Breast cancer is one of the most common types of cancer among women. It takes the 1st place (in Russia more than 55,000 women are diagnosed with breast cancer each year). In addition, the morbidity is increasing. Breast cancer – is the most common cause of death among women aged from 35 to 54 years.
The TNM system
First of all, the TNM classification is based primarily on clinical definition, when it is possible – on histo pathological, anatomical definition of the spread of the disease.
It is extremely important to determine the prognosis and to plan the most effective course of treatment, which requires an objective assessment of the anatomical spread of the lesion. For this purpose, you need to have the classification, the basic principles which would be applied to all localizations of malignant tumors, regardless of the planned treatment. The TNM system fully meets all these requirements.
Breast cancer staging
Breast tumors are staged by the following criteria:
- Evaluation categories: «T» (tumor), «N» (lymph node), «M» (distant metastasis).
- Histopathologic differentiation «G» (describes the histological characteristics of the tumor).
- Classification «R» (describes the state of the residual tumor).
- Staging classification (tumor staging at I, II, III /, stage IV).
Stage 1. The tumor size does not exceed 2 cm. The lymph glands in the armpit are not exposed and there is no indicator that the cancer has spread to other parts of the body.
Stage 2. The tumor size is from 2 to 5 cm, or the lymph glands in the armpit are affected, or both. However, there is no indicator that the cancer has spread further.
Stage 3. The tumor size is greater than 5 cm, and it affects the surrounding structures, such as skin or muscle. The lymph glands in the armpit are usually affected, but there are no indicators that the cancer has spread further than the breast or underarm lymph glands.
Stage 4. The tumor is of any size, but the lymph glands are usually affected and the cancer has spread to other parts of the body. This is a secondary or metastatic cancer. Breast cancer that has emerged again after the initial treatment is called recurrent breast cancer.
The TNM classification for staging of breast cancer
Another staging system known as the TNM system, is used everywhere. It may give more precise information on the extent of cancer.
T describes the size of the tumor.
N describes whether the cancer has spread to the lymph nodes.
M describes whether the cancer has spread to another part of the body, such as bone, liver or lungs.
T – Primary tumor
- TX – primary tumor can not be assessed.
- T0 – primary tumor is not determined.
- Tis – preinvasive carcinoma (in situ).
- Tis (DCIS) – ductal carcinoma.
- Tis (LCIS) – lobular carcinoma.
- Tis (Paget) – Paget’s disease of the nipple without the presence of the tumor.
- T1 – tumor is up to 2 cm in greatest dimension.
- T1mic (mikroinvaziya) – up to 0.1 cm in greatest dimension.
- T1a – 0.5 cm in greatest dimension.
- T1b – up to 1 cm in greatest dimension.
- T1c – up to 2 cm in greatest dimension.
- T2 – tumor is up to 5 cm in greatest dimension.
- T3 – tumor is more than 5 cm in greatest dimension.
- T4 – tumor with a direct extension to the skin or chest wall, the tumor of any size.
- T4a – tumor spreads to the chest wall.
- T4b – edema (including “lemon peel”), or ulceration of the skin of the breast or metastases in the skin of the breast.
- T4c – signs of the first two.
- 4d – inflammatory forms of cancer.
N – Regional lymph nodes
- Nx – insufficient amount of data needed to evaluate the state of the regional lymph nodes.
- N0 – the signs of metastatic regional lymph nodes are absent.
- N1 – metastases in the axillary lymph biased site (s) on the affected side.
- N2 – metastases in the axillary lymph nodes, fixed to each other or clinically defined metastases in the lymph chest nodes on the affected side, with the absence of metastases in the axillary lymph nodes.
- N2a – metastases in the axillary lymph nodes fixed to other structures, or to each other.
- N2b – metastasis, which is determined clinically in the internal mammary lymph nodes with the absence of clinically detectable metastases in the axillary lymph nodes.
- N3 – metastases in the subclavian lymph nodes with or without metastases in the axillary lymph nodes or clinically determined metastases in the internal lymph nodes of the breast, on the affected side with the presence of metastases in the lymph nodes of the armpit – or metastasis in the supraclavicular lymph nodes on the affected side with / without metastases in the axillary lymph nodes or in the internal breast lymph nodes.
- N3a – subclavian lymph node metastases.
- N3b – metastases on the affected side in the internal mammary lymph nodes.
- N3c – Metastasis in the supraclavicular lymph nodes.
M – Distant metastases
- MX – insufficient amount of data required for the definition of distant metastases.
- MO –the signs of metastases are absent.
- M1 – there are distant metastases.
It should be noted that the categories M1 and pM1 can be supplemented as a result of the localization of some metastases: Easy PUL, Brain BRA, Bones OSS, liver HEP, Bone marrow MAR, Lymph nodes LYM, Pleura PLE, adrenal glands ADR, Skin SKI, Peritoneum PER and Other OTH.
The presence or absence of the residual tumor after treatment is determined by the R.
- Rx – insufficient amount of data necessary for the definition of the residual tumor.
- R0 – no residual tumor.
- R1 – microscopically determined residual tumor.
- R2 – residual tumor is determined by the naked eye.