·7 months, and the one-year crude survival rate was 95·4%. Many women reported lack of treatment as the main barrier to effective cancer care, especially those receiving Gosorelin or radiotherapy. This issue was also cited by oncologists who described the difficulty of adhering to treatment protocols for early-stage breast cancer because of radiotherapy not being available in Gaza. Regarding diagnosis, delays were observed in the macroscopic examination of biopsies due to lack of staff, and a severe shortage of immunohistopathology staining kits hindered treatment planning. Conclusion: Lack of hospital facilities for diagnosis and treatment are barriers to effective cancer care in Gaza. Despite major challenges, Palestinian women with breast cancer have a high short-term survival. Citation Format: Shaymaa Alwaheidi, Professor Richard Sullivan, Dr Elizabeth Davies. Clinical Care and Short-Term Survival Outcomes for Women with Breast Cancer in Gaza, Occupied Palestinian Territory [abstract]. In: Proceedings of the 9th Annual Symposium on Global Cancer Research; Global Cancer Research and Control: Looking Back and Charting a Path Forward; 2021 Mar 10-11. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2021;30(7 Suppl):Abstract nr 92.

Abstract 869: Breast tumor gene expression in the mTOR pathway and clinicopathological characteristics in Black women and White women

Abstract Background: Aberrant activation of the mammalian Target of Rapamycin (mTOR) pathway is implicated in breast carcinogenesis and outcomes. Based on protein expression data, the activation could be heterogeneous by race, body fatness, and tumor clinicopathological characteristics. To understand potential impacts of mTOR pathway signaling in breast cancer, we evaluated the association of race and clinicopathological characteristics with gene expression of select mTOR pathway genes in breast tumors. Methods: Study participants were from the Women's Circle of Health Study (WCHS), complemented with samples from the Roswell Park Pathology Network Shared Resource (PNSR). Tumor tissue blocks were collected from 367 newly-diagnosed breast cancer cases (190 Black and 177 White women). Gene expressions of AKT1, EIF4EBP1, MTOR, RPS6KB2, TSC1 were quantitated using NanoString assays. Generalized linear models were performed to relate gene expression levels with demographic and clinicopathological variables. The regression coefficient (β) was converted to percentage difference. Additionally, we conducted an external validation of mTOR gene expression using data from The Cancer Genome Atlas (TCGA; N=332). Results: Study participants were mostly within the ages of 51 to 65 years old. Black women had lower expression levels of AKT1, MTOR, RPS6KB2 and TSC1 compared to White women. Black race vs White race was significantly associated with lower gene expression of AKT1 (-21.34%, 95% CI = -31.61%, -8.61%) and RPS6KB2 (-12.19%, 95% CI = -19.75%, -3.92%). The racial differences in expression levels of these two genes were consistent across luminal A, luminal B, HER2-enriched, and triple-negative subtypes. Higher tumor grade was associated with higher expression levels of EIF4EBP1 and RPS6KB2, but with lower expression of TSC1. In comparison to luminal A tumors, luminal B tumors had higher expression of RPS6KB2 (17.35%, 95% CI = 4.08%, 32.31%); whereas HER2-enriched (-23.66%, 95% CI= -41.73%, -1.00%) and triple-negative (-22.89%, 95% CI= -40.55%, -1.00%) had lower expression of TSC1. All these associations were unchanged after additionally adjusting for body mass index in a subset. Similarly, results from the TCGA data showed that in comparison to luminal A tumors, luminal B tumors had higher expression of RPS6KB2 (53.73%, 95% CI = 27.12%, 87.76%) whereas HER2-enriched had a lower expression of TSC1 (-26.66%, 95% CI = -43.45%, -4.88%) and triple-negative subtype had a lower expression of TSC1 (-17.30%, 95% CI = -50.68%, -3.05%). Conclusions: Variables such as race and breast cancer subtypes should be considered in studying the mTOR pathway genes in breast cancer tumors. Citation Format: Mmadili N. Ilozumba, Song Yao, Adana A. Llanos, Angela Omilian, Weizhou Zhang, Susmita Datta, Chi-Chen Hong, Warren Davis, Thaer Khoury, Christine B. Ambrosone, Ting-Yuan D. Cheng. Breast tumor gene expression in the mTOR pathway and clinicopathological characteristics in Black women and White women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 869.