The general age of onset for male breast cancer is between 65 and 67 years old, which is about five to ten years later than the onset age for female breast cancer. Male breast cancer is a relatively rare malignancy, accounting for only 0.6% to 1% of all breast cancer cases, meaning that out of 100 breast cancer patients, approximately one is male. The development of male breast cancer is caused by multiple factors, which may include genetic factors, environmental influences, and also related to levels of hormone secretion from the endocrine system.