Breast cancer in men is rare . Although it shares many similarities with cancer of the breast in women, there are also important differences .
EPIDEMIOLOGY AND RISK FACTORS
In the United States, approximately 2140 new cases of breast cancer in men are diagnosed annually, and 450 deaths occur; this represents less than 0.5 percent of all cancer deaths in men annually . By contrast, in Tanzania and areas of central Africa, breast cancer accounts for up to 6 percent of cancers in men .
In the United States, the ratio of female to male breast cancer is approximately 100:1 in whites, but lower (70:1) in blacks [2,3]. Blacks also have a poorer prognosis, even after adjustment for clinical, demographic, and treatment factors. (See 'Racial disparities' below.)
The median age of onset of breast cancer in men is 65 to 67, approximately 5 to 10 years older than in women [2,4-9]. Like female breast cancer, the incidence of breast cancer in men has been increasing; one report suggests that incidence has increased 26 percent over the past 25 years .
Risk factors — Although the majority of men with breast cancer have no identifiable risk factors, several have been identified, many related to hormone levels. Many of these risk factors are the same as in women, including family history, Jewish ancestry, obesity, low levels of physical activity, prior chest wall irradiation, and benign breast disease [3,11]. (See "Factors that modify breast cancer risk in women".)