Abstract P6-19-05: Clinical characteristics and survival of patients with male breast cancer: The Mayo Clinic experience
Authors: S Yadav, RA Leon-Ferre, RE Jimenez, JR Hawse, TJ Hieken, FJ Couch, JC Boughey, KJ Ruddy
Journal: Cancer Research (2019)

Abstract Background: Male breast cancer (MBC) is rare, and usually managed by extrapolation from female breast cancer. We report on the characteristics and survival outcomes of MBC patients from Mayo Clinic Rochester (MCR). Methods: Medical records of MBC patients treated at MCR during a 25-year period (1990-2015) were reviewed. Demographic variables, tumor characteristics, recurrences, and overall survival (OS) were collected. Progression free survival (PFS) and OS were estimated by the Kaplan-Meier method. Multivariate Cox-proportional hazard regression was used to identify predictors of OS. Results: One hundred sixty-seven patients were included in the final analysis, with a median follow-up of 58 months after diagnosis. Baseline characteristics are presented in Table 1. Eighty percent of patients with ER-positive tumors received endocrine therapy. Among men with stage I-III disease, approximately 90% underwent mastectomy, and 44% received adjuvant chemotherapy. The 5-year locoregional and distant recurrence rates for patients with stage I-III disease were 4.4% and 21.5%, respectively. The 5-year PFS and OS for patients with stage I-III disease were 65.5% and 80.1%, respectively. In a multivariate analysis assessing predictors of OS in patients with stage I-III disease, older age (HR 1.05; 95% CI: 1.02 – 1.09), stage II (HR 11.06; 95% CI: 3.84 – 31.85) or stage III disease (HR 14.74; 95% CI (3.99 – 54.45), and omission of surgery (HR 45.33; 95% CI: 3.97 – 517.32) were associated with poorer OS, while endocrine therapy (HR 0.21, 95% CI: 0.09 – 0.51) was associated with better OS. ER, PR, HER2 and grade were not independently prognostic. The median OS for stage IV patients was 10 months, though this 11-man cohort was too small to allow assessment of prognostic factors in advanced male breast cancer. Conclusions: MBC remains an understudied condition. Prognostic factors in this stage I-III disease are consistent with those identified in other MBC retrospective cohorts. Prospective studies are needed to better understand the unique clinical features of MBC, and to improve outcomes, particularly for advanced disease. Table 1:Baseline characteristics N=167 Median age at diagnosis (Years)64.4 Ethnicity/Race: Caucasian131 (78.4%)African American4 (2.4%)Other or unknown32 (19.2%) Overall AJCC 7th edition stage: Stage I39 (23.4%)Stage II80 (47.9%)Stage III32 (19.2%)Stage IV11 (6.6%)Unknown5 (3.0%) Grade: 18 (4.8%)247 (28.1%)3101 (60.5%)Unknown12 (7.1%) ER status: Negative8 (4.8%)Positive153 (91.6%)Unknown6 (3.6%) PR status: Negative17 (10.2%)Positive141 (84.4%)Unknown9 (5.4%) HER-2 status: Negative70 (41.9%)Positive12 (7.2%)Unknown85 (50.9%) Citation Format: Yadav S, Leon-Ferre RA, Jimenez RE, Hawse JR, Hieken TJ, Couch FJ, Boughey JC, Ruddy KJ. Clinical characteristics and survival of patients with male breast cancer: The Mayo Clinic experience [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 P6-19-05.