Abstract P1-07-09: Retrospective cohort study of patients (pts) diagnosed with breast cancer (BC) <40 yrs: 2000 to 2015⟨

Abstract

Abstract Background Young women (<40 yrs) with breast cancer (YWBC) account for 7-12% of BC diagnoses. BC is the leading cause of cancer death in this group (G). Age-specific data on outcome and appropriate treatment (Rx) are lacking. YWBC appear to have more biologically aggressive subtypes and a higher risk of relapse and death. We studied the clinico-pathological (ClinPath) characteristics in YWBC, examining how outcomes/Rx have evolved. Methods YWBC were identified from pathology databases at 2 tertiary centers. Pts were divided into 2 cohorts: BC diagnoses from 2000-2007 (G1) and 2008-2015 (G2). ClinPath and Rx data were retrieved from clinical, radiology and histology databases. Statistical analysis was performed using SPSS. Results We identified 347 pts. Tumor features are shown in Table I. Median age is 36 (23-39). By histology, 90.8% (n=315) had invasive ductal carcinoma, 53.1% (n=181) had Grade III BC and 56.3% (n=171) had lymphovascular invasion. Pregnancy-associated BC occurred in 10.7% (n=34). Mastectomy (MX) was performed in 53% (n=176) and axillary lymph node clearance (ALNC) in 63.8% (n=192 [G1: 84.3% vs. G2: 48.6%, p<0.001]). Table 1Tumor features Group 1 (n=149)Group 2 (n=198)Total (n=347)p-valueMedian tumor size (mm) 252222.5p=0.115Node positivity 88 (60.3%)100(51.5%)188 (55.3%)p=0.109Median node count 4 (1-44)1 (1-30)2 (1-44)p<0.001StageI 99(29%) II 148 (43.3%) III 70 (20.5%) IV 23(7.3%) Biomarker status*ER+/HER2-76 (53.1%)120 (60.6%)196 (56%)p=0.086 HER2+41 (28.7%)45 (22.8%)86 (27%)p=0.031 Triple negative (TN)26 (18.2%)33 (16.8%)59 (17%)p=0.291* Missing data n=6 Rx characteristics are shown in Table 2. 85 pts received neo-adjuvant therapy (NAT); 48.3% (n=41) ER+/HER2-, 27% (n=23) HER2+ and 24.7% (n=21) TNBC. Pts receiving NAT in G2 trended towards improved pCR rate (G2: 24.6% vs G1: 8.3%, p=0.057). Endocrine Rx alone was received by 9.8% (n=22); 13.6% (n=18) in G2 vs 4.3% (n=4) in G1. OncotypeDx(ODx) was used in 23 pts (14.9%) (median score 17), 1 had a DR (ODx Score = 18). Table 2Tx characteristics n=347 Chemotherapy Total300(86.4%) NAT85 (28.3%)Pathological Complete Response (pCR)* pCR (n=16, 19.8%)No pCR (n=65, 80.2%) ER+/HER2-18.8%(n=3)53.9% (n=35) HER2+/ER+18.8%(n=3)13.8% (n=9) HER2+/ER-31.2% (n=5)9.2% (n=6) TNBC31.2%(n=5)23.1%(n=15)Local relapse 1 (6.2%)1(1.5%)Distant relapse (DR) 022(33.8%)*Data incomplete n=4 DR occurred in 50 pts (16%), including 13 (20.3%) HER2+ pts. Of note, 92.3% (n=12) of these were in G1. Relapse rates (RR) in TN and ER+/HER- pts were 19.6% (n=11) and 13.7% (n=26) respectively. There was a higher RR in G1 (34.8% vs 11.4%, p<0.001). Overall survival in pts with stage IV dx was 32 mos in G1 and 48 mos in G2. Conclusion In line with existing data, locally advanced dx is more prevalent in YWBC. MX and ALNC rates were high and most received multimodal Rx. The extent of axillary surgery declined. Pts in G2 had lower volume BC at diagnosis suggesting increasing awareness. TN and HER2+ subtypes accounted for a slightly higher proportion of BC cases. Pts with PCR had better outcomes. Only 16% relapsed with metastatic dx. The impact of HER2 Rx is highlighted by reduced RR in HER2+ G2 pts. Outcomes were unchanged in pts with ER+/HER2- and TNBC. These remain a priority for future research. Citation Format: Greally M, Kielty J, Das G, Malouf C, O'Riordan L, Coleman N, Quinn C, McDermott E, Gullo G, Kelly C, Crown J, Prichard R, Walshe J. Retrospective cohort study of patients (pts) diagnosed with breast cancer (BC) <40 yrs: 2000 to 2015⟨. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-09.