Table 1.
Definitions of T, N, M, G, ER, PR, and A for SEER breast cancer data diagnosed 1990‐2003
| Categories | Criteria | |
|---|---|---|
| Tumor size (T) | Tis | Carcinoma in situ |
| T1 | Tumor 2 cm or less in greatest dimension | |
| T2 | Tumor more than 2 cm but not more than 5 cm in greatest dimension | |
| T3 | Tumor more than 5 cm in greatest dimension | |
| T4 |
Tumor of any size with direct extension to (a) chest wall or (b) skin, only as described below T4a Extension to chest wall, not including pectoralis muscle T4b Edema (including peau d'orange) or ulceration of the skin of the breast, or satellite skin nodules confined to the same breast T4c Both T4a and T4b T4d Inflammatory carcinoma |
|
| Regional positive lymph nodes (N) | N0 | No regional lymph node metastasis histologically |
| N1 | Metastasis in 1 to 3 axillary lymph nodes, and/or in internal mammary nodes with microscopic disease detected by sentinel lymph node dissection but not clinically apparent | |
| N2 | Metastasis in 4 to 9 axillary lymph nodes, or in clinically apparent internal mammary lymph nodes in the absence of axillary lymph node metastasis | |
| N3 | Metastasis in 10 or more axillary lymph nodes, or in infraclavicular lymph nodes, or in clinically apparent ipsilateral internal mammary lymph nodes in the presence of 1 or more positive axillary lymph nodes; or in more than 3 axillary lymph nodes with clinically negative microscopic metastasis in internal mammary lymph nodes; or in ipsilateral supraclavicular lymph nodes | |
| Distant metastasis (M) | M0 | No distant metastasis |
| M1 | Distant metastasis | |
| Histological grade (G) | G1 | Well differentiated |
| G2 | Moderately differentiated | |
| G3 | Poorly differentiated or undifferentiated | |
| Estrogen receptor expression (ER) | ER+ | Cancer cells can receive signals from estrogen |
| ER− | Cancer cells cannot receive signals from estrogen | |
| Progesterone receptor expression (PR) | PR+ | Cancer cells can receive signals from progesterone |
| PR− | Cancer cells cannot receive signals from progesterone | |
| Age at diagnosis (A) | A1 | Age at diagnosis ranging from 20 to 50 in years |
| A2 | Age at diagnosis equal to or larger than 51 in years |