A pilot study of male breast cancer in the Veterans Affairs healthcare system.

Background: We report our findings on a hospital-based retrospective pilot cohort with case-controls study, which we carried out to examine genetic, environmental, and occupational risk factors in men with breast cancer.
Methods: 86 men with breast cancer were diagnosed in eight VA medical centers that agreed to collaborate on this project. A case-control analysis was conducted on a subset of the male breast cancer cases (n = 44) and age- and ethnicity-matched controls (n = 77). We compared host characteristics, comorbidities, and medications intake between cases and controls by using Chi-square analysis and Fisher's exact test.
Results: The descriptive analysis showed that the majority of veterans with male breast cancer were non-Hispanic white (60%), older than 65 years at diagnosis (56%), and more likely estrogen receptor positive (45%). World War II veterans represented the largest group (22%), followed by the Vietnam era veterans (10%). Thirty-three percent reported a positive family history of cancer, while 18% had another primary cancer diagnosis. Prior alcohol (43%) and tobacco use (56%) was substantial among these patients. Twenty percent of patients were overweight or obese and 55% had comorbid diseases with heart disease being the most prevalent, followed by diabetes mellitus. The case-control analysis yielded a significantly greater proportion of cases with gynecomastia (p < 0.0001), a positive family history of cancer (p = 0.0028), history of antibiotic use (p = 0.0112), and history of tobacco use (p = 0.0143) compared to controls.
Conclusion: The findings of this hospital-based pilot study indicate case-control differences in gynecomastia and family history of cancer. The pilot study lacked sufficient power to determine a true association between the variables of interest and warrants a large-scale collaborative study between the VA medical centers.