Abstract
INTRODUCTION: A retrospective registry-based cohort study was conducted to examine the risk of second primary cancer following the occurrence of breast cancer in males. METHODS: Data obtained from the California Cancer Registry in the period 1988 to 2003 included 1,926 men aged 85 years and younger diagnosed with a first primary breast cancer. Person-year analysis was applied to determine the risk of second primary cancers after the occurrence of a first primary breast cancer. The effects of age, race, and time since the first breast cancer diagnosis were assessed. RESULTS: Of the 1,926 male breast cancer cases, 221 (11.5%) developed a second primary cancer. Men with first incidence of breast cancer have a significantly higher risk of second cancer (standardized incidence ratio (SIR) = 1.16, 95% confidence interval (CI) = 1.01-1.32). The risk of a second site-specific cancer is elevated for breast cancer (SIR = 52.12, 95% CI = 31.83-80.49), cutaneous melanoma (SIR = 2.98, 95% CI = 1.63-5.00) and stomach cancer (SIR = 2.11, 95% CI = 1.01-3.88). There is a general tendency towards higher risks of second malignancies among younger men compared to older men and the risk increased with the passage of time. CONCLUSION: Male breast cancer patients should be monitored carefully for the occurrence of second primary cancers, especially a second primary breast cancer.