Male breast carcinoma in United States: Survival rate and determinants of prognosis.

Abstract

32 Background: Male breast cancer (MBC) is rare and accounts for less than 1% of all cancers in men. It causes significant morbidity and mortality due to late diagnosis. The primary objective of our study is to update information about the receptor status, pathology, survival rates, and prognostic factors for MBC. Our secondary objective is to determine racial differences in survival of MBC and compare tumor characteristics with female breast cancer (FBC) patients. Methods: We analyzed a retrospective cohort of breast cancer patients included in National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) from 1990 to 2007. Differences between patient and disease characteristics at the time of diagnosis among MBC and FBC patients were compared using chi-square test. Overall survival was estimated using Kaplan-Meier method. Cox proportional hazards regression model was used to determine the independent variables that affect survival. Results: We included 2,475 men and 393,259 women with breast cancer in our analysis. Median age at diagnosis was higher in men compared to women (67 vs 61years). Men had more frequent lymph node involvement (32% vs. 22%), ER positivity (66% vs. 57%) and PR positivity (57% vs. 49%) breast cancer than women (P<0.001). Overall median survival in MBC was 9 years, 5-year survival was 63% and 10-year survival was 43%. Increased age, larger tumor size, higher grade, lymph node involvement, ER and PR negative status were significantly associated with decreased survival in univariate analysis (P <0.05). In multivariate analysis, age > 65 years at the time of diagnosis, larger tumor size, positive lymph node status, ER negative status and poorly differentiated grade were associated with decreased survival (P <0.02). However PR status was not a significant predictor of survival. The median survival in African American males was lower as compared to Caucasians (7.08 vs. 9.2 yrs.) (P=0.02). Conclusions: Male breast cancer differs from female breast cancer in important biological characteristics with a higher age at diagnosis and frequent lymph node involvement. Age greater than 65 years, tumor size, grade, lymph node involvement and ER status of the tumor are independent predictors of survival in MBC.