Risk Of Ipsilateral Breast Tumor Recurrence Research Articles

Abstract PO4-22-02: pSmad2 as a marker of radiotherapy benefit in breast cancer- results from the randomized SweBCG91RT trial

Abstract Background: The TGF-beta pathway can have both pro- and antitumoral effects in breast cancer. Experimental studies further suggest that TGF-beta can mediate radioresistance, either through direct effects on tumor cells or indirectly by its immunomodulatory properties. However, the effect of TGF-beta signaling is highly depending on tumor stage, mutational status and microenvironmental cell composition. In order to explore TGF-beta signaling as a potential biomarker or therapeutical target it is therefore important to perform analyses in well-defined study populations. The purpose of this study was to study the effect of active TGF beta signaling in tumor cells, on the risk of ipsilateral breast tumor recurrence (IBTR) and benefit from radiotherapy (RT) in specifically early-stage breast cancer using nuclear, phosphorylated Smad2 (pSmad2) as a marker. Methods: The SweBCG91RT cohort included 1179 patients with stage I-IIA tumors randomized to breast-conserving surgery (BCS) with or without postoperative RT. Nuclear pSmad2 expression was assessed as for 987 available tumors on TMAs as the mean proportion of tumor cells with positive nuclear staining. Based on the distributions, tumors were categorized as having high (≥80%, n=344), medium (21-79%, n=428) or low (≤20%, n=161) pSmad2 staining. The primary endpoint was time to ipsilateral breast tumor recurrence as the first event within 10 years. Results: pSmad2Low tumors were more likely to be of grade III (p< 0.001) and tended to be larger than pSmad2Medium (p=0.002, median 15 vs 12 mm) and pSmad2High (p< 0.001, median 15 vs 12 mm) tumors. No associations between pSmad2 and subtype or age were found. Numerically, tumors with pSmad2low (HR 1.55, CI 95% 0.80-3.02, p=0.19) or pSmad2Medium (HR 2.53, CI 95% 1.52-4.22, p< 0.001) had a higher risk of IBTR than pSmad2high tumors (reference). These findings remained significant after adjustment for age, histological grade, and RT. The benefit from RT was similar for pSmad2High (HR0.41, CI 95% 0.15-1.07, p=0.068), pSmad2Medium (HR 0.36, CI 95% 0.21-0.63, p< 0.001), and pSmad2Low (HR 0.51, CI 95% 0.18-1.46, p=0.21) tumors (pinteraction=0.86). Conclusions: Early-stage breast tumors with high nuclear pSmad2 staining may be at a reduced risk of an IBTR. However, the relative benefit from RT does not seem to differ from tumors with medium or low pSmad2 staining. These results need to be confirmed in additional studies, but they provide initial evidence that tumoral TGF-beta signaling has rather tumor restraining functions in early-stage breast cancer. Next analytical steps should include the tumor mutation status (particularly for TGF-beta signaling components TGFBR2, SMAD4 and TP53), as well as the TGF-beta signaling status within the tumor microenvironment. Citation Format: Per Karlsson, Viktoria Thurfjell, Anikó Kovács, Fredrika Killander, Emma Niméus, Erik Holmberg, Carina Strell, Axel Stenmark Tullberg. pSmad2 as a marker of radiotherapy benefit in breast cancer- results from the randomized SweBCG91RT trial [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 PO4-22-02.

Abstract PO5-22-04: Genomic analysis of local recurrences following risk adapted breast radiotherapy in the IMPORT trials defines 'true recurrences' and 'new primaries'

Abstract Background: Most ipsilateral breast tumor recurrences (IBTR) following breast conserving surgery occur near the tumor bed (Veronisi et al, Ann Oncol 2001) and are considered to represent ‘true recurrence’ (derived from residual malignant cells of the index cancer). A smaller number occur elsewhere in the breast and are thought to be ‘new primaries’ (independently occurring cancer). The IMPORT LOW (Coles et al, The Lancet 2017) and IMPORT HIGH (Coles et al, The Lancet 2023) trials investigated adaptation of radiotherapy dose-volume to this spatially varying risk, testing partial breast irradiation and simultaneous integrated boost in patients with tumors at low and high risk of IBTR respectively. We analysed genomic relationships between index cancers and recurrences in these trials, to ascertain the frequency of true recurrences and unrelated new primaries, and their spatial distribution. Methodology: FFPE blocks were obtained from 137 patients who developed subsequent ipsi- or contralateral breast cancer: 66 from IMPORT HIGH and 71 from IMPORT LOW (4 with bilateral second cancers). DNA extracted from index and subsequent cancers underwent shallow whole genome sequencing (sWGS) using the Illumina NovaSeq 6000 system. Copy number profiles were derived from sWGS data using the R package QDNAseq(Scheinin et al, Genome Res 2014); those that failed QC criteria were removed. Relatedness of tumor pairs was determined using the R package Breakclone (Lips et al, Nat Genet 2022). This approach uses individual copy number aberration breakpoint position rather than events at chromosomal arm level. The p value cutoff for relatedness was 0.01; values between 0.01 and 0.05 were considered ambiguous. Researchers were blinded to clinical information prior to results. Results: In 80/137 tumor pairs both copy number profiles met QC criteria and clonal relationship could be ascertained. In total 26/80 were considered related, 20/80 ambiguous and 34/40 non-related (Table 1). 16/26 ipsilateral subsequent cancers in IMPORT HIGH were clonally related to the primary tumor and could be considered true recurrences. In 5/26 it was impossible to accurately call clonality as pairs shared only common copy number changes such as 1q or 8q gain and 16q loss. 5/26 were considered new primaries. In the lower risk IMPORT LOW cohort, subsequent cancers appear to have similar chances of being related or independent. As expected, most contralateral tumors in IMPORT LOW showed no evidence of a clonal relationship to the index tumors. In both trials an ambiguous subgroup of pairs shared some common copy number changes suggesting similar phenotype.5/14 contralateral tumors in IMPORT HIGH, in which some women were also at high risk of systemic relapse, shared very similar copy number profiles to the index tumor and may be metastases rather than new primaries. Discussion: A considerable number of tumors classed as IBTR appear genomically unrelated to the index cancer particularly in low risk cancer; this biology is relevant to clinical management both initially and at ‘recurrence’. The finding that 5/14 contralateral cancers in the high risk group appear to be clonally related suggests that some may be metastases. Results are being confirmed by targeted sequencing and will be correlated with recorded spatial and clinicopathological data and patient outcome. Future work will analyse spatial relationships more precisely using deformable image registration. *From the 77 patients with baseline circulating tumor DNA samples, 2 patients were excluded because their samples failed during assay quality control. Table. PIK3CA and ESR1 alterations detected in circulating tumor DNA at baseline and post abemaciclib treatment Citation Format: Sara Lightowlers, Maria Roman-Escorza, Elena Provenzano, Judith Bliss, Jason Carroll, H Y Charlie Chan, Clare Griffin, Joanne Haviland, Monica Jefford, Anna Kirby, Navita Somaiah, Mark Sydenham, Jenny Titley, John Yarnold, Charlotte Coles, Elinor Sawyer. Genomic analysis of local recurrences following risk adapted breast radiotherapy in the IMPORT trials defines 'true recurrences' and 'new primaries' [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 PO5-22-04.

Comparison of long-term oncologic outcomes of central lumpectomy and conventional breast-conserving surgery for invasive breast cancer: propensity score matching analysis.

Central lumpectomy (CL) is a breast-conserving surgical (BCS) technique that involves excision of the nipple-areolar complex with breast tumor in centrally located breast cancers. We aimed to investigate the long-term clinical outcomes of CL in comparison with conventional BCS (cBCS). Patient records who underwent BCS with clear resection margins for invasive breast cancer between 2004 and 2018 were retrospectively reviewed. Of the total 6,533 patients, 106 (1.6%) underwent CL. Median follow-up duration was 73.4months. 1:3 propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were used to minimize selection bias. The CL group showed a significantly higher ipsilateral breast tumor recurrence (IBTR) rate than the cBCS group (10-year IBTR rate: 5.8% vs. 3.1%, p = 0.004), even after adjusting for other variables (hazard ratio (HR), 2.65; 95% confidence interval (CI), 1.07-6.60, p = 0.048). However, there were no significant differences observed inregional recurrence, distant metastasis, oroverall survival rates between the two groups. Both PSM and IPTW analyses showed significantly higher IBTR in the CL group (PSM HR, 3.27; 95% CI, 0.94-11.36; p = 0.048 and IPTW HR, 4.66; 95%CI, 1.85-11.77; p < 0.001). Lastly, when analyzing 2,213 patients whose tumors were located within 3cm of the nipple, the CL group showed a significantly higher IBTR than the cBCS group before and after PSM. CL was associated with a higher rate ofIBTR compared to cBCS, while other survival outcomes were comparable. For centrally located tumors, CL may be considered for patients preferring breast preservation. However, higher risk for IBTR should be informed and careful surveillance may be necessary during the early post-operative follow-up periods.

Oncological outcomes of post neo adjuvant chemotherapy breast conservation surgery in patients with locally advanced breast cancer

Abstract Introduction: Breast cancer in India is phenotypically different with locally advanced breast cancers (LABCs) forming 30–50% of all cases. Use of neoadjuvant chemotherapy (NACT), among other things has contributed to surgeons using breast conservation surgery (BCS) in very selected patients with good results. Herein, we describe the oncological outcomes of BCS in LABC patients undergoing surgery post NACT. Patients and Methods: This is an ambispective observational cohort study conducted between January 1996 and December 2019 after approval by Institute Ethics Committee, to study the ipsilateral breast tumor recurrence (IBTR) in patients with LABC undergoing BCS post NACT. The secondary objectives were to ascertain the disease-free survival (DFS) and overall survival (OS) and factors associated with IBTR in these patients. Patients were staged according to the anatomic American Joint Committee on Cancer (AJCC) VIII Tumor Node Metastasis (TNM) classification and clinic-demographic, pathologic, treatment, and follow-up details were noted. Results: Out of 822 patients with LABC, 71 patients undergoing BCS post NACT were included. Average tumor size at presentation was 6.43 cm. The most common T stage was T3 (57.7%) and N stage was N1 (53.5%). The most common stage group was IIIB in 40.8%. Around 75% received anthracycline-based NACT with 28.2% having a complete clinical response. A pathological complete response was seen in 16 patients (22.5%). The mean follow-up duration was 6.14 years. A total of 25 patients had recurrences: five patients had IBTR (7%) and four had a local with regional recurrence. Two, 5, and 10 years OS were 94.0, 83.8, and 61.9%, respectively, and DFS were 87.8, 67.1, and 50.6%, respectively. A higher clinical T stage was associated with poor DFS (p = 0.01). The risk of IBTR was not found to significantly correlate with any of the standard prognostic factors. Conclusion: BCS post NACT in suitably selected patients of LABC is a safe and viable option without adversely affecting oncological outcomes.

Comparison of long-term oncological outcomes after central lumpectomy versus nipple-sparing breast-conserving surgery for centrally located breast cancer: a propensity score-matched study.

To compare the oncological safety of nipple-sparing breast-conserving surgery (BCS) versus central lumpectomy for centrally located breast cancer (CLBC). Patients who underwent BCS for CLBC at Asan Medical Center from 2007 to 2018 were reviewed retrospectively. The oncological outcomes of nipple-sparing BCS (NS-BCS) and central lumpectomy were compared using univariate and multivariate Cox regression analyses and compared again after 1:1 propensity score matching (PSM). The study included 306 patients who underwent NS-BCS and 106 patients who underwent central lumpectomy (median follow-up: 111months). On multivariate analysis, central lumpectomy had a lower risk of local recurrence compared to NS-BCS, albeit without statistical significance (HR 0.14, 95% CI 0.02-1.24; p = 0.077). There was no significant difference in the risk of death (HR 0.14, 95% CI 0.01-1.68, p = 0.12). After PSM, each group had 106 patients. The 5-year and 10-year local recurrence-free survival rates were 94.2% and 92.9% for NS-BCS, and 99.1% and 99.1% for central lumpectomy, respectively (p = 0.031). There were no significant differences in overall survival, regional recurrence-free survival, or distant recurrence-free survival. Fifteen patients (4.9%) who underwent NS-BCS had ipsilateral breast tumor recurrence (IBTR), of which 40% were in the nipple-areolar complex and previous surgical sites. One patient (0.9%) who underwent central lumpectomy experienced an IBTR in a different quadrant. NS-BCS showed more local recurrence than central lumpectomy. When deciding whether to spare the nipple during BCS in CLBC, patients should be sufficiently informed about the risk of IBTR.

Prophylactic Salpingo-Oophorectomy and Survival After BRCA1/2 Breast Cancer Resection

Few studies have investigated whether prophylactic salpingo-oophorectomy (PSO) for patients with previously resected breast cancer who carry pathogenic germline BRCA1 or BRCA2 variants is associated with a reduced risk of cancer-specific death. To assess the association of PSO and prophylactic mastectomy (PM) with prognosis after quadrantectomy or mastectomy as primary treatment for patients with BRCA1 or BRCA2 breast cancer. This retrospective cohort study was performed in a single-institution, tertiary referral center. Consecutive patients with invasive breast cancer treated surgically between 1972 and 2019 were recruited and followed up prospectively after they were found to carry the BRCA1 or BRCA2 gene variant. The data analysis was performed between April 2022 and July 2023. Following breast surgery, some patients underwent PSO, PM, or both, whereas others did not. The primary study end point was overall survival as measured by the Kaplan-Meier method. Secondary end points were crude cumulative incidence of breast cancer-specific mortality, ipsilateral breast tumor recurrence (IBTR), contralateral breast cancer, ovarian cancer, and ovarian cancer-specific mortality. Of 480 patients included in the cohort (median age at initial surgery, 40.0 years; IQR, 34.0-46.0 years), PSO was associated with a significantly reduced risk of death (hazard ratio [HR], 0.40; 95% CI, 0.25-0.64; P < .001). This reduction was most evident for patients carrying the BRCA1 variant (HR, 0.35; 95% CI, 0.20-0.63; P = .001), those with triple-negative disease (HR, 0.21; 95% CI, 0.09-0.46; P = .002), and those with invasive ductal carcinoma (HR, 0.51; 95% CI, 0.31-0.84; P = .008). Prophylactic salpingo-oophorectomy was not associated with risk of contralateral breast cancer or IBTR. Initial or delayed PM was associated with a reduced risk of IBTR but not with overall survival or breast cancer-specific mortality. The study findings suggest that PSO should be offered to all patients with BRCA1/2 breast cancer who undergo surgery with curative intent to reduce risk of death. In particular, PSO should be offered to patients with the BRCA1 variant at the time of breast surgery.

Impact of Atypical Hyperplasia at Surgical Margins on breast cancer outcomes in patients treated with neoadjuvant chemotherapy.

Women with atypical hyperplasia (AH) is associated with a higher risk of future breast cancer. However, whether AH found at margins in patients with breast-conserving surgery (BCS) after neoadjuvant chemotherapy (NAC) needs re-excision is not well-defined. The aim of the present study was to evaluate the impact of AH at the surgical margins on the local recurrence and survival outcomes in breast cancer patients treated with NAC and BCS. A retrospective analysis comparing patients who treated with NAC and BCS with AH at the margins to those without AH was performed. 598 patients were included in this study. The 5-year rates of ipsilateral breast tumor recurrence (IBTR) were 4.6% and 6.2% in patients with and without AH, respectively. No significant differences were observed among the two groups in terms of IBTR, DMFS, or OS. HER2 overexpressing breast cancer patients with severe AH at margins have a significantly higher risk of IBTR compared to those without severe AH. Our study suggests that the presence of AH at the surgical margins of BCS in patients who received NAC does not appear to increase the risk of ipsilateral breast cancer. Therefore, there is no need for surgeons to routinely perform additional re-excision of AH found at the margins of BCS in these patients. However, selective re-excision should be considered in certain cases, particularly in patients with HER2 overexpression.

Combining histological grade, TILs, and the PD-1/PD-L1 pathway to identify immunogenic tumors and de-escalate radiotherapy in early breast cancer: a secondary analysis of a randomized clinical trial

BackgroundThe implementation of immunological biomarkers for radiotherapy (RT) individualization in breast cancer requires consideration of tumor-intrinsic factors. This study aimed to investigate whether the integration of histological grade, tumor-infiltrating lymphocytes...

Abstract P4-02-23: Integrating tumor-intrinsic and immunological factors to improve locoregional treatment individualization of high-risk breast tumors

Abstract Background: The influence of the local immune infiltrate on tumor progression is dependent on tumor-intrinsic characteristics. Among highly aggressive subtypes, an immune infiltrate is associated with a favorable prognostic effect. The aim was to investigate whether the integration of histological grade and degree of tumor-infiltrating lymphocytes (TILs) permits improved treatment individualization for clinically high-risk tumors. Methods: The SweBCG91RT trial included 1178 patients with stage I-IIA breast cancer, randomized to breast-conserving surgery with or without adjuvant RT, and followed for a median time of 15.2 years. In total, 8% were treated with systemic therapy. Histological grade and TILs were evaluated on whole-tissue sections by board-certified pathologists. Grade III tumors were compared to grade I and II tumors. TILs were classified as high (&amp;gt;=10%) or low (&amp;lt; 10%). The primary endpoint was ipsilateral breast tumor recurrence (IBTR) within 10 years. Results: In total, 134 (57%) of the 235 grade III tumors had high TIL levels compared to grade I/II tumors where 142 (19.7%) out of 721 tumors exhibited high TIL levels. Grade III tumors with high TILs had a reduced risk of IBTR (HR 0.49, CI 95% 0.26-0.91, p=0.025) compared to grade III tumors with low TILs (HR 1.0). Among grade I/II tumors, high TILs was not prognostic (HR 1.02, CI 95% 0.62-1.68, p=0.95) compared to grade I/II tumors with low TILs (HR 1.0). Grade III tumors with low TILs had a high risk of recurrence without RT (36.2%) and derived benefit from RT (HR 0.16, CI 95% 0.047-0.53, p=0.0029). In contrast, grade III tumors with high TILs had a lower risk of IBTR without RT (14.5%) and did not benefit significantly from RT (HR 0.71, CI 95% 0.26-1.90, p=0.50). Conclusion: Measurements of the local immune infiltrate may improve treatment individualization when integrated with tumor-intrinsic features of aggressivity, such as histological grade. High-risk tumors with an immune infiltrate may be candidates for RT de-escalation. Citation Format: Axel Stenmark Tullberg, Martin Sjöström, Emma Niméus, Fredrika Killander, Dan Lundstedt, Anikó Kovács, Erik Holmberg, Per Karlsson. Integrating tumor-intrinsic and immunological factors to improve locoregional treatment individualization of high-risk breast tumors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-02-23.

Abstract P1-09-03: Impact of BRCA1/2 pathogenic variants on ipsilateral breast tumor recurrence and prognosis following breast-conserving surgery

Abstract Background The risk of ipsilateral breast tumor recurrence (IBTR) and the prognostic outcome of breast-conserving surgery (BCS) for germline BRCA1/2 pathogenic variant (BRCA1/2+) carriers remain controversial. We examined differences in IBTR and prognosis between BRCA1/2+ carriers and non-carriers following BCS for breast cancer. Methods Clinical and pathological data were collected by retrospectively reviewing charts of consecutive patients with stage 0-III breast cancer who underwent genetic testing for germline BRCA1/2 and BCS between 1996 and 2020. Patients with variants of breast cancer-associated genes other than BRCA1/2 were excluded. We compared the incidence of IBTR and prognosis, including overall survival (OS), breast cancer-specific survival (BCSS), and distant recurrence-free survival (DRFS), between BRCA1/2+ carriers and non-carriers. Results We analyzed 551 patients (587 breasts with cancer), including 30 BRCA1+ carriers (32 breasts) and 31 BRCA2+ carriers (32 breasts). The median follow-up was 5.8 years (7.2 and 5.3 years for carriers and non-carriers, respectively). The median age at breast cancer diagnosis was 43 and 46 years for carriers and non-carriers, respectively, indicating younger onset of cancer in carriers (age ≤ 40 years; 46.9% for carriers vs. 27.5% for non-carriers, p = 0.001). In carriers, breast cancer more frequently expressed estrogen receptor-negative (56.2% for BRCA1+ carriers and 15.6% for BRCA2+ carriers vs. 22.0% for non-carriers, p = 0.013), progesterone receptor-negative (62.5% for BRCA1+ carriers and 31.3% for BRCA2+ carriers vs. 29.5%, p = 0.005), nuclear grade III (45.3% for carriers vs. 29.5% for non-carriers, p = 0.010), or a higher Ki-67 index (Ki-67 index &amp;gt; 20) (89.5% vs. 61.8%, p = 0.001) than non-carriers. Moreover, carriers underwent chemotherapy more frequently than non-carriers (62.5% vs. 42.4%, p = 0.002). Cancer stage, tumor size, HER2 status, presence of lymphovascular invasion, and the rate of positive or close surgical margins did not statistically differ between the examined groups. No statistical differences were detected in the number of patients who underwent whole-breast radiotherapy following BCS: 59 breasts in carriers and 503 in non-carriers (92.2% vs. 96.4%). During follow-up, we noted that 9 breasts of BRCA1/2+ carriers (5 [15.6%] for BRCA1+ and 4 [12.5%] for BRCA2+) and 35 breasts (6.7%) of non-carriers developed IBTR (p = 0.035). In an analysis excluding patients who did not undergo radiotherapy, the rate of IBTR remained significantly higher in BRCA1/2+ carriers (p = 0.034) than that in non-carriers. The median time to IBTR was 10.2 years in carriers (10.2 years for BRCA1+ and 8.5 years for BRCA2+) and 3.5 years in non-carriers. Carriers were more likely than non-carriers to exhibit distinct subtypes of recurrent tumors in the ipsilateral breast (66.7% for carriers vs. 19.4% for non-carriers, p = 0.006), occurring in a different quadrant from the primary tumor (50.0% vs. 27.3%, p = 0.215). No significant differences in OS (p = 0.068), BCSS (p = 0.109), or DRFS (p = 0.359) were noted between carriers and non-carriers. Conclusion BRCA1/2+ carriers exhibited a higher risk of IBTR after BCS and a longer time to IBTR than non-carriers. One limitation of the present study is a longer follow-up period for carriers than for non-carriers, as carriers typically underwent long-term observation at our institution; hence, further data accumulation is warranted for validating these findings. Subtypes and quadrants of IBTR were frequently distinct in carriers, indicating the increased incidence of new primary breast cancer. Although the prognosis did not differ between carriers and non-carriers, our results suggest the necessity for long-term intensive breast surveillance of BRCA1/2+ carriers after BCS. Citation Format: Sakiko Kondo, Kumiko Kida, Misato Suzuki, Chika Fukano, Atsushi Yoshida, Naoki Hayashi, Junko Takei, Michiko Yamanaka, Hideko Yamauchi. Impact of BRCA1/2 pathogenic variants on ipsilateral breast tumor recurrence and prognosis following breast-conserving surgery [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-09-03.

Preferences Regarding Breast Surgery Omission Among Patients With Breast Cancer Who Receive Neoadjuvant Chemotherapy.

Currently, several ongoing prospective studies are investigating the safety of breast surgery omission in patients with breast cancer who are exceptional responders to neoadjuvant chemotherapy. However, there is little information about the preferences of these patients regarding omission of breast surgery. We conducted a questionnaire survey to assess preferences regarding omission of breast surgery among patients with breast cancer who had human epidermal growth factor receptor 2-positive or estrogen receptor-negative tumors and good clinical response after neoadjuvant chemotherapy. Patients' estimation of the risk of ipsilateral breast tumor recurrence (IBTR) after definitive surgery or breast surgery omission was also assessed. Of 93 patients, only 22 (23.7%) said they would omit breast surgery. Under the scenario of omitting breast surgery, the 5-year IBTR rate estimated by patients who said they would omit breast surgery was significantly lower (median, 10%) than the rate estimated by patients who preferred undergoing definitive surgery (median, 30%) (p=0.017). The proportion of our surveyed patients who were willing to omit breast surgery was low. Patients who said they preferred to omit breast surgery overestimated the 5-year IBTR risk.

A Novel Nomogram for Predicting Prognosis and Tailoring Local Therapy Decision for Ductal Carcinoma In Situ after Breast Conserving Surgery.

Purpose: We sought to explore the role of nomogram-combined biomarkers, mammographic microcalcification and inflammatory hematologic markers in guiding local therapy decisions in ductal carcinoma in situ (DCIS) subgroups with different ipsilateral breast tumour recurrence (IBTR) risk. Methods: Between January 2009 and December 2018, consecutive patients with DCIS and breast conserving surgery (BCS) were enrolled and randomly assigned to a training cohort (n = 181) and internally validation cohort (n = 78). Multivariate analyses were performed to identify predictors of IBTR. Model performance was evaluated by the concordance index (C-index) and calibration plot. The time-to-event curves were calculated by the Kaplan–Meier methods and compared by the log-rank test. Results: In total, 259 patients were enrolled and 182 of them received whole breast irradiation (WBI). After a median follow-up of 51.02 months, 23 IBTR events occurred in the whole cohort. By multivariate analyses of training cohort, presence of microinvasion, Ki67 index >14%, mammographic-clustered fine linear microcalcifications and neutrophil/lymphocyte ratio before BCS (preop-NLR), >1.1 remained independent risk factors of IBTR to develop a nomogram. The C-indexes of the nomogram were 0.87 and 0.86 in the training and internal validation set, respectively. Calibration plots illustrated good agreement between the predictions and actual observations for 5-year IBTR. Cut-off values of nomogram point were identified as 53 and 115 points, which divided all patients into low-, intermediate- and high-risk groups. Significant differences in IBTR existed between low-, intermediate- and high-risk subgroups (p < 0.01). For the whole cohort and ER-positive tumours, the benefit of WBI was found only in the intermediate-risk subgroup, but not in those with low or high risk. Fourteen out of 23 IBTRs occurred outside the original quadrant and all occurred in the high-risk group. Conclusions: The novel nomogram demonstrated potential to separate the risk of IBTR and locations of IBTR. For the whole cohort and ER-positive tumours, the benefit of WBI was restricted to an intermediate-risk subgroup.

Risk of ipsilateral breast tumor recurrence and contralateral breast cancer in patients with and without TP53 variant in a large series of breast cancer patients

BackgroundThe association between breast cancer patients with a TP53 pathogenic variant and risk of local recurrence and contralateral breast cancer remains largely unknown. MethodsThe study population of 11093 patients was derived from two cohorts at the Breast Center of Peking University Cancer Hospital in China from November 2003, to March 2018. TP53 germline variants were determined for all patients. ResultsIn the study, forty-one (0.37%) carried a TP53 germline pathogenic variant, and 11052 were non-carriers (99.63%). Nineteen TP53 carriers (46.3%) and 4173 non-carriers (37.8%) were treated with breast-conserving therapy (BCT), while the remaining were treated with mastectomy. After a median follow-up of 6.7 years, the rate of ipsilateral breast tumor recurrence (IBTR) in TP53 carriers was significantly higher than that in non-carriers when treated with BCT (21.1% vs 3.8%, P = 0.006). No difference in the rate of IBTR was found between TP53 carriers and non-carriers when treated with mastectomy (0.0% vs 2.6%, P = 1.0). Furthermore, the rate of IBTR in TP53 carriers treated with BCT was significantly higher than that in those treated with mastectomy (21.1% vs 0.0%, P = 0.038). The 10-year cumulative risk of contralateral breast cancer in TP53 carriers was significantly higher than that in non-carriers (17.9% vs 3.6%, hazard ratio (HR) = 7.0, 95% CI: 3.3–14.9, P < 0.001). ConclusionsPatients with TP53 variants have a high risk of IBTR when treated with BCT, and exhibit a very high risk of contralateral breast cancer. TP53 carriers may not be suitable for BCT and prophylactic contralateral mastectomy might be considered.

Effect of neoadjuvant versus adjuvant chemotherapy on ipsilateral breast tumor recurrence after breast-conserving surgery and whole-breast irradiation.

604 Background: Early Breast Cancer Trialists’ Collaborative Group conducted a large meta-analysis and reported that patients who underwent neoadjuvant chemotherapy (NAC) had higher ipsilateral breast tumor recurrence (IBTR) rate than those with adjuvant chemotherapy. However, since the study was conducted with patients treated two decades ago, the results could not reflect the advance in treatments and IBTR rate was much higher than in recent studies, Thus, we investigated the association between chemotherapy settings and IBTR rates in breast cancer patients. Methods: We retrospectively reviewed the data of 5,307 patients who underwent breast conserving surgery followed by whole breast irradiation between January 2004 and December 2018 in a single institution. Patients who underwent mastectomy or omitted chemotherapy were excluded. Results: The 1,473 patients who underwent NAC showed significantly higher IBTR rate than the 3,564 patients who underwent adjuvant chemotherapy (10-year risk: 4.5% vs. 4.0%; log-rank p=0.045, hazard ratio 1.42 [95%CI,1.01-1.99]). The difference was more evident for patients with hormone receptor (HR) positive and human epidermal growth factor receptor-2 (HER2) negative tumor (unadjusted p=0.001, hazard ratio 2.27 [95%CI,1.37-3.74; adjusted p=0.002, hazard ratio 2.80 [95%CI,1.45-5.42]], and the statistical significance was still remained after 1:1 propensity score matching (p=0.026). In contrast, patients with other subtypes did not show significant differences between two groups. Conclusions: Patients who underwent NAC for HR+/HER2- tumors carry increased risk of IBTR than those who underwent adjuvant chemotherapy. Our observation supports the need for considering tumor subtypes in initial treatment. In addition, more intensive surveillance would be needed for patients with HR+/HER2- tumors after NAC.

A propensity score-matched analysis of breast-conserving surgery plus whole-breast irradiation versus mastectomy in breast cancer.

Recent observations regarding long-term outcomes among patients with early-stage breast cancer (BC) who underwent breast-conserving surgery (BCS) plus whole-breast irradiation (WBI) or mastectomy are from a small number of registry-based studies. Therefore, these findings may overestimate differences in survival between the two groups, compared with randomized controlled trials conducted in the 1980s. The aim of this study is to compare long-term outcomes and clinicopathologic characteristics between patients treated with BCS + WBI or mastectomy for BC. We performed a propensity score-matched analysis in a cohort of 9710 patients aged < 70years who underwent BCS + WBI or mastectomy without external radiotherapy for a first primary BC (pT1-2, N0-3a) at the European Institute of Oncology between 2000 and 2008. Patients were matched by propensity score. Median follow-up was 8.4years (interquartile range 6.5-10.2). The cumulative incidence of axillary lymph node recurrence at 10years was lower in the BCS + WBI group [2.4% (95% CI, 1.7-3.3%)] than in the mastectomy group [4.4% (95% CI, 3.5-5.5%)] (P = .0005), and the cumulative incidence of contralateral BC was higher in the BCS + WBI group [3.9% (95% CI, 2.8-5.1%)] than in the mastectomy group [2.5% (95% CI, 1.7-3.4%)] (P = .01). Among the 366 patients with HER2 subtype BC, BCS + WBI was associated with a fivefold higher risk [hazard ratio 4.97 (95% CI, 2.28-10.8)] of ipsilateral breast tumor recurrence (IBTR), compared with mastectomy (P < .0001); however, among patients with other BC subtypes, the rates of IBTR were not statistically significantly different. Patients with HER2 subtype BC (T1-2, N0-3) who underwent BCS + WBI had a statistically significantly higher risk of IBTR than patients who underwent mastectomy. Survival was not statistically significantly different between the groups.

Does breast-conserving surgery with radiotherapy in BRCA-mutation carriers significantly increase ipsilateral breast tumor recurrence? A systematic review and meta-analysis.

Breast-conserving surgery (BCS) is often preferred for localized, small breast cancers, but its safety and efficacy in BRCA-mutation carriers is still controversial. This meta-analysis aimed to determine whether there was any significant difference in the incidence of ipsilateral breast tumor recurrence (IBTR) between BRCA-mutation carriers who underwent BCS and controls with sporadic breast cancer. A PubMed search was conducted through March 2020 to identify studies examining the risk of IBTR after BCS in BRCA-mutation carriers versus controls. The Cochrane risk-of-bias tool was used to assess the risk of bias. The pooled risk ratio (RR) was calculated using the random-effects model. Thirteen studies involving 701 BRCA-mutation carriers and 4788 controls in total were eventually analyzed. In the meta-analysis, IBTR after BCS was significantly higher in BRCA-mutation carriers (RR: 1.589; 95% confidence interval (CI) 1.247-2.024; P < 0.001). Subgroup analysis of the follow-up time found that the RR for IBTR increased as the observation period lengthened (median follow-up: ≧ 7years [RR: 1.505; 95% CI 1.184-1.913] and ≧ 10years [RR: 1.601; 95% CI 1.201-2.132], respectively). However, a qualitative meta-analysis of overall survival in three cohort studies found no evidence to suggest a deterioration in overall survival in patients with BCS. The present study demonstrated that BRCA-mutation carriers with BCS have a higher risk of IBTR, which tended to persist for a long period and become more apparent with longer observation.

Abstract P2-11-07: Mammographic density is associated with increased risk of contralateral breast cancers but not of ipsilateral breast tumor recurrences

Abstract Introduction: The mammographic density (MD), which is the reflection of the proportion of the fibrogladular tissue in breast, is a well-known risk factor for breast cancer development. Recent studies have suggested that MD can also increase the risk of ipsilateral breast tumor recurrence (IBTR) and contralateral breast cancer (CBC) development. However, the data regarding the role of MD on IBTR and CBC is conflicting. To address this issue, we aimed to investigate the relationship between MD and IBTR and CBC in a large cohort of patients treated in a single institution to minimize the heterogeneity of MD assessment and breast cancer treatments.Methods: In this study, we retrospectively reviewed the MD data for 9,011 female breast cancer patients who underwent unilateral breast conserving surgeries between January 2000 and and December 2018 at Seoul National University Hospital. This study was approved by the Institutional Review Board of Seoul National University Hospital (IRB No: 2107-002-1231). The baseline MD for each patient was determined by the digital mammography image obtained within one year since the time of diagnosis. The patients were classified into 'high MD' or 'low MD' based on their baseline MD according to the 5th edition BI-RADS recommendation from the American College of Radiology. Results:The median age of the patients is 49.3 (19-88). Among the 9,011 patients, 6,440 (71.5%) were classified as 'high density' according to their baseline MD. The median follow-up duration was 75.2 months.The cumulative incidence of IBTR in our patient cohort was 2.1% at 10 years. The 'high MD' group experienced more incidences of IBTR with the hazard ratio of 1.44 (95% C.I., 1.07-1.95). Age at the time of diagnosis was also shown to be a significant prognostic factor for IBTR (p&amp;lt;0.001, HR, 0.95; 95%CI, 0.94 - 0.97) and the younger age was significantly associated with high MD (p&amp;lt;0.001). To adjust for the effect of age on IBTR, we stratified the patients according to their age at diagnosis. When the patients were stratified at their median age, the MD did not show significant effect on the development of IBTR. Cox regression analysis also revealed that the degree of MD does not independently predict the risk of IBTR development.For CBC, the cumulative rate at 5 year was 1.4%. Similar to the IBTR, high MD group and young age were significantly risk factors of developing CBC. However, the prognostic impact of high MD was more evident in patients of less than 50 years old. Furthermore, unlike the IBTR, the MD group remained to be independent predictor of CBC after adjusting for other prognostic factors. Conclusion:The degree of MD did not independently predict the risk of IBTR in patients undergoing breast conserving surgery. However, high MD was significantly associated with increased risk of developing CBC especially in younger breast cancer patients. Citation Format: Jong Ho Cheun, Hong-Kyu Kim, Han-Byoel Lee, Wonshik Han, Hyeong-Gon Moon. Mammographic density is associated with increased risk of contralateral breast cancers but not of ipsilateral breast tumor recurrences [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 P2-11-07.

Significance of boost radiotherapy in early invasive ductal breast cancer with ductal carcinoma in situ component under negative surgical margins.

We hypothesize that there is a risk of ipsilateral breast tumor recurrence (IBTR) in surgical margin-free invasive ductal carcinoma (IDC) in the presence of ductal carcinoma in situ (DCIS) component affecting surgical margins in early stage. From 1990 to 2014, 343 patients with IDC in which the DCIS component constitute have received radiotherapy (RT) following breast-conserving surgery (BCS). All patients received whole breast irradiation with a prescribed dose of 50 Gy in 20 fractions (four times a week). This one-arm cohort with boost RT (253 patients) was compared for IBTR with a non-cohort group receiving no boost RT because of freedom from positive margins (90 patients). Median observation months were 98 (boost group) vs 119 (no boost group), respectively. The 15-year local recurrence-free survival (LRFS) rates were 98.5% and 85.6% in the boost and no boost groups, respectively (Cox proportional hazards model univariate analysis; p = 0.013, HR 0.13). Similarly, for other background factors, there was a significant difference in the LRFS between age groups. The 15-year LRFS rate was 91.8% in patients aged 45 years or younger and 94.6% in patients older than 46 years (p = 0.031, HR 0.21), respectively. Only these two factors were independently significant in Cox proportional hazards model multivariate analysis. IBTR risk in margin-free IDC with DCIS component was independently decreased by boost RT in the cohort setting. Tumor size, extensive intraductal component (EIC), boost dose, the presence of lymph node (LN) metastasis and hormonal therapy were not IBTR risk factors in this study.

MRI-Guided APBI Using Brachytherapy PTV Margins is Well Tolerated With Low Ipsilateral Breast Tumor Recurrence Risk

External beam accelerated partial breast irradiation (APBI) utilizes Planning Target Volume (PTV) expansions of 2 to 2.5 cm beyond the surgical cavity to assure treatment of target breast tissue. Decreasing the volume of irradiated breast with external beam accelerated partial breast irradiation (APBI) is a potential way to minimize dose to organs at risk and adverse cosmetic outcomes. Magnetic resonance guided radiation therapy (MRgRT) allows detailed pre-fraction imaging and continuous intrafraction monitoring which allows for external beam APBI treatments using a brachytherapy-style 1 cm surgical bed to PTV margin. We have previously shown that MRgRT APBI results in an average 52% reduction in PTV. In this study we report the outcomes of patients treated with reduced-margin APBI via MRgRT.Patients included women with early stage, node negative breast cancers treated with breast conserving surgery and adjuvant MRgRT APBI from March 2014 to July 2019. PTV was defined as the surgical cavity plus a uniform 1-cm margin of breast tissue (excluding chest wall, pectoral muscles, and 5mm from skin). The PTV received 38.5 Gy in ten fractions over five treatment days. Volumetric MR imaging was acquired prior to each fraction to localize the surgical cavity and a sagittal cine MR imaging during each treatment to monitor intrafraction motion; gating to the surgical bed was used as needed.242 patients were treated with MRgRT APBI with reduced margins. Eighty-one (33.5%) patients had pure DCIS and 161 (66.5%) patients had pT1N0 disease. Seventy-three (90.1%) patients with pure DCIS had hormone sensitive disease and 141 (87.6%) patients with invasive disease had hormone sensitive, her2/neu negative disease. Stratifying by ASTRO APBI Consensus guidelines, 36% of patients were categorized as Cautionary and one patient was Unsuitable solely due to age < 40. At a median follow up of 36 months (range, 14 - 82), two patients (0.8%) had biopsy-proven in-breast tumor recurrence (IBTR), both of whom were successfully salvaged. Per the Aaronson-modified Harris scale, providers reported 100% of patients had good/excellent cosmesis prior to APBI and at last follow-up. Nearly two thirds of patients experienced no acute skin toxicity with the remaining having small regions of grade 1 erythema. There were no observed CTCAEv4.0 grade 3+ toxicities following APBI.APBI with reduced margins using MR-IGRT is safe and has excellent cosmetic outcomes with acceptably low initial rates of IBTR.

Increased Risk for Ipsilateral Breast Tumor Recurrence in Invasive Lobular Carcinoma after Accelerated Partial Breast Irradiation Brachytherapy.

The suitability criteria for accelerated partial breast irradiation (APBI) from the American Brachytherapy Society (ABS), American Society for Radiation Oncology (ASTRO), and The Groupe Européende Curiethérapie European SocieTy for Radiotherapy & Oncology (GEC-ESTRO) have significant differences. This is a single institution retrospective review of 946 consecutive patients with invasive breast cancer who underwent lumpectomy and APBI intracavitary brachytherapy from 2003 to 2018. Overall survival (OS), breast cancer-specific survival (BCSS), relapse-free survival (RFS), and ipsilateral breast tumor recurrence (IBTR) were estimated with Kaplan-Meier method. Median follow-up time was 60.2 months. Median age was 68 years (46-94 years). The majority of patients had estrogen receptor (ER)-positive disease (94%). There were 821 (87%) cases of invasive ductal carcinoma and 68 cases (7%) of invasive lobular carcinoma (ILC). The 5-year OS, BCSS, RFS, and IBTR were 93%, 99%, 90%, and 1.5%, respectively. Upon univariate analysis, ILC (hazard ratio [HR], 4.6; p=.008) and lack of nodal evaluation (HR, 6.9; p=.01) were risk factors for IBTR. The 10-year IBTR was 2.5% for IDC and 14% for ILC. While the ABS and ASTRO criteria could not predict IBTR, the GEC-ESTRO intermediate risk group was associated with inferior IBTR (p=.04) when compared to both low risk and high risk groups. None of the suitability criteria was able to predict RFS. These results show that APBI is an effective treatment for patients with invasive breast cancer. Expansion of the current eligibility criteria should be considered, although prospective validation is needed. Caution is required when considering APBI for patients with ILC. In a large retrospective review of 946 patients with early breast cancer treated with partial mastectomy and accelerated partial breast irradiation (APBI) intracavitary brachytherapy, this study demonstrates durable local control. Patients deemed unsuitable or high risk by the American Brachytherapy Society, American Society for Radiation Oncology, and European Society for Radiotherapy and Oncology guidelines were not at increased risk for ipsilateral breast tumor recurrence (IBTR), suggesting that expansion of the current criteria should be considered. Importantly, however, these results demonstrate that caution should be taken when considering APBI for patients with invasive lobular carcinoma, as these patients had relatively high risk for IBTR (10-year IBTR, 14%).