| Simplified AJCC TNM classification 2017 | |
| Categories | Criteria |
| Tumor |
|
| TX | Primary tumor cannot be assessed |
| T0 | No evidence of primary tumor |
| Tis | Ductal carcinoma |
| T1 | Tumor ≤ 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) |
| T4a | Extension to the chest wall |