Table 1.
Clinical stages of feline tumors of epidermal origin
| Site | Stage | Definition |
|---|---|---|
| Primary tumor | Tis | Preinvasive carcinoma (carcinoma in situ) |
| T0 | No evidence of tumor | |
| T1 | Tumor <2 cm in maximal diameter, superficial or exophytic | |
| T2 | Tumor 2–5 cm in maximal diameter or minimal invasion regardless of size | |
| T3 | Tumor >5 cm in maximal diameter or with invasion of the subcutis, irrespective of size | |
| T4 | Tumor invades deeper structures (fascia, muscle, bone, or cartilage) | |
| Regional lymph nodes | N0 | No evidence of regional lymph node involvement |
| Distant metastasis | M0 | No evidence of distant metastasis |
Data from Owen L. TNM classification of tumors in domestic animals. Geneva: World Health Organization; 1980.