Grade | Â | Tumor regression |
---|---|---|
Grade 0 | Â | Neither necrosis nor regressive change |
Grade 1 | a | >2/3 vital residual tumor cells |
 | b | Approximately 1/3 to 2/3 vital residual tumor cells |
Grade 2 | Â | <1/3 vital residual tumor cells |
Grade 3 | Â | No vital residual tumor cells |