Authors: Mia Demant, MD, Mia Wagsmo Steffensen, MD
Breast cancer is the most common cancer affecting women and the leading cause of cancer mortality in women worldwide (1). Risk factors include increasing age, reproductive factors (e.g. early menarche, nulliparity, and later onset of menopause all increase the risk of breast cancer), genetic predisposition (e.g. BRCA1 and BRCA2), personal- or family history of breast cancer, and various environmental factors (excessive use of alcohol, obesity and physical inactivity account for 21% of all breast cancer deaths worldwide (2)). Moreover, exogenous hormone exposure (e.g. estrogen treatment in postmenopausal women) increases the risk significantly (3).
It is currently estimated that approximately 25% of all women who undergo mastectomy also have breast reconstruction performed, and 25% of these women are primarily reconstructed, the others are reconstructed secondarily (4).
TNM classification of breast cancer (1)
|Primary tumor (T)|
|TX||Primary tumor cannot be assessed|
|T0||No evidence of primary tumor|
|Tis||Carcinoma in situ|
|Tis (DCIS)||Ductal carcinoma in situ|
|Tis (LCIS)||Lobular carcinoma in situ|
|Tis (Paget’s)||Paget’s disease of the nipple|
|T1||Tumor ≤ 20 mm in greatest dimension|
|T1mi||Tumor ≤ 1 mm in greatest dimension|
|T1a||Tumor > 1 mm but ≤ 5 mm in greatest dimension|
|T1b||Tumor > 5 mm but ≤ 10 mm in greatest dimension|
|T1c||Tumor > 10 mm but ≤ 20 mm in greatest dimension|
|T2||Tumor > 20 mm but ≤ 50 mm in greatest dimension|
|T3||Tumor > 50 mm in greatest dimension|
|T4||Tumor of any size with direct extension to the chest wall and/or to the skin (ulceration or skin nodules)|
|T4a||Extension to the chest wall, not including only pectoralis muscle adherence/invasion|
|T4b||Ulceration and/or ipsilateral satellite nodules and/or edema (including peau d’orange) of the skin, which do not meet the criteria for inflammatory carcinoma|
|T4c||Both T4a and T4b|
|Regional lymph nodes (N)|
|NX||Regional lymph nodes cannot be assessed (for example, previously removed)|
|N0||No regional lymph node metastases|
|N1||Metastases to movable ipsilateral level I, II axillary lymph node(s)|
|N2||Metastases in ipsilateral level I, II axillary lymph nodes that are clinically fixed or matted; or in clinically detected ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases|
|Metastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures|
|N2a||Metastases only in clinically detected ipsilateral internal mammary nodes and in the absence of clinically evident level I, II axillary lymph node metastases|
|N3||Metastases in ipsilateralinfraclavicular (level III axillary) lymph node(s) with or without level I, II axillary lymph node involvement; or in clinically detected ipsilateral internal mammary lymph node(s) with clinically evident level I, II axillary lymph node metastases; or metastases in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement|
|N3a||Metastases in ipsilateralinfraclavicular lymph node(s)|
|N3b||Metastases in ipsilateral internal mammary lymph node(s) and axillary lymph node(s)|
|N3c||Metastases in ipsilateral supraclavicular lymph node(s)|
|Distant metastases (M)|
|M0||No clinical or radiographic evidence of distant metastases|
|cM0(i +)||No clinical or radiographic evidence of distant metastases, but deposits of molecularly or microscopically detected tumor cells in circulating blood, bone marrow, or other nonregional nodal tissue that are no larger than 0.2 mm in a patient without symptoms or signs of metastases|
|M1||Distant detectable metastases as determined by classic clinical and radiographic means and/or histologically proven larger than 0.2 mm|
- Shah R, Rosso K, Nathanson SD. Pathogenesis, prevention, diagnosis and treatment of breast cancer. World J Clin Oncol. 2014 Aug 10;5(3):283–98.
- Danaei G, Vander Hoorn S, Lopez AD, Murray CJL, Ezzati M, Comparative Risk Assessment collaborating group (Cancers). Causes of cancer in the world: comparative risk assessment of nine behavioural and environmental risk factors. Lancet Lond Engl. 2005 Nov 19;366(9499):1784–93.
- Colditz GA, Rosner B. Cumulative risk of breast cancer to age 70 years according to risk factor status: data from the Nurses’ Health Study. Am J Epidemiol. 2000 Nov 15;152(10):950–64.
- Bjarkam CR, Daugaard H, Houlind KC, Hölmich LR, Borgwardt A, Steinmetz J, et al. Kirurgi. FADL; 2020.