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Breast can­cer is can­cer that devel­ops from breast tis­sue. Signs of breast can­cer may include a lump in the breast, a change in breast shape, dim­pling of the skin, flu­id com­ing from the nip­ple, or a red scaly patch of skin. In those with dis­tant spread of the dis­ease, there may be bone pain, swollen lymph nodes, short­ness of breath, or yel­low skin. Risk fac­tors for devel­op­ing breast can­cer include: female sex, obe­si­ty, lack of phys­i­cal exer­cise, drink­ing alco­hol, hor­mone replace­ment ther­a­py dur­ing menopause, ion­iz­ing radi­a­tion, ear­ly age at first men­stru­a­tion, hav­ing chil­dren late or not at all, and old­er age. About 5–10% of cas­es are due to genes inher­it­ed from a per­son­’s par­ents, includ­ing BRCA1 and BRCA2 among oth­ers. Breast can­cer most com­mon­ly devel­ops in cells from the lin­ing of milk ducts and the lob­ules that sup­ply the ducts with milk. Can­cers devel­op­ing from the ducts are known as duc­tal car­ci­no­mas, while those devel­op­ing from lob­ules are known as lob­u­lar car­ci­no­mas. In addi­tion, there are more than 18 oth­er sub-types of breast can­cer. Some can­cers devel­op from pre-inva­sive lesions such as duc­tal car­ci­no­ma in situ. The diag­no­sis of breast can­cer is con­firmed by tak­ing a biop­sy of the con­cern­ing lump. Once the diag­no­sis is made, fur­ther tests are done to deter­mine if the can­cer has spread beyond the breast and which treat­ments it may respond to. The bal­ance of ben­e­fits ver­sus harms of breast can­cer screen­ing is con­tro­ver­sial. A 2013 Cochrane review stat­ed that it is unclear if mam­mo­graph­ic screen­ing does more good or harm. A 2009 review for the US Pre­ven­tive Ser­vices Task Force found evi­dence of ben­e­fit in those 40 to 70 years of age, and the orga­ni­za­tion rec­om­mends screen­ing every two years in women 50 to 74 years old. The med­ica­tions tamox­ifen or ralox­ifene may be used in an effort to pre­vent breast can­cer in those who are at high risk of devel­op­ing it. Sur­gi­cal removal of both breasts is anoth­er use­ful pre­ven­ta­tive mea­sure in some high risk women. In those who have been diag­nosed with can­cer, a num­ber of treat­ments may be used, includ­ing surgery, radi­a­tion ther­a­py, chemother­a­py, hor­mon­al ther­a­py and tar­get­ed ther­a­py. Types of surgery vary from breast-con­serv­ing surgery to mas­tec­to­my. Breast recon­struc­tion may take place at the time of surgery or at a lat­er date. In those in whom the can­cer has spread to oth­er parts of the body, treat­ments are most­ly aimed at improv­ing qual­i­ty of life and com­fort. Out­comes for breast can­cer vary depend­ing on the can­cer type, extent of dis­ease, and per­son­’s age. Sur­vival rates in the devel­oped world are high, with between 80% and 90% of those in Eng­land and the Unit­ed States alive for at least 5 years. In devel­op­ing coun­tries sur­vival rates are poor­er. World­wide, breast can­cer is the lead­ing type of can­cer in women, account­ing for 25% of all cas­es. In 2012 it result­ed in 1.68 mil­lion cas­es and 522,000 deaths. It is more com­mon in devel­oped coun­tries and is more than 100 times more com­mon in women than in men.