MED-NERD
Staging of Breast Cancer (TNM system)
Staging of breast cancer is based on the site, the size, and the spread of the primary tumour to lymph nodes or distant areas of the body. It also includes the tumour grade and the presence of some biomarkers. Grading system describes the growth and spread of breast tumour. Biomarkers are used to detect certain receptors of breast tumour.
This is done through using TNM system as the following:
-Tumour (T): Indicates the size and site of the tumour.
-Lymph Node (N): Indicates the size and site of lymph nodes affected by cancer spread.
-Metastasis (M): Indicates the spread of cancer to nearby or distant areas of the body.
(1) Tumour (T): indicates the size and site of the tumour.
-TX: Primary tumour cannot be assessed.
-T0: No sign found of the primary tumour.
-Tis: Carcinoma in situ.
Carcinoma in situ include two types:
1-Ductal carcinoma in situ (DCIS): abnormal cells are found in the lining of the ducts of the breast and without spread to other breast tissues, but it may become invasive and may spread to other tissues of the breast.
2-Paget disease of the nipple: abnormal cells are found in the nipple skin cells and may spread to the areola. This type of cancer is not staged according to the TNM system.
-T1: The size of the tumour is 20 mm or less.
According to the size of the tumour, this stage includes 4 subtypes:
1-T1mi: The size of the tumour is 1 mm or less.
2- T1a: The size of the tumour is more than 1 mm but less than 5 mm.
3-T1b: The size of the tumour is more than 5 mm but less than 10 mm.
4-T1c: The size of the tumour is more than 10 mm but less than 20 mm.
-T2: The size of the tumour is more than 20 mm but less than 50 mm.
-T3: The size of the tumour is more than 50 mm.
-T4: includes the following:
1-T4a: The tumor reached the chest wall.
2-T4b: The growth of the tumor reached the skin forming an ulcer on the skin surface with formation of small tumor nodules and association of swelling of the breast in the same breast.
3-T4c: The tumor growth reached the chest wall and the skin.
4-T4d: This stage represents inflammatory breast cancer with redness and swelling involving one third or more of the breast skin which is known as (peau d’orange).
See: Full article about breast cancer
(2) Lymph Node (N): indicates the size and site of lymph nodes affected by cancer spread. Microscopic examination of lymph nodes after surgical removal is described as the following:
-NX: Lymph nodes cannot be assessed.
-N0: No cancer found in lymph nodes, or small cancer cells less than 0.2 mm found in lymph nodes.
-N1: This stage involves the following:
1-N1mi: Cancer spread to axillary lymph nodes and is more than 0.2 mm in size but less than 2 mm.
2-N1a: Cancer spread to 1-3 axillary lymph nodes and the size of cancer in at least one lymph node is more than 2 mm.
3-N1b: Cancer size is more than 0.2 mm found by sentinel lymph node biopsy, not found in spread to axillary lymph nodes, and spread to lymph nodes near the breastbone on the same side of the primary tumor.
4- N1c: Cancer spread to 1-3 axillary lymph nodes the size of cancer in at least one lymph node is more than 2 mm, found by sentinel lymph node biopsy, and spread to lymph nodes near the breastbone on the same side of the primary tumor.
-N2: This stage is described as the following:
1-N2a: Cancer spread to 4-9 axillary lymph nodes, the size of cancer in at least one lymph node is more than 2 mm.
2-N2b: Cancer spread to lymph nodes near the breastbone, found by imaging tests, not found in the axillary lymph nodes whether by lymph node dissection or sentinel lymph node biopsy.
-N3: This stage describes the tumour as the following:
1- N3a: Cancer spread to 10 or more more axillary lymph nodes, the size of cancer in at least one of these lymph nodes is more than 2 mm, or cancer spread to sub-clavicular lymph nodes.
2- N3b:
*Cancer spread to 1-9 axillary lymph nodes, the size of cancer in at least one of these lymph nodes is more than 2 mm, found by imaging studies, and has spread to lymph nodes near the breastbone.
*Cancer spread to 4-9 axillary lymph nodes, the size of cancer in at least one of these lymph nodes is more than 2 mm, has spread to lymph nodes near the breastbone on the same side, and tumor size more than 0.2 mm is found by sentinel lymph node biopsy.
3- N3c: Cancer spread to supra-clavicular lymph nodes on the same side of the primary lesion.
(3) Metastasis (M): indicates the spread of cancer to nearby or distant areas of the body. This is describes as the following:
-M0: No sign of cancer spread to other areas of the body.
-M1 (Metastatic breast cancer): Cancer spread to other areas of the body mainly lung, liver, bone, and the brain. The size of cancer if it has spread to distant lymph nodes is more than 0.2 mm.
See: Full article about breast cancer
See: Gestational Trophoblastic Neoplasia (GTN): Choriocarcinoma
References:
(1) Breast cancer, national cancer institute (NIH).
https://www.cancer.gov/types/breast/hp/breast-treatment-pdq
(2) Breast cancer, National breast cancer foundation.
https://www.nationalbreastcancer.org/about-breast-cancer/
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