Are there biologic differences between male and female breast cancer explaining inferior outcome of men despite equal stage and treatment?!

Abstract

Reasons for inferior outcome of male compared to female breast cancer are still under debate. Therefore, we retrospectively analyzed male breast cancer cases to figure out possible treatment- and gender-related differences. A total of 40 men (median age 62 years) were curatively treated with mastectomy and postoperative radiotherapy from 1982-2007. They presented predominantly in stages II and IIIb. Postoperative radiotherapy was applied with doses of 1.8-2.5 Gy to a median of 50 Gy including regional lymphatics in 22 patients. Adjuvant systemic treatment consisted of chemotherapy (22.5%) and antihormonal treatment (55%). For reasons of comparison, we estimated outcome of a virtual female matched cohort for no/equal to men/optimal adjuvant treatment with the Adjuvant!Online(®) 8.0 algorithm. After a median follow-up of 47 months, the estimated 5-year local control rate was 97%, disease-free and distant metastasis-free survival rates reached 79% and 82%, respectively. With update of survival data by tumor registry, mean overall survival reached 120 months with 5- and 10-year overall survival rates of 66% and 43%, respectively. Predominant prognostic factor was T-stage for overall survival (T1/2 vs. T4: > 80% vs. 30%). The generated virtual matched cohorts of women with equal characteristics reached superior 10-year-overall survival for no/equal to men/optimal adjuvant treatment with 55/59/68%. Compared to historical and virtual matched cohorts of women, male breast cancer patients had inferior outcome despite of equal stage and treatment which indicates that biological differences (of tumor or population) may contribute to worse prognosis.