While it is not common, breast cancer in males does occur. Estimates are that for every 100-200 women diagnosed with breast cancer, there is one man diagnosed. In men the cancer often presents at a later age, since it's unaffected by childbirth or menopause. In men the cancer is also most often estrogen receptor positive.
Men do not typically perform monthly breast self exams so it's not always discovered in the early stages. Most often, men will go to their doctor or health professional with a concern over breast enlargement (gynecomastia) and the disease is then discovered. Experts agree that family history plays a part in the development of breast cancer in men. The presence of the BRCA2 gene plays a part as well. Finally, doctors need to be aware that men have different treatment needs women and these needs are not well known since they are not seen as often in oncology practices.