Table 1.
Suggested risk factors for male breast cancer
| Risk factor | Explanation |
|---|---|
| BRCA2 | BRCA2 mutations are associated with most inherited MBC |
| Klinefelter syndrome | Hereditary condition characterised by the 47XXY karyotype, which is consistently associated with MBC |
| Androgen receptor mutation | Germline mutations in AR predispose to MBC |
| CYP17 | Encodes cytochrome P450c17α, an enzyme involved in oestrogen and androgen biosynthesis |
| Cowden syndrome | Autosomal-dominant cancer susceptibility syndrome caused by germline mutation in the PTEN gene |
| CHEK2 | CHEK2*1100delC variants may increase risk of MBC by 10-fold |
| Endogenous oestrogen levels | Increased oestrogen levels as a result of obesity, male-female transsexuals and liver cirrhosis are all associated with MBC |
| Testicular disorders | Cryptorchidism, mumps orchitis, orchiectomy, congenital inguinal hernia and testicular injury are associated with MBC |
| Physical inactivity | Lack of exercise is associated with increased risk of MBC |