Rare Subtype Of Breast Cancer Research Articles

Solid-basaloid Variant of Mammary Adenoid Cystic Carcinoma – Report of an Unusual Case with Literature Review

Abstract Introduction/Objective Adenoid cystic carcinoma (AdCC) of breast is a rare subtype of malignancy, constituting approximately 0.1% of all breast carcinomas. The solid-basaloid variant (SB-AdCC) is exceedingly uncommon. Here, we present such an unusual case of SB-AdCC. Methods/Case Report A 64-year-old woman who underwent screening mammography presented with abnormal findings, revealing a hypoechoic ovoid, lobulated nodule at 7:00 of the left breast, which prompted an ultrasound- guided biopsy. Histologically, the biopsy cores demonstrated a 9 mm infiltrative round, solid nests with focal “cribriforming” areas. It was composed of monomorphic basaloid epithelial cells with marked nuclear atypia and high mitotic count. High-grade ductal carcinoma in situ, solid papillary carcinoma, and nonspecific invasive carcinoma were in differentials. Immunohistochemical (IHC) staining expressed positivity for CD117 and CK 5/6, while p63, SMMHC, and synaptophysin were negative. MYB gene rearrangement confirmed by fluorescence in situ hybridization. As expected, the tumor lacked ER, PR, and HER2 expression by IHC. Left breast mastectomy and axillary lymph node dissection have been scheduled. Results (if a Case Study enter NA) NA Conclusion Per literature review, the mean age of SB-AdCC at diagnosis was 68 years (33-84 years) with an average tumor size of 25 mm (12-70 mm). It had more aggressive behavior, with a higher propensity for lymph node metastasis, locally recurrence, and distant metastasis. The median disease-free survival was 46.5 months versus 151.8 months in those with class AdCC. Notably, neovascularization has emerged as a strong independent predictor of outcome in SB-AdCC. Most patients were treated with surgical excision, axillary lymph node dissection, and/or adjuvant chemotherapy. Limited studies demonstrated that neoadjuvant chemotherapy may induce an excellent response. Furthermore, a distinct molecular mutation enriched in NOTCH and CREBBP genes has been identified, which could be novel potential therapeutic target. Thus, awareness of this extremely rare breast cancer subtype and accurate differentiation from other entities are paramount for appropriate management strategies.

Invasive Micropapillary Carcinoma of the Breast: Comparison of Clinical, Epidemiological, Anatomopathological and Therapeutic Features with Infiltrating Carcinoma of Non-Specific Type

Invasive micropapillary carcinoma (IMCC) is a rare histological subtype of invasive breast cancer, its frequency ranges from 1.0 to 8.4% of all breast cancer cases. It is identified as a particularly aggressive tumor since frequent invasion of vessels, skin and lymph nodes is often reported. The aim of the work is to describe and compare the epidemiological, clinical, anatomopathological and molecular aspects of CMPI compared to CINS. Compare the overall survival of the two groups in order to identify the prognostic factors for CMPI. This is a retrospective, descriptive and analytical study spread over 6 years from January 2015 to December 2020, involving all cases of CMPI and CINS of the breast collected at the Obstetrics and Gynecology department of the Maternity and Neonatology Center of Monastir. The frequency found was 5.5% for CMPI and 72.69% for CINS. In our series we found the average age to be more advanced in CINS compared to CMPI without having a statistically significant difference (p=0.49). CMPI tends to be slightly larger than CINS with an average size of 3.7 compared to 3 for CINS. The right breast was the predominant tumor site for the 2 types of cancer p=0.71. CMPI presents a higher frequency of locoregional ADP and vascular emboli with p=0.001. Distant metastases were more frequent in CINS but without having a statistically significant difference. The overall survival of CMPI is 76% versus 86.4%. % of CINS. CMPI represents a particular variety of breast carcinomas; in this study we tried to dissect its different epidemiological, clinical, radiological and therapeutic characteristics which were largely in agreement with the literature.

Primary Squamous Cell Carcinoma of the Breast With 18 F-FDG PET/CT.

A 67-year-old woman presented with a palpable breast mass. A biopsy was taken, and the diagnosis was squamous cell carcinoma. Primary squamous cell carcinoma of breast is an extremely rare subtype of invasive breast cancer. The diagnosis requires ruling out metastasis of other sites and that is not skin origin. The patient was referred to 18 F-FDG PET/CT for diagnosis and staging. In this report, we present PET/CT and postsurgical pathology findings.

Predictive model of prognosis index for invasive micropapillary carcinoma of the breast based on machine learning: a SEER population-based study

BackgroundInvasive micropapillary carcinoma (IMPC) is a rare subtype of breast cancer. Its epidemiological features, treatment principles, and prognostic factors remain controversial.ObjectiveThis study aimed to develop an improved machine learning-based model to predict the prognosis of patients with invasive micropapillary carcinoma.MethodsA total of 1123 patients diagnosed with IMPC after surgery between 1998 and 2019 were identified from the Surveillance, Epidemiology, and End Results (SEER) database for survival analysis. Univariate and multivariate analyses were performed to explore independent prognostic factors for the overall and disease-specific survival of patients with IMPC. Five machine learning algorithms were developed to predict the 5-year survival of these patients.ResultsCox regression analysis indicated that patients aged > 65 years had a significantly worse prognosis than those younger in age, while unmarried patients had a better prognosis than married patients. Patients diagnosed between 2001 and 2005 had a significant risk reduction of mortality compared with other periods. The XGBoost model outperformed the other models with a precision of 0.818 and an area under the curve of 0.863.ConclusionsA machine learning model for IMPC in patients with breast cancer was developed to estimate the 5-year OS. The XGBoost model had a promising performance and can help clinicians determine the early prognosis of patients with IMPC; therefore, the model can improve clinical outcomes by influencing management strategies and patient health care decisions.

Elucidating the nature of acinic cell carcinoma of the breast with high-grade morphology: evidence from case report

BackgroundAcinic cell carcinoma (AciCC) of the breast is a rare subtype of breast cancer. It was considered a low-grade triple-negative breast cancer (TNBC) with the potential to progress or transform into a high-grade lesion because of the molecular similarities with conventional aggressive TNBC in several genetic studies. Microscopically, the coexistence of classical low-grade and high-grade triple-negative components in breast AciCC is not uncommon. However, there is a scarcity of research on the comparative histopathological and genetic aspects of both components.Case presentationA 34-year-old woman with a nontender mass in the upper outer quadrant of the left breast was initially diagnosed with a malignant small round cell tumor (undifferentiated or poorly differentiated carcinoma) based on a preoperative biopsy, which was later identified as breast AciCC with a high-grade solid component. Left breast-conserving surgery with sentinel lymph node biopsy was performed. Microscopically, the breast AciCC consisted of a classical acinic component and a high-grade component. The latter demonstrated a solid sheet-like pattern characterized by large, round, pleomorphic or vesicular nuclei, prominent nucleoli, and frequent mitotic activities. Classical acinic architectures focally merged together to form solid nests and transited into high-grade areas. Remarkably, in the high-grade lesion, conventional immunochemical markers for breast AciCC, such as α1-antitrypsin (AAT), Lysozyme (LYS), Epithelial membrane antigen (EMA), S100 protein (S100), and cytokeratin (CK) were negative, whereas cell cycle protein D1 (cyclin D1) and vimentin showed diffuse expression. Next‑generation sequencing (NGS) revealed that 43.5% of variants were identical in both components. Furthermore, PAK5 mutation; copy number (CN) loss of CDH1, CHEK1, and MLH1; and CN gains of CDK6, HGF, and FOXP1 were identified in the high-grade lesion. The patient was treated with eight cycles of adjuvant chemotherapy (epirubicin combined with cyclophosphamide) and radiotherapy after surgery, and she is currently alive for 43 months with no metastases or recurrences.ConclusionsThis case demonstrates a comparative analysis of the histopathological and genetic characteristics of classical low-grade and high-grade components of AciCC within the same breast. This information may serve as a morphological and molecular basis for further investigation into the molecular mechanisms underlying high-grade lesions in breast AciCC.

Spatial molecular profiling of mixed invasive ductal and lobular breast cancers reveals heterogeneity in intrinsic molecular subtypes, oncogenic signatures, and mutations

Mixed invasive ductal and lobular carcinoma (MDLC) is a rare histologic subtype of breast cancer displaying both E-cadherin positive ductal and E-cadherin negative lobular morphologies within the same tumor, posing challenges with regard to anticipated clinical management. It remains unclear whether these distinct morphologies also have distinct biology and risk of recurrence. Our spatially resolved transcriptomic, genomic, and single-cell profiling revealed clinically significant differences between ductal and lobular tumor regions including distinct intrinsic subtype heterogeneity - e.g., MDLC with triple-negative breast cancer (TNBC) or basal ductal and estrogen receptor positive (ER+) luminal lobular regions, distinct enrichment of cell cycle arrest/senescence and oncogenic (ER and MYC) signatures, genetic and epigenetic CDH1 inactivation in lobular but not ductal regions, and single-cell ductal and lobular subpopulations with unique oncogenic signatures further highlighting intraregional heterogeneity. Altogether, we demonstrated that the intratumoral morphological/histological heterogeneity within MDLC is underpinned by intrinsic subtype and oncogenic heterogeneity which may result in prognostic uncertainty and therapeutic dilemma.

Treatment patterns of adenoid cystic carcinoma of the breast: A systematic review.

e13147 Background: Adenoid cystic carcinoma of breast (ACC-B) is a rare subtype of breast cancer (BC) accounting for 0.1% of all BCs. It shares histologic features with ACCs arising in the salivary glands and other locations. Given the hormone receptor (HR) negative phenotype [negative expression of the estrogen receptor (ER), progesterone receptor (PR)], some clinicians treat ACC-B as a basal subtype of BC, which is predominantly treated with chemotherapy. However, ACC-B has a more indolent and favorable clinical behavior. There are no established treatment guidelines for ACC-B. We conducted a systematic review of the literature on the treatment patterns for ACC-B. Methods: We followed the PRISMA criteria using the database in Cochrane, Embase, PubMed, Scopus, and Web of Science. The Covidence software was used for screening and data extraction. Eligible studies discussed the management of stage I-III ACC-B from 1960 to 2022. Individual patient (pt) demographics, tumor characteristics, treatment and outcomes were collected, when available. Results: The database search found 2864 studies, of which 187 articles met the inclusion criteria in the study protocol. Given the rarity of this subtype of BC, most studies were case reports (n=104). A total of 4370 pts with a median age of 57 years were eligible for analysis. Information on ER, PR and HER2 status was not available for all cases. For the cases in which this was reported, most were ER and/or PR negative (76% ER negative and 83% PR negative). Surgery was the primary treatment reported for 3984 pts. A total of 21.5% underwent mastectomy, 40.7% lumpectomy and 37.7% were treated with other modalities of surgery. In the group of patients for which information was available regarding the receipt of systemic therapy (n=3147), 82% did not receive neoadjuvant or adjuvant chemotherapy. Metastatic disease was reported to have developed in 2.2% of the total patients (n=98). Median time to recurrence was 31 months (0-460) with a median overall survival of 134 months (1-462). The most common site of metastases were the lungs (60%). Among the patients who developed metastatic disease and for whom initial treatment information was available; radiation was given to 32 pts, 26 received adjuvant chemotherapy and 15 received both radiation and chemotherapy. No patients that developed metastatic disease received neoadjuvant chemotherapy. Conclusions: Our results suggests that ACC-B has a clinical behavior different from basal subtype of BC. In our review, only 2.2% of pts relapsed with metastatic disease, even though most of the pts did not receive prior systemic therapy. We need to better understand the genomic landscape of ACC-B, to identify pts who may be at risk for recurrence and develop specific guidelines to treat this rare type of BC.

Curative Approaches for Metaplastic Breast Cancer: A Retrospective Cohort Outcome Review

BackgroundMetaplastic breast cancer (MBC) is a rare and heterogeneous breast cancer subtype, and there are critical gaps in our understanding of its long-term outcomes. This retrospective cohort study aimed to address these gaps by scrutinizing the pathological and clinical aspects of MBC to enhance clinical decision-making and refine patient care strategies. MethodsThis registry-based retrospective cohort study included females aged ≥21 years diagnosed with MBC or matrix-producing carcinoma. The data were obtained from January 2001–August 2020 from the XXXX Registry of XXXX, which included 23,935 patients. Demographic and clinicopathological characteristics, neoadjuvant chemotherapy responses, and survival outcomes were analyzed. Statistical assessments involved univariate and multivariate Cox proportional hazards models and Kaplan–Meier survival analyses. ResultsThis study enrolled 170 patients; 87.1% had non-metastatic disease and 12.9% had metastatic disease. The age of patients at diagnosis ranged from 46 to 65 years (median, 56 years). The cohort's predominant characteristics were advanced clinical stage (77.6%), node negativity (67.6%), and grade 3 disease (74.1%). In patients receiving curative intent treatment, neoadjuvant chemotherapy yielded a pathological complete response of 19.2% and a disease progression rate of 46.2%. Multivariate analysis showed that adjuvant radiation therapy significantly improved overall survival (OS) and disease-free survival (DFS), with hazard ratios (HRs) of 0.29 (95% confidence interval [CI], 0.13 – 0.62; p < 0.005) and 0.23 (95% CI, 0.10–0.50; p < 0.005), respectively. Clinical T3 and T4 stages, and nodal involvement were associated with poor outcomes. Stable disease after neoadjuvant chemotherapy was associated with poor OS and DFS. Conclusion(s)This study sheds light on the complex landscape of MBC and emphasizes the pivotal role of adjuvant radiotherapy in enhancing patient outcomes. Despite advancements, challenges persist that warrant continued research to refine neoadjuvant chemotherapy strategies and delve into the nuanced factors that influence treatment responses.

Neuroendocrine Breast Carcinoma: Interesting Images of an Underdiagnosed Entity.

Breast cancer is the most common type of cancer of the female gender. A rare subtype of breast cancer is the invasive breast carcinoma (IBC) with neuroendocrine (NE) differentiation. Its incident is believed to be 0.1% to 5% of all breast cancers. We report a rare case of a 66-year old woman who presented with an isolated nodule of the left breast. The patient underwent modified radical mastectomy. Pathology revealed invasive breast carcinoma with neuroendocrine differentiation. Invasive breast carcinoma is an extremely rare group of neoplasms, the exact frequency of which cannot be determined with current data. Therefore, it is necessary for future studies to focus on the pathophysiology of this subtype of breast cancer and on the potential therapeutic approaches.

Breast conservation versus mastectomy for metaplastic breast cancer: A systematic review and meta-analysis.

Metaplastic breast cancer is a rare aggressive subtype of breast cancer for which there are no clear treatment guidelines regarding the optimal surgical approach. This systematic review and meta-analysis aimed to evaluate survival outcomes of patients with metaplastic breast cancer undergoing breast conservation compared with mastectomy. We identified studies from MEDLINE, Pubmed, EMBASE, Google Scholar, the Cochrane Library Register of Controlled Trials and the EBM Reviews Register. Studies were deemed suitable for inclusion where they compared breast-conserving surgery to mastectomy with the primary outcome of overall survival. Survival data were pooled using a random-effects model. From the 456 citations screened by our search, three studies were assessed as eligible for inclusion. There were a total of 2995 patients who underwent mastectomy and 1909 who underwent breast conservation. The median follow-up time was 43 months. Meta-analysis demonstrated no significant difference between breast conservation and mastectomy (pooled HR 0.89, 95% CI, 0.56-1.42, p=0.631). Wide local excision, in conjunction with adjuvant radiation and judicious use of chemotherapy, may be a reasonable alternative to mastectomy as surgical management of metaplastic breast cancer as part of an individualized, multidisciplinary approach.

Abstract PO5-17-07: MUCINOUS BREAST CARCINOMA: REAL WORLD DATA IN A REFERENCE CENTER IN SÃO PAULO

Abstract BACKGROUND: Mucinous breast carcinoma (MC) is a subtype of invasive carcinoma that corresponds to 1 to 6% of all types of breast cancer. It occurs when the mucinous component accounts for more than 50% of the tumor producing extracellular mucin in large scale. Mucin is a complex carbohydrate engaged in processes such as epithelial differentiation, adhesion modulation and cell signaling. Along with other special types of breast neoplasia, MC appears to have an unique behavior and, since it’s low amount of cases, a detailed clinical evaluation has been difficult. OBJECTIVES: To describe the profile of patients with breast MC that were treated in a reference center in São Paulo, Brazil as well as evaluate its management and outcomes. METHODS: A descriptive longitudinal observation study conducted at São Paulo’s Women’s Health Reference Center - Hospital da Mulher from July 2022 to January 2023, based on 192 medical records of patients diagnosed with MC from 2003 to 2018. RESULTS: 192 patient’s records were included. The age range was 31-93 years, out of which 74,3% of the patients were older than 50 when diagnosed. 48,7% identified as white and 43,7% showed earlier diagnoses of systemic hypertension. The time range between diagnosis and first treatment was 4,5 months. Out of the histopathological features, the nuclear grade was 3 in 69 patients (34,6% of the cases), and histological grade 1 in 52,7%. About pathological staging, the size of the tumors went form 0,5 to 9,5 cm, with an average of ± 4,7cm, the majority of them showed positive ER (89,4%), negative PR (85%), and were negative for Her-2 (76%). Greater number of patients (92,4%) went through both clinical and surgical treatment. Only 15 (7,5%) had isolated clinical treatment. 31% of the patients received systemic chemotherapy treatment, 25% of those were neoadjuvant. 81,9% of patients received aromatase inhibitor and only 17% radiotherapy. Distant metastasis were diagnosed in 27 patients (13,5%) and the local recurrence was observed in 15,3%. Out of distant metastasis, pulmonary type was more prevalent, registered in 45,7% of patients, followed by osseous (22,88%) and hepatic (14,2%). 33 patients (16,5%) progressed to death, however, the specific cause was not determined. CONCLUSION: MC is a rare subtype of breast cancer, more prevalent in post-menopausal and white women. Frequently shows low histological grade and positive hormonal receptors, which reinforces the idea of a indolent behavior. The treatment is mostly surgical, with adjuvance if necessary. Metastasis are infrequent and knowing the profile of patients with MC, as well as it’s behavior, allows the better management when facing this diagnosis. Citation Format: Marina Fleury De Figueiredo, Andre Mattar, Felipe Cavagna, Ana Lígia Minatel da Silva, Rafaella Nadai, Juliana Medeiros de Oliveira, Luma Fleury de Figueiredo. MUCINOUS BREAST CARCINOMA: REAL WORLD DATA IN A REFERENCE CENTER IN SÃO PAULO [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-17-07.

Abstract PO3-20-11: Among the &amp;lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma

Abstract Among the &amp;lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma Sera Choi, B.A., Sarah Keshwani, M.D., Andrea Madrigrano, M.D. Introduction: Adenoid cystic carcinoma in the breast (ACCB) is a rare subtype of breast cancer that accounts for &amp;lt; 0.1% of all breast-related malignancies. The majority of ACCB cases in existing literature are comprised of estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor 2 negative, abbreviated as triple-negative breast cancer. Although most triple negative breast cancers are aggressive in nature and prognosis, ACCB is reported to be more indolent with a favorable outcome. This disparity raises the question of whether the treatment approach for ACCB should follow the well-established treatment plan for other triple negative breast cancers given its atypical characteristics. Furthermore, while adenoid cystic carcinoma of the salivary glands is a well-known type of head and neck cancer with established treatment guidelines, there is limited data for recommendations regarding treatment for ACCB. We report a pathologically confirmed case of ACCB and review the existing literature regarding treatment strategy and prognosis. Case: This case is of a 69-year-old female who presented with an abnormal screening mammogram with a core needle biopsy confirming ACCB in the left lower outer quadrant. The patient was asymptomatic with no palpable masses, nipple discharge, or skin changes of the breast. Biopsy revealed adenoid cystic carcinoma grade 2, classic type, with immunochemistry confirming estrogen-receptor negative, progesterone-receptor negative, and human epidermal growth factor-receptor negative. After a thorough discussion of the options, the patient elected for breast conserving therapy and sentinel lymph node biopsy. Tumor was resected with negative margins and two out of two lymph nodes were negative for metastasis. The patient was recommended whole breast adjuvant radiation therapy given the large tumor size of 4.8cm. Chemotherapy was not recommended due to data that largely supports local targeted therapy over systemic treatment in patients without metastatic ACCB. The patient is continuing with routine follow-up evaluations. Discussion: Currently, mainstay treatment comprises of surgical resection with lumpectomy or mastectomy, with or without nodal evaluation. Radiation therapy is seen as beneficial in reducing recurrence and prolonging disease-free survival in ACCB. There is ongoing debate regarding the role of chemotherapy in ACCB patients, as triple-negative breast cancers are typically treated with a systemic chemotherapy regimen. However, since ACCB has a more favorable prognosis, the role of chemotherapy remains uncertain. With lack of data on ACCB, treatment modalities should be evaluated on a case-by-case basis. Moreover, considering the scarcity of information concerning this particular subtype of breast cancer, it is advisable to discuss these patients within a multi-disciplinary tumor board setting to ensure patients receive the maximum benefit. Citation Format: Sera Choi, Sarah Keshwani, Andrea Madrigrano. Among the &amp;lt; 0.1 percent of breast cancers: A case of adenoid cystic carcinoma [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-20-11.

Abstract PO3-14-08: Metaplastic Breast Cancer: Whole Genome Sequencing Analysis and Emerging Therapeutic Targets

Abstract Background: Metaplastic breast cancer (MpBC) is a rare histologic subtype of triple negative breast cancer (TNBC) with an aggressive behavior and poor outcome. Previous studies by whole-exome and targeted sequencing showed that MpBCs display a dominant mutational signature 3, associated to homologous recombination (HR) deficiency (HRD). Tumors displaying HRD are associated with response to therapies causing double strand breaks. Nonetheless, MpBCs consistently display significantly lower rates of response to neoadjuvant chemotherapy than non-metaplastic TNBCs and effective therapeutic alternatives are an unmet clinical need. Here we sought to assess the HR features of MpBCs using whole-genome sequencing (WGS), and to evaluate the expression in MpBCs of antigens that are targets of novel antibody drug conjugates (ADCs) in common forms of breast cancer. In addition, we sought to assess the efficacy of ADCs and drugs targeting the DNA damage response (DDR) using preclinical MpBC models. Materials and Methods: We subjected 25 primary MpBC to WGS. HRDetect, the ‘gold standard’ tool for assessment of HRD, was utilized. Mutational signatures were inferred using Signal. 31 MpBCs were subjected to RNA-sequencing to assess the gene expression levels ADC targets compared to non-MpBCs from The Cancer Genome Atlas (TCGA). Efficiency of ADCs and DDR drugs was evaluated using the MpBC cell models HCC1806, BT549 and Hs578T in vitroand/or using HCC1806 xenografts in athymic mice in vivo. Results: Although the majority of MpBCs (13/25) displayed a dominant SBS mutational signature 3, only a small subset of cases (3/25) were classified as HRD by HRDetect. These three bona fide HRD cases were found to harbor bi-allelic inactivation of BRCA1 (n=2) or RAD51C (n=1), and displayed various genomic features of HRD, including deletions with microhomology, enrichment in tandem duplications, rearrangement signatures 3 and 5, and high large scale state transitions (LST) and telomeric allelic imbalance (NtAI) scores. Most MpBCs (22/25), however, were not classified as HRD by HRDetect displaying an incomplete HRD phenotype, with only partial genomic features of HRD. 52% of MpBCs (13/25) displayed APOBEC mutagenesis exposure, which was present in the three bona fide HRD MpBCs. RNA-sequencing analyses revealed detectable ERBB2 and TROP2 expression in all MpBCs interrogated, although at lower levels than in non-MpBCs from TCGA. The HCC1806, BT549 and Hs578T MpBC cell models were found to be sensitive to Sacituzumab Govitecan and Trastuzumab Deruxtecan (T-DXd) in cell viability and colony formation assays, and to T-DXd in vivo. These MpBC cell models were also found to be sensitive to DDR compounds, such as ATR, WEE1 and PKMYT1 inhibitors in vitro, alone and in combination with T-DXd or Sacituzumab Govitecan. Conclusions: Most MpBCs display an incomplete HRD genomic scar, except for those cases harboring bi-allelic inactivation of HRD genes. APOBEC mutagenesis is operative in MpBCs and co-exists with HRD. MpBCs express ERBB2 and TROP2, and MpBC cell models are sensitive to T-DXd and Sacituzumab govitecan, as well as DDR compounds, targeting the incomplete HRD phenotype of MpBCs, alone and in combination. Taken together, these findings warrant further studies in patients with MpBCs testing the therapeutic efficacy of agents targeting the incomplete HRD phenotype, as well as the expression of ADC targets in these aggressive rare forms of TNBCs. Citation Format: Fresia Pareja, Andrea Gazzo, Higinio Dopeso, David Brown, Pier Selenica, Yingjie Zhu, Juan Blanco-Heredia, Laxmi Gusain, Xin Pei, Giacomo Montagna, Nour Abuhadra, Hanna Y Wen, Edi Brogi, Nadeem Riaz, Sarat Chandarlapaty, Maurizio Scaltriti, Larry Norton, Simon Powell, Jorge Reis-Filho, Britta Weigelt. Metaplastic Breast Cancer: Whole Genome Sequencing Analysis and Emerging Therapeutic Targets [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-14-08.

Abstract PS16-08: Histologic Pattern and Outcomes in High-Grade Metaplastic Breast Cancer Compared to Triple-Negative Ductal Breast Cancer Counterparts: A Single Institution Retrospective Study

Abstract Background Metaplastic breast cancer (MpBC) is a rare and aggressive subtype of breast cancer that presents with high tumor stage and a poor prognosis. MpBC tumors tend to have worse outcomes compared to other non-metaplastic triple-negative breast cancers (TNBC). Although MpBC has been described as chemotherapy resistant, chemotherapy remains a mainstay of treatment. MpBC tumors can be further characterized by their specific histologic pattern. The existing literature on outcomes of MpBC by histologic pattern is limited, with varying results regarding response rate and overall survival (OS). Identifying a pattern of MpBC that has better response to treatment could help tailor treatment recommendations. Methods A retrospective chart review was performed and identified 106 patients with early-stage, high-grade MpBC who were diagnosed at Levine Cancer Institute between January 1, 2010 and September 1, 2021. A matched control cohort (n=106) of patients diagnosed with non-metaplastic TNBC was selected based on propensity score matching on diagnosis date, age at diagnosis, race, pathologic staging, and tumor grade. Patient demographics, tumor characteristics, therapeutic interventions, residual cancer burden (RCB), and outcomes were collected. The associations between the histologic patterns of MpBC and disease characteristics were evaluated using chi-squared tests for categorical variables and Wilcoxon tests for continuous variables. We also examined the differences in RCB scores between the MpBC cohort and the non-metaplastic TNBC cohort who received neoadjuvant chemotherapy. Additionally, Kaplan-Meier and Cox proportional hazard analysis was performed to assess differences in recurrence free survival (RFS) and OS between the spindle cell/sarcomatous pattern versus all other patterns. Results For the entire group (n=212), median age at diagnosis was 58 years (range, 24-92); all patients were female; 66% White, 29% Black, and 5% unknown race. Most tumors were triple-negative (91%); 19%, 56% and 14% with Clinical Stage I, II, and III disease, respectively. A total of 63% of patients underwent radiation treatment and 76% received chemotherapy (43% neoadjuvant and 57% adjuvant). Recurrence after treatment occurred in 16% of all patients. In the MpBC cohort (n=106), the histologic patterns included spindle cell/sarcomatous (34%), squamous (17%), heterologous mesenchymal (31%), mixed (17%), and other (1%). Of those with MpBC who received neoadjuvant chemotherapy (n=32), RCB among the different histologic patterns was assessed. When comparing spindle cell/sarcomatous versus the other histologic patterns combined, there was no significant difference in RCB (p = 0.81), although more RCB III scores were recorded in the spindle cell/sarcomatous pattern compared to the other MpBC patterns (40% versus 30%). When assessing RFS and OS by histologic pattern in the entire MpBC cohort, spindle cell/sarcomatous tumors had inferior RFS (p = 0.0194) and OS (p = 0.0039) compared to the other MpBC patterns combined. When comparing RCB values between MpBC and non-metaplastic TNBC, there were numerically more RCB-III classes in the MpBC cohort as compared to the non-metaplastic TNBC. Conclusion MpBC is an aggressive and difficult breast malignancy to treat. Based on our single institution review, no correlation between RCB and the histologic pattern of MpBC was found, however, RFS and OS were worse among the spindle cell/sarcomatous pattern. Furthermore, the MpBC cohort had numerically higher RCB-III scores than the TNBC control cohort, which is in line with historical data. Citation Format: Ashley Matusz-Fisher, Annabel Chen, Erin Donahue, Courtney Schepel, Michelle Wallander, Chad Livasy, Richard White, Antoinette Tan, Lejla Hadzikadic-Gusic. Histologic Pattern and Outcomes in High-Grade Metaplastic Breast Cancer Compared to Triple-Negative Ductal Breast Cancer Counterparts: A Single Institution Retrospective Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS16-08.

Cytomorphological features of sebaceous carcinoma of the breast.

Sebaceous carcinoma of the breast is an extremely rare histological subtype of breast cancer, with fewer than 30 cases reported to date. Because of its extremely rare histological presentation, there are few case reports that highlight its cytological findings. In this case report, the cytomorphological features of a sebaceous carcinoma of the breast are described in detail. Cytomorphological analysis revealed atypical cells presenting predominantly as loose clusters. No tubular or papillary structures were evident in the clusters and no mucin production was observed. The diagnosis of sebaceous carcinoma of the breast requires prominent sebaceous differentiation of cells. In Papanicolaou-stained smears, the differentiated tumor cells were found within the yellowish clusters. When these yellowish clusters were observed at high magnification and shifted out of focus, the sebaceous differentiation of tumor cells could be recognized. This finding is an advantage of observing Papanicolaou-stained specimens. Like previous reports, some individual cells showing sebaceous differentiation were also observed. In cases where many yellowish clusters appear, close observation of the interior of the clusters can confirm the presence of sebaceous differentiation of tumor cells and serve as a diagnostic clue for the cytological diagnosis of sebaceous carcinoma of the breast.

Establishment of Prognostic Nomogram for Male Breast Cancer Patients: A Surveillance, Epidemiology and End Results Database Analysis.

Male breast cancer (MBC) represents a rare subtype of breast cancer, with limited prognostic factor studies available. The purpose of this research was to develop a unique nomogram for predicting MBC patient overall survival (OS) and breast cancer-specific survival (BCSS). From 2010 to 2020, clinical characteristics of male breast cancer patients were obtained from the Surveillance, Epidemiology and End Results (SEER) database. Following univariate and multivariate analyses, nomograms for OS and BCSS were created. Kaplan-Meier plots were further generated to illustrate the relationship between independent risk variables and survival. The nomogram's ability to discriminate was measured by employing the area under a time-dependent receiver operating characteristic curve (AUC) and calibration curves. Additionally, when the nomogram was used to direct clinical practice, we also used decision curve analysis (DCA) to evaluate the clinical usefulness and net clinical benefits. A total of 2143 patients were included in this research. Univariate and multivariate analysis showed that age, grade, surgery, chemotherapy status, brain metastasis status, subtype, marital status, race, and AJCC-T, AJCC-N, and AJCC-M stages were significantly correlated with OS. Lung metastasis, age, marital status, grade, surgery, and AJCC-T, AJCC-N, and AJCC-M stages were significantly correlated with BCSS. By comprising these variables, a predictive nomogram was constructed in the SEER cohort. Then, it could be validated well in the validation cohort by receiver operating characteristics (ROCs) curve and calibration plot. Furthermore, the nomogram demonstrated better decision curve analysis (DCA) results, indicating the ability to forecast survival probability with greater accuracy. We created and validated a unique nomogram that can assist clinicians in identifying MBC patients at high risk and forecasting their OS/BCSS.

A prognostic nomogram based on least absolute shrinkage and selection operator Cox regression in patients with pulmonary large-cell neuroendocrine carcinoma.

Pulmonary large-cell neuroendocrine carcinoma (LCNEC) is a rare subtype of breast cancer with a poor prognosis. Despite its rarity, it is important to gain a better understanding of the epidemiological, clinical, and prognostic features of pulmonary LCNEC. The purpose of this study was to design, construct, and validate a new nomogram for predicting overall survival (OS) in patients with pulmonary LCNEC. In total, the data of 1,864 LCNEC patients were extracted from the Surveillance, Epidemiology, and End Results (SEER) database, which is maintained by the National Cancer Institute in the United States and serves as a comprehensive source of cancer-related information. Of these patients, 556 served as the validation group and 1,308 served as the training cohort. We constructed a new nomogram with the training cohort that included the independent factors for OS as identified by least absolute shrinkage and selection operator Cox regression. Five independent factors were ultimately selected by the stepwise regression. Every factor of the Cox regression was included in the nomogram. Analyses of the calibration curve, decision curve, area under the curve, and concordance index (C-index) values were performed to assess the effectiveness and discriminative ability of the nomogram. Five optimal predictive factors for OS were selected and merged to construct a 3- and 5-year OS nomogram. The nomogram had C-index values of 0.716 and 0.708 in the training cohort and validation cohort, respectively. The actual OS rates and the calibration curves showing the predictions of the nomogram were in good agreement. The prognostic nomogram may be very helpful in estimating the OS of patients with pulmonary LCNEC.

Identification of barriers at the primary care provider level to improve inflammatory breast cancer diagnosis and management

The purpose of this study, based in the United States, was to evaluate knowledge gaps and barriers related to diagnosis and care of inflammatory breast cancer (IBC), a rare but lethal breast cancer subtype, amongst Primary Care Providers (PCP) as they are often the first point of contact when patients notice initial symptoms. PCP participants in the Duke University Health System, federally qualified health center, corporate employee health and community practices, nearby academic medical center, Duke physician assistant and advanced practice nurse leadership program alumni were first selected in a convenience sample and for semi-structured interviews (n = 11). Based on these data, an online survey tool was developed and disseminated (n = 78) to assess salient measures of IBC diagnosis, health disparity factors, referral and care coordination practices, COVID-19 impact, and continuing medical education (CME). PCP reported access to care and knowledge gaps in symptom recognition (mean = 3.3, range 1–7) as major barriers. Only 31 % reported ever suspecting IBC in a patient. PCP (n = 49) responded being challenged with referral delays in diagnostic imaging. Additionally, since the COVID-19 pandemic started, 63 % reported breast cancer referral delays, and 33 % reported diagnosing less breast cancer. PCP stated interest in CME in their practice for improved diagnosis and patient care, which included online (53 %), lunch time or other in-service training (33 %), patient and provider-facing websites (32 %). Challenges communicating rare cancer information, gaps in confidence in diagnosing IBC, and timely follow-up with patients and specialists underscores the need for developing PCP educational modules to improve guideline-concordant care.

Secretory breast carcinoma: clinicopathological features and prognosis of 52 patients.

Secretory breast carcinoma is a rare histological subtype of invasive breast cancer and considered with an indolent clinical behavior. This study was conducted to analyze the clinicopathological features of patients with secretory breast carcinoma (SBC), explore the outcome, and compare the prognostic difference with invasive ductal breast carcinoma (IDC). METHODSAND MATERIALS: Patients with SBC diagnosed between 2006 and 2017 from Fudan University Shanghai Cancer Center were included in the study, excluding patients with previous malignant tumor history and incomplete clinical data or follow-up records. Peculiar clinicopathological and immunohistochemical features of the cases were fully described. Clinical data of 4979 cases of IDC were also evaluated during this period. After propensity score matching, prognostic analysis of SBCs and IDCs was calculated by Kaplan-Meier method and landmark analysis method. The data of 52 patients diagnosed with SBC were identified from the pathological files. Among them, 47 patients were women, and 5 were men. The median age of the 52 SBCs was 46years (mean, 48.1years; range, 10-80years). The tumor sizes ranged from 0.3 to 6.8cm, with a mean of 3.5cm. Eight patients (15.4%) had positive axillary lymph node involvement. The molecular classification was mostly triple-negative breast cancer (65.4%). Fluorescence in situ hybridization confirmed the presence of ETV6::NTRK3 rearrangement in 16 of 18 cases (88.9%). Furthermore, Kaplan-Meier survival analysis and landmark analysis demonstrated that there were no statistically significant differences in DFS and OS between SBC and IDC patients. Although SBCs are generally associated with a favorable prognosis, our work exhibited that the clinicopathological features of SBC were partly different from former understandings, indicating that therapeutic procedure should be prudent. Further studies are necessary to fully identify the clinical behavior and predictive markers to improvediagnosis and management in this unique subtype of breast cancer.

Construction and validation of a nomogram for predicting the prognosis of patients with lymph node-positive invasive micropapillary carcinoma of the breast: based on SEER database and external validation cohort

BackgroundInvasive micropapillary carcinoma (IMPC) of the breast is a rare subtype of breast cancer with high incidence of aggressive clinical behavior, lymph node metastasis (LNM) and poor prognosis. In the present study, using the Surveillance, Epidemiology, and End Results (SEER) database, we analyzed the clinicopathological characteristics and prognostic factors of IMPC with LNM, and constructed a prognostic nomogram.MethodsWe retrospectively analyzed data for 487 breast IMPC patients with LNM in the SEER database from January 2010 to December 2015, and randomly divided these patients into a training cohort (70%) and an internal validation cohort (30%) for the construction and internal validation of the nomogram, respectively. In addition, 248 patients diagnosed with IMPC and LNM at the Fourth Hospital of Hebei Medical University from January 2010 to December 2019 were collected as an external validation cohort. Lasso regression, along with Cox regression, was used to screen risk factors. Further more, the discrimination, calibration, and clinical utility of the nomogram were assessed based on the consistency index (C-index), time-dependent receiver operating characteristic (ROC), calibration curve, and decision curve analysis (DCA).ResultsIn summary, we identified six variables including molecular subtype of breast cancer, first malignant primary indicator, tumor grade, AJCC stage, radiotherapy and chemotherapy were independent prognostic factors in predicting the prognosis of IMPC patients with LNM (P &amp;lt; 0.05). Based on these factors, a nomogram was constructed for predicting 3- and 5-year overall survival (OS) of patients. The nomogram achieved a C-index of 0.789 (95%CI: 0.759-0.819) in the training cohort, 0.775 (95%CI: 0.731-0.819) in the internal validation cohort, and 0.788 (95%CI: 0.756-0.820) in the external validation cohort. According to the calculated patient risk score, the patients were divided into a high-risk group and a low-risk group, which showed a significant difference in the survival prognosis of the two groups (P&amp;lt;0.0001). The time-dependent ROC curves, calibration curves and DCA curves proved the superiority of the nomogram.ConclusionsWe have successfully constructed a nomogram that could predict 3- and 5-year OS of IMPC patients with LNM and may assist clinicians in decision-making and personalized treatment planning.