BreastFor Information Only
when practical. For excisions less than total mastectomy, blocking of tissue includes evaluating the resection margins.
M.TNM and Stage Groupings
The TNM staging system for carcinoma of the breast of the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) is recommended and shown below.21,22 Definitions for classifying the primary tumor (T) are the same for clinical and for pathologic classification. If other measurements, such as mammographic or pathologic, are used, the subsets of T1 can be used.
By AJCC/UICC convention, the designation “T” refers to a primary tumor that has not been previously treated. The symbol “p” refers to the pathologic classification of the TNM, as opposed to the clinical classification, and is based on gross and microscopic examination. pT entails a resection of the primary tumor or biopsy adequate to evaluate the highest pT category, pN entails removal of nodes adequate to validate lymph node metastasis, and pM implies microscopic examination of distant lesions. Clinical classification (cTNM) is usually carried out by the referring physician before treatment during initial evaluation of the patient or when pathologic classification is not possible.
Pathologic staging is usually performed after surgical resection of the primary tumor. Pathologic staging depends on pathologic documentation of the anatomic extent of disease and whether or not the primary tumor has been completely removed. If a biopsied tumor is not resected for any reason (eg, when technically unfeasible) but the highest T and N categories or the M1 category of the tumor can be confirmed microscopically, then the criteria for pathologic classification and staging have been satisfied without total removal of the primary cancer.
Although the pathologist provides information about the individual pTNM categories based on examination of the surgical specimen, the referring physician usually has the responsibility for grouping the TNM categories into a stage of disease.
Primary Tumor (T)
TXPrimary tumor cannot be assessed#
T0No evidence of primary tumor
TisCarcinoma in situ: ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), or Paget disease of the nipple with no tumor##
T1Tumor 2 cm or less in greatest dimension
T1micMicroinvasion 0.1 cm or less in greatest dimension###
T1aTumor more than 0.1 cm but not more than 0.5 cm in greatest dimension
T1bTumor more than 0.5 cm but not more than 1 cm in greatest dimension
T1cTumor more than 1 cm but not more than 2 cm in greatest dimension
T2Tumor more than 2 cm but not more than 5 cm in greatest dimension
T3Tumor more than 5 cm in greatest dimension
T4Tumor of any size with direct extension to chest wall or skin,^ but only as described below
T4aExtension to chest wall, not including pectoralis muscle^^
T4bEdema (including peau d’orange) or ulceration of the skin of the breast or satellite skin nodules confined to the same breast
T4cBoth T4a and T4b