Collins, LC

Abstract Background: Synchronous bilateral breast cancer is rare, with reported incidence from 0.3-12%; the incidence and pattern of bilateral breast cancer among younger women is unknown. Here we report the incidence and phenotypes of bilateral breast cancer in women ≤40 years of age enrolled in the Young Women's Study (YWS) cohort. Methods: The YWS is a multi-center, prospective cohort study that enrolled women with newly diagnosed breast cancer at age ≤40 years from 2006-2016. Those with synchronous bilateral breast cancer (in-situ and/or invasive) formed our study cohort. Disease characteristics and treatment were obtained by medical record review. Central pathology review was performed to capture histologic features and categorize the tumor phenotype as either luminal A (hormone receptor (HR)+, HER2-, grade 1 or 2), luminal B (HR+, HER2+, or HER2- and grade 3), HER2-type (HR-, HER2+), or triple negative (TNC; HR/HER2-). Tumor phenotypes of bilateral breast cancers were compared and evaluated for concordance. Results: Among 1302 patients enrolled in the YWS, 20 (1.5%) patients presented with bilateral disease, with median age of diagnosis of 38 years (range 18-40). The majority of patients (13 (65%)) presented with unilateral symptoms and contralateral disease was identified on subsequent imaging. 12 (60%) reported a positive family history of breast cancer and 17 (85%) underwent genetic testing; resulting in the identification of 6 mutation carriers (2 BRCA1, 3 BRCA2, 1 TP53). The majority of patients (15 (75%)) underwent bilateral mastectomy, 1 underwent unilateral mastectomy with contralateral lumpectomy, and 4 underwent bilateral lumpectomy. On pathology, 2 patients had bilateral in-situ disease, 5 had unilateral invasive and contralateral in-situ disease, and 13 had bilateral invasive disease. Of those with bilateral invasive disease, all had concordant tumor histology (92% ductal, 8% ductal and lobular), 10 (77%) patients had bilateral luminal tumors and when fully characterized 6 were of the same luminal type. Only one patient had bilateral basal-like breast cancer. Patient ID ERPRHer2 amplifiedGradePhenotype1Left++-2Luminal A Right++-3Luminal B3Left++-3Luminal B Right++-3Luminal B6Left++-3Luminal B Right++-3Luminal B9Left++-2Luminal A Right++-2Luminal A10Left+++3Luminal B Right++-2Luminal A12Left+--3Luminal B Right+--2Luminal A13Left---NABasal-like Right++-NALuminal A or B14Left+++2Luminal B Right++-3Luminal B15Left++-3Luminal B Right+++3Luminal B16Left+++3Luminal B Right--+NAHEr2-type17Left---3Basal-like Right---3Basal-like19Left++-2Luminal A Right++-3Luminal B20Left++-1Luminal A Right++-2Luminal A Conclusions: Among a large cohort of young women, only 20 (1.5%) had bilateral disease, and the majority of the invasive tumors were of the luminal phenotype, yet frequently differed by grade or HER2 status; supporting the need for thorough pathologic evaluation of bilateral disease to determine risk and tailor treatment. Overall the low incidence of bilateral disease and preponderance of the luminal phenotype in this population is reassuring. Citation Format: Pak LM, Rosenberg SM, Ruddy KJ, Tamimi RM, Peppercorn J, Schapira L, Borges VF, Come SE, Warner E, Snow C, Collins L, King TA, Partridge AH. Tumor phenotype and concordance in synchronous bilateral breast cancer in young women [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-22-03.

Abstract Background: The 21-gene Recurrence Score (RS) assay is prognostic among women with early-stage estrogen receptor (ER) positive and human epidermal growth factor receptor 2 (HER2) negative breast cancer (BC) and is used to select patients for chemotherapy (CT). Young women (age <40) have represented a minority in studies evaluating gene expression assays, including TAILORx, and additional data in young women are needed. Methods: In the Young Women's Breast Cancer Study, a prospective cohort study of women diagnosed with BC at age <40 enrolling between 2006-2016 (N=1302), we identified those with stage I-III ER+/HER2- BC. Disease and treatment information were obtained through serial surveys and medical record review. The RS was performed on banked specimens for those not tested clinically. Distant recurrence free interval (DRFI), defined as distant recurrence or BC specific death, by risk group was assessed using Cox regression and Kaplan-Meier survival estimates. Outcomes by receipt of CT were explored in the RS 11-25 group, and due to small number of events, reported descriptively. Results: Among eligible women (N=577), 189 (33%) had undergone RS testing and 320 (56%) had banked specimens sufficient for testing. Median follow-up was 6 years. Median age at diagnosis was 37, most had N0 BC (300/509, 59%), and the majority had RS 11-25 (306/509, 60%). RS result was significantly associated with DRFI in N0 BC, with hazard ratio (HR) (95% CI) of 0.29 (0.07,1.30) and 0.21 (0.09,0.50) for RS<11 and RS 11-25, respectively, relative to RS>26 (and trended towards significance in N1 BC). Results were similar using conventional RS groups. Among women with N0 BC and RS 11-25, 44% received CT, with two events in the 86 receiving CT (2.3%) and 6 events in the 109 without CT (5.5%); 5/8 (63%) occurred in those with RS 20-25. Table 1 N0N1Total Cohort N%N%N% 3005916332509100Median Age37.137.537.2Tumor Stage T120869694229358T28227784817635T3103159357T4001151Grade I4716855711II16555794926652III8829754618536Not assessed 1 1 PR status by IHC Negative (<1%)2071710398Positive (>=1%)280931469047092Chemotherapy No1414712715430Yes159531519335570Ovarian Suppression No263881499145289Yes37121495711TAILORx RS Groups RS <1133111495411RS 11-2519565885430660RS >=267224613714929Conventional RS Groups RS <1812742543319939RS 18-3012542694221142RS >=31481640259919 Table 2 6-year freedom from distant recurrence or breast cancer deathDRFI HR (95% CI) N0N1N0N1TAILORx RS Groups RS <1194.4%92.3%0.29 (0.07,1.30)0.21 (0.03,1.61)RS 11-2596.9%85.2%0.21 (0.09, 0.50)0.55 (0.27,1.12)RS >=2685.1%71.3%RefRefConventional RS Groups RS <1897.5%85.9%0.19 (0.06,0.59)0.31 (0.13,0.74)RS 18-3093.1%87.3%0.39 (0.16,1.00)0.32 (0.14,0.73)RS >=3186.4%62.8%RefRef Conclusions: The RS is prognostic among young women with node-negative and node-positive BC, and is a valuable tool for risk stratification. Disease outcomes among young women with N0 disease and RS 11-25, a minority of whom received CT, are very good. Evaluation of the effect of ovarian suppression/CT-induced amenorrhea by RS/treatment strata is ongoing. Citation Format: Poorvu PD, Gelber SI, Rosenberg SM, Ruddy KJ, Tamimi RM, Collins LC, Peppercorn J, Schapira L, Borges VF, Come SE, Warner E, Jakubowski DM, Russell C, Winer EP, Partridge AH. Prognostic impact of the 21-gene recurrence score assay among young women with node-negative and node-positive ER+/HER2- breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-07.