Clinicopathological and Immunohistochemical Characteristics in Male Breast Cancer: A Retrospective Case Series.

backgroundDue to its rarity, male breast cancer (mBC) remains an inadequately characterized disease, and current evidence for treatment derives from female breast cancer (FBC).

methodsWe retrospectively analyzed the clinicopathological characteristics, treatment patterns, and outcomes of mBCs treated from 2000 to 2013.

resultsFrom a total of 97 patients with mBC, 6 (6.2%) with ductal in situ carcinoma were excluded, and 91 patients with invasive carcinoma were analyzed. Median age was 65 years (range: 25-87 years). Estrogen receptors were positive in 88 patients (96.7%), and progesterone receptors were positive in 84 patients (92.3%). HER-2 was overexpressed in 13 of 85 patients (16%). Median follow-up was 51.5 months (range: 0.5-219.3 months). Five-year progression-free survival (PFS) was 50%, whereas overall survival (OS) was 68.1%. Patients with grades 1 and 2 presented 5-year PFS of 71% versus 22.5% for patients with grade 3 disease; 5-year OS was 85.7% for patients with grades 1 and 2 versus 53.3% of patients with grade 3. Ki-67 score >20% and adjuvant chemotherapy were also statistically significant for OS on univariate analyses. Twenty-six of 87 patients (29.8%) experienced recurrent disease and 16 of 91 patients (17.6%) developed a second neoplasia.

conclusionMale breast cancer shows different biological patterns compared with FBC, with higher positive hormone-receptor status and lower HER-2 overexpression. Grade 3 and Ki-67 >20% were associated with shorter OS. IMPLICATIONS FOR PRACTICE: There is little evidence that prognostic features established in female breast cancer, such as grading and Ki-67 labeling index, could be applied to male breast cancer as well. This study found that grade 3 was associated with shorter overall survival and a trend for Ki-67 >20%; this could help in choosing the best treatment option in the adjuvant setting. Many questions remain regarding the impact of HER-2 positivity on survival and treatment with adjuvant anti-HER-2 therapy. Regarding metastatic male breast cancer, the results suggest that common regimens of chemo-, endocrine and immunotherapy used in female breast cancer are safe and effective for men. Male breast cancer patients show a higher incidence of second primary tumors, especially prostate and colon cancers and should therefore be carefully monitored.