MKI67 and neuroendocrine neoplasm: Besides, the WHO grade (G grade) of neuroendocrine neoplasms (NENs) was reclassified as NET‐G1, NET‐G2, NET‐G3, and NEC (grouped into G4 in the article), based on Ki‐67 index, mitotic rate and differentiation,5 but is not widely clinically used.