Table 1. Primary Tumor (T)a
| TX | Primary tumor cannot be assessed. |
| T0 | No evidence of primary tumor. |
| Tis | Carcinoma in situ (i.e., Bowen disease, high-grade squamous intraepithelial lesion, and anal intraepithelial neoplasia II–III.) |
| T1 | Tumor ≤2 cm in greatest dimension. |
| T2 | Tumor >2 cm but ≤5 cm in greatest dimension. |
| T3 | Tumor >5 cm in greatest dimension. |
| T4 | Tumor of any size invades adjacent organ(s), e.g., vagina, urethra, and bladder.b |
| aReprinted with permission from AJCC: Anus. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 165-73. |
| bDirect invasion of the rectal wall, perirectal skin, subcutaneous tissue, or the sphincter muscle(s) is not classified as T4. |
