Review of Current Knowledge of the Germline Genetics of Male Breast Cancer and Its Treatment

Constituting approximately 0.5% of the malignances in men, male breast cancer is a rare disease. While it is increasingly understood that the etiology of male and female breast cancer is genetically distinct, they are prescribed the same treatment.

Current recommendations suggest that genetic counseling, followed by genetic testing, be offered to all men diagnosed with breast cancer. In 4% to 40% of cases, the likely etiology for male breast cancer are pathogenic variants in cancer-predisposing genes. A range of factors contributes to barriers to testing; notably, healthcare professionals lack familiarity with the germane clinical considerations, and therefore, male patients are still less likely to undergo testing than women. By examining the current understanding of the germline genetic background of male breast cancer and its influence on how patients and their families are managed, Campos and colleagues attempted to delineate strategies to overcome this educational gap.

Currently, male and female breast cancer are thought to be genetically distinct. Genetic and epigenetic features of female and male breast cancer are not shared, based on a growing body of evidence from clinical research studies. While male breast cancer is rare, it is recognized that a genetic predisposition to form tumors plays a significant role. In cases of BRCA1 and BRCA2, inherited germline variants account for approximately 2% and 10% of breast cancer cases, respectively, and for men harboring BRCA1 and BRCA2 mutations the lifetime risk of breast cancer is 1.2% and 6.8%, respectively. In the case of female breast cancer, pathogenic mutations in other breast cancer genes such as PALB2 and CHEK2 mutations have also been recently associated with an increased risk of male breast cancer. The rarity of male breast cancer has contributed to data limitations that would enable a fuller understanding of the relative risk and contribution of recently identified moderate penetrance genes of female breast cancer for male breast cancer predisposition.

Source:

Campos FAB, Rouleau E, Torrezan GT, et al. Genetic landscape of male breast cancer. Cancers (Basel). 2021;13:3535.