MKI67 and neuroendocrine carcinoma: Ki67 is a protein encoded by the MKI67 gene, and its expression in the nucleus is cell‐cycle dependent and is involved in the whole phase from G1 to M.3, 4, 5Notably, as the most classical biomarker used in assessing active tumour proliferation, Ki67 has been routinely applied for the immunohistochemical evaluation of malignancy and prognostic judgement in breast and neuroendocrine cancers.