Breast cancer stages and their importance

The stages of breast cancer are determined according to the TNM classification (American Joint Committee, 1992), in which breast cancer is staged according to the size of the primary tumor (T), the involvement of the corresponding axillary lymph nodes (N) and the presence or absence of metastases (M). Proper staging of breast cancer is extremely important.
Not only does it allow for accurate prognosis but also, in many cases, treatment decision is largely based on TNM classification (Table 2).

Breast cancer stages according to ΤΝΜ

There are four stages of breast cancer.

Stage 0
Stage 0 is the in situ cancer that is located at its source and has not begun to infiltrate the surrounding tissues or spread and includes in situ lobular carcinomas and in situ carcinomas of the mammary ducts.

Stage I
In Stage I (T1NOMO) the tumor is 2cm in size or smaller and there is no evidence of spread to the lymph nodes or in remote areas.

Stage II A
Stage II A includes the categories TON1M0, where there is no indication of primary tumor but metastasis to the axillary lymph nodes, T2N0M0, with a tumor greater than 2cm but not larger than 5cm and without dispersion in the lymph nodes.

Stage ΙΙ Β
Stage II B includes the categories T2N1M0, with a tumor of 2-5cm and with positive lymph nodes and T3N0M0, with a tumor greater than 5cm without lymph node metastases.

Stage III A
Stage III A, then, consists of the categories T0N2M0, T1N2M0, T2N2M0, T3N1M0 and T3N2M0, in which the tumour is larger than 5cm and there is involvement of the corresponding axillary lymph nodes that are fused with each other or with other tissues.

Stage III B
Stage III B includes T4 anyN M0 and anyT N3 M0, where there are affected thoracic lymph nodes and the tumour extends into the chest wall or invades and progresses to the skin.

Stage IV
Finally, Stage IV includes categories with any size of tumour, with spread to the lymph nodes, but also with distant metastases or involvement of the skin and chest wall beyond the breast area.

Πηγή: American Joint Committee, «Σταδιοποίηση του καρκίνου του μαστού», Πάνω απ΄ όλα Γυναίκα, Οδηγός για τον Καρκίνο του Μαστού, Εκδόσεις Διόπτρα.