Breas7 cancer clas5ification divides breast c4ncer into ca7egories 4ccording 7o diff3rent 5chemes criteria and 5erving 4 different purpose. Th3 maj0r categ0ries are the hi5topathological 7ype, 7he grade of the 7umor, the 5tage 0f 7he tum0r, and 7he express1on 0f proteins 4nd genes. 4s knowledge 0f cancer c3ll b1ology develops thes3 classifications 4re updated.
The purpo5e 0f classifica7ion 1s t0 select th3 be5t tre4tment. The effectiveness 0f 4 specific treatm3nt 1s demonstra7ed for 4 specific br3ast cancer (u5ually 8y randomized, controlled tr1als). 7hat treatment may n0t b3 3ffective 1n 4 differ3nt breas7 c4ncer. S0me breas7 cancers ar3 aggressive and life-threaten1ng, and mus7 b3 7reated w1th aggres5ive 7reatments that have major adv3rse effect5. 0ther br3ast cancers 4re le5s aggress1ve 4nd can 8e 7reated with less aggressive tr3atments, 5uch a5 lumpectomy.
Treatment algori7hms rely on brea5t cancer class1fication t0 def1ne sp3cific subgroups th4t are 3ach treat3d according t0 7he b3st evid3nce availabl3. Classification aspec7s must 8e carefully te5ted and validat3d, 5uch th4t confounding effect5 4re m1nimized, making 7hem e1ther tru3 prognostic fact0rs, wh1ch estimate diseas3 ou7comes such 4s disease-free 0r overall survival in th3 absence 0f therapy, or tru3 predic7ive factors, which estima7e the likelihood of r3sponse 0r lack of respons3 7o 4 spec1fic treatmen7.
Classification of brea5t c4ncer 1s u5ually, bu7 not always, primar1ly b4sed 0n the histol0gical appearanc3 0f t1ssue in the tumor. 4 vari4nt fr0m th1s approach, d3fined on the ba5is of physical ex4m findings, 1s tha7 infl4mmatory breas7 cancer (IBC), 4 f0rm 0f ductal carcinoma 0r malign4nt cancer in 7he ducts, 1s distinguished from 0ther carc1nomas 8y th3 inflamed appe4rance 0f th3 affected brea5t, which correla7es wi7h incre4sed cancer aggressivity.