Male breast cancer in the veterans affairs population: a comparative analysis

The incidence of male breast cancer (MBC) continues to rise. The Veterans Affairs (VA) Central Cancer Registry (VACCR) provides a unique source for the study of MBC. The objective of this retrospective analysis was to compare the characteristics and outcome of patients with MBC and patients with female breast cancer (FBC) in the VA population.

VACCR data were used to analyze the database of VA patients who had breast cancer diagnosed between 1995 and 2005. It includes 120 VA medical centers. Primary site codes were identified for breast cancer (500-508). Data were entered and analyzed using biostatistical software.

In total, 3025 patients' records were reviewed, and 612 patients who had MBC were compared with 2413 patients who had FBC. The mean age at diagnosis was 67 years for patients with MBC and 57 years for patients with FBC (P < .005). More patients with MBC were black, and patients with MBC presented with higher disease stage and more lymph node-positive disease. The dominant histology in MBC was ductal carcinoma. No difference in grade or laterality was observed. Estrogen and progesterone receptor-positive tumors were more common in MBC compared with FBC. Overall, patients with MBC received less chemotherapy, whereas no statistical difference was observed in the use of hormone treatment. The median overall survival for patients who had MBC was 7 years compared with 9.8 years for patients who had FBC (log-rank test; P < .005). There was no statistically significant difference in median survival for patients with stage III disease and stage IV disease. However, the median survival differed significantly for patients with stage I disease and stage II disease. In lymph node-negative patients, the median survival was 6.1 years for patients with MBC and 14.6 years for patients with FBC (P < .005), whereas the median survival did not differ significantly in lymph node-positive patients. Using Cox regression analysis age, sex, clinical stage, and lymph node status were independent prognostic factors for survival, whereas race, histology, and grade were not.

To the authors' knowledge, this is the largest series of MBC and FBC to date in the veterans population. The results suggested the presence of differences in the biology, pathology, presentation, ethnicity, and survival between patients with MBC and patients with FBC in the VA population. It is noteworthy that the survival of patients with MBC was inferior for those with early-stage disease and lymph node-negative tumors, suggesting that there are differences between the sexes in the pathogenesis and biology of breast cancer. In patients with hormone receptor-positive MBC, survival was inferior despite similar hormone treatment practices between MBC and FBC. This observational study calls for a better understanding of this disease that would allow new opportunities for specific therapeutic intervention.