MKI67 and neoplasm: Tumor grade is defined numerically, as follows: low‐grade (grade 1 [G1]) tumors have a mitotic rate from 0 to 1 per 10 high‐power fields (HPFs) or a Ki‐67 index from 0% to 2%; intermediate‐grade (G2) tumors have a mitotic rate from 2 to 20 per 10 HPFs or a Ki‐67 index from 3% to 20%; and high‐grade (G3) tumors have a mitotic rate >20 per 10 HPFs or a Ki‐67 index >20%.11