Background: Male breast cancer (MBC) comprises 1% of all breast cancers and less than 1% of cancer cases in men. After a diagnosis of MBC, men are at risk of developing a second primary cancer, particularly a second primary breast cancer. The objective of this study is to analyze the characteristics of the population of men diagnosed with a second malignancy, specifically a second MBC.
Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, 4,873 male patients diagnosed with invasive or in situ breast cancer from 1973 to 2004 were identified and data from patients who developed a second MBC were reviewed. Additional non-breast primary cancer diagnoses were also recorded.
Results: A review of 4,966 records corresponding to 4,873 patients revealed 4,462 invasive and 504 in situ breast cancer events. Of the 4,873 patients, 93 (1.9%) were identified with a second MBC. Among the 4,873 patients with MBC, 1,001 (21%) have other non-breast primary cancer diagnoses recorded in the SEER registry.
Conclusions: Although MBC is uncommon, these patients are at risk of a contralateral breast cancer and second primary non-breast cancers. Our findings support that men with breast cancer would benefit from continued long-term surveillance for breast cancer and appropriate screening for non-breast cancers.