Sex
Men have a much lower risk of developing breast cancer than women. In developed countries, about 99% of breast cancer cases are diagnosed in women; in a few African countries, which represent the highest incidence of male breast cancer, men account for 5–15% of breast cancer cases. The rate of breast cancer in men appears to be rising somewhat.
Men diagnosed with breast cancer tend to be older than women with breast cancer. They are more likely to be diagnosed with hormone-receptor positive tumors, with about six out of seven cases being estrogen-receptor positive. The overall prognosis is worse for men than for women.
Read more about this topic: Risk Factors For Breast Cancer