From: Breast Cancer Treatment (Adult) (PDQ®)
PDQ Cancer Information Summaries [Internet].
Bethesda (MD): National Cancer Institute (US); 2002-.
NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Table 2. Definition of Primary Tumor (T) – Clinical and Pathologicala
| T Category | T Criteria |
|---|---|
| TX | Primary tumor cannot be assessed. |
| T0 | No evidence of primary tumor. |
| Tisb | DCIS. |
| Tis (Paget) | Paget disease of the nipple NOT associated with invasive carcinoma and/or DCIS 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. |
| T1 | Tumor ≤20 mm in greatest dimension. |
| –T1mi | Tumor ≤1 mm in greatest dimension. |
| –T1a | Tumor >1 mm but ≤5 mm in greatest dimension (round any measurement >1.0–1.9 mm to 2 mm). |
| –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 macroscopic nodules); invasion of the dermis alone does not qualify as T4. |
| –T4a | Extension to the chest wall; invasion or adherence to pectoralis muscle in the absence of invasion of chest wall structures does not qualify as T4. |
| –T4b | Ulceration and/or ipsilateral macroscopic satellite nodules and/or edema (including peau d'orange) of the skin that does not meet the criteria for inflammatory carcinoma. |
| –T4c | Both T4a and T4b are present. |
| –T4d | Inflammatory carcinoma (see Rules for Classificationc). |
DCIS = ductal carcinoma in situ.
aReprinted with permission from AJCC: Breast, revised version. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp. 4–96.
bLobular carcinoma in situ is a benign entity and is removed from TNM staging in the AJCC Cancer Staging Manual, 8th ed.
cRules for Classification - The anatomic TNM system is a method for coding extent of disease. This is done by assigning a category of extent of disease for the tumor (T), regional lymph nodes (N), and distant metastases (M). T, N, and M are assigned by clinical means and by adding surgical findings and pathological information to the clinical information. The documented prognostic impact of postneoadjuvant extent of disease and response to therapy warrant clear definitions of the use of the yp prefix and response to therapy. The use of neoadjuvant therapy does not change the clinical (pretreatment) stage. As per TNM rules, the anatomic component of clinical stage is identified with the prefix c (e.g., cT). In addition, clinical staging can include the use of fine-needle aspiration (FNA) or core-needle biopsy and sentinel lymph node biopsy before neoadjuvant therapy. These are denoted with the postscripts f and sn, respectively. Nodal metastases confirmed by FNA or core-needle biopsy are classified as macrometastases (cN1), regardless of the size of the tumor focus in the final pathological specimen. For example, if, prior to neoadjuvant systemic therapy, a patient with a 1 cm primary has no palpable nodes but has an ultrasound-guided FNA biopsy of an axillary lymph node that is positive, the patient will be categorized as cN1 (f) for clinical (pretreatment) staging and is assigned to Stage IIA. Likewise, if the patient has a positive axillary sentinel node identified before neoadjuvant systemic therapy, the tumor is categorized as cN1 (sn) (Stage IIA). As per TNM rules, in the absence of pathological T evaluation (removal of the primary tumor), which is identified with prefix p (e.g., pT), microscopic evaluation of nodes before neoadjuvant therapy, even by complete removal such as sentinel node biopsy, is still classified as clinical (cN).