| TX | Primary tumor cannot be assessed |
| T0 | No evidence of primary tumor |
| Tis | Carcinoma in situ: intraepithelial tumor without invasion of the lamina propria, high-grade dysplasia |
| T1 | Tumor invades lamina propria, muscularis mucosa or submucosa |
| T1a | Tumor invades lamina propria or muscularis mucosa |
| T1b | Tumor invades the submucosa |
| T2 | Tumor invades the muscularis propria |
| T3 | Tumor penetrates the subserosal connective tissue |
| T4 | Tumor invades the serosa or adjacent structures |
| T4a | Tumor invades the serosa |
| T4b | Tumor invades adjacent structures/organs |