MKI67 and neuroendocrine carcinoma: Indeed, the relevance of Ki67 LI in NENs has long been reflected in the GEP-NENs classification system, and is also known to be prognostic in the Nordic NEC study, in which a poorer RR to platinum-based chemotherapy in patients with a Ki67 LI <55% compared to patients with a Ki67 LI ≥55% was observed [26].