A summary of the commonly used systems for assessing rectal tumour regression
| Dworak et al 22 | |
| GR 0 | No regression |
| GR 1 | Dominant tumour mass with obvious fibrosis and/or vasculopathy |
| GR 2 | Dominant fibrotic changes with few tumour cells or groups (easy to find) |
| GR 3 | Very few (difficult to find microscopically) tumour cells in fibrotic tissue with or without mucous substance |
| GR 4 | No tumour cells, only fibrotic mass |
| Rectal Cancer Regression Grading (RCRG) system | |
| RCRG 1 | Sterilisation or only microscopic foci of adenocarcinoma remaining, with marked fibrosis |
| RCRG 2 | Marked fibrosis but macroscopic disease present |
| RCRG 3 | Little or no fibrosis, with abundant macroscopic disease |
| RCPath dataset for colorectal cancer | |
| RCPath A | No residual tumour cells and/or mucus lakes only |
| RCPath B | Minimal residual tumour, that is, only occasional microscopic foci are identified with difficulty |
| RCPath C | No marked regression |
GR, grading of regression; RCPath, Royal College of Pathologists.