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Residual tumor (R) classification.
| Classification | Description |
|---|---|
| R0 | The entire tumor is destroyed in response to treatment |
| R1 | More than 70% of the tumor is destroyed in response to treatment, and fibrosis and diffuse apoptosis (within the tumor) are observed |
| R2 | 30 and 70% of tumors in response to treatment have undergone fibrosis and apoptosis |
| R3 | The response rate to treatment is very low or non-existent |
