Male breast cancer

Male breast cancer (MBC) is a cancer in males that originates in their breasts. Males account for less than 1% of new breast cancers with about 20,000 new cases being diagnosed worldwide every year. Its incidence rates in males vs. females are, respectively, 0.4 and 66.7 per 100,000 person-years (person-years is the number of new cases divided by the product of the relevant population's size multiplied by the average number of years of observation, i.e. new cases ÷ [population × years]). The worldwide incidences of male as well as female breast cancers have been increasing over the last few decades. Currently, one of every 800 men are estimated to develop this cancer during their lifetimes. Because it has a far lower incidence in males and because large-scale breast cancer studies have routinely excluded males, current knowledge of male breast cancer is far less than female breast cancer and often rests on small, retrospective, single-center studies. Consequently, the majority of strategies for evaluating and treating MBC have been adopted from those used for female breast cancer. However, MBC appears to have some features that warrant clinical approaches differing from those for female breast cancer. Features of male breast cancers that differ from those in females include variations in their presentations, associations with other diseases, associations with non-medical predisposing conditions, expressions of key breast cancer-related hormones, causes (including frequency and forms of genetic alterations), tumor types, and treatments. The handling of MBC has typically followed many of the same protocols established for female breast cancer. Female breast cancer most often presents as a mass found on routine screening mammography or self-examination. It may have attracted attention by its size, tenderness, painfulness, or, less commonly, nipple discharge (which may be bloody), nipple retraction, breast swelling, or appearance of a skin lesion such as an ulcer.