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Breast Cancer Treatment (PDQ®)

  • Updated: 11/14/2014

Table 2. Primary Tumor (T)a,b

TXPrimary tumor cannot be assessed.
T0No evidence of primary tumor.
TisCarcinoma in situ.
Tis (Paget)Paget disease of the nipple NOT associated with invasive carcinoma and/or carcinoma in situ (DCIS and/or LCIS) in the underlying breast parenchyma. Carcinomas in the breast parenchyma associated with Paget disease are categorized based on the size and characteristics of the parenchymal disease, although the presence of Paget disease should still be noted.
T1Tumor ≤20 mm in greatest dimension.
T1miTumor ≤1 mm in greatest dimension.
T1aTumor >1 mm but ≤5 mm in greatest dimension.
T1bTumor >5 mm but ≤10 mm in greatest dimension.
T1cTumor >10 mm but ≤20 mm in greatest dimension.
T2Tumor >20 mm but ≤50 mm in greatest dimension.
T3Tumor >50 mm in greatest dimension.
T4Tumor of any size with direct extension to the chest wall and/or to the skin (ulceration or skin nodules).c
T4aExtension to the chest wall, not including only pectoralis muscle adherence/invasion.
T4bUlceration and/or ipsilateral satellite nodules and/or edema (including peau d'orange) of the skin, which do not meet the criteria for inflammatory carcinoma.
T4cBoth T4a and T4b.
T4dInflammatory carcinoma.

DCIS = ductal carcinoma in situ; LCIS = lobular carcinoma in situ.
*Information about LCIS is not included in this summary.
aReprinted with permission from AJCC: Breast. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 347-76.
bThe T classification of the primary tumor is the same regardless of whether it is based on clinical or pathologic criteria, or both. Size should be measured to the nearest millimeter. If the tumor size is slightly less than or greater than a cutoff for a given T classification, it is recommended that the size be rounded to the millimeter reading that is closest to the cutoff. For example, a reported size of 1.1 mm is reported as 1 mm, or a size of 2.01 cm is reported as 2.0 cm. Designation should be made with the subscript "c" or "p" modifier to indicate whether the T classification was determined by clinical (physical examination or radiologic) or pathologic measurements, respectively. In general, pathologic determination should take precedence over clinical determination of T size.
cInvasion of the dermis alone does not qualify as T4.