# Neuroendocrine tumour grade (Ki-67) and WHO classification

Source: https://onco.cc/terms/net-grade-ki67/  
OnCo record `net-grade-ki67` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

How fast the tumour cells are dividing, measured by Ki-67 staining, separates slow-growing neuroendocrine tumours from aggressive neuroendocrine carcinomas and decides the treatment.

## Summary

WHO 2019/2022: well-differentiated NET grade 1 (Ki-67 <3%), grade 2 (3-20%), grade 3 (>20%, well-differentiated); poorly differentiated neuroendocrine carcinoma (NEC, small- or large-cell) is a separate lineage treated like small-cell lung cancer. Grade drives choice among somatostatin analogues, PRRT, targeted therapy and chemotherapy.

## Fields

- Kind: Term
- Last checked: 2026-09-07

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Neuroendocrine_tumor
- Wikipedia: https://en.wikipedia.org/wiki/Neuroendocrine_tumor

## Connected records

- cancers: [Extrapulmonary neuroendocrine carcinoma](https://onco.cc/cancers/extrapulmonary-nec/), [Grade 3 well-differentiated neuroendocrine tumour](https://onco.cc/cancers/grade-3-net/), [Lung neuroendocrine tumours (typical and atypical carcinoid)](https://onco.cc/cancers/lung-net/), [Neuroendocrine tumours](https://onco.cc/cancers/neuroendocrine/), [Pancreatic neuroendocrine tumours](https://onco.cc/cancers/pancreatic-net/), [Small intestinal neuroendocrine tumours](https://onco.cc/cancers/small-intestinal-net/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/)
- technologies: [Histopathology & immunohistochemistry](https://onco.cc/technologies/histopathology-ihc/)
- people: [Steve Jobs](https://onco.cc/people/steve-jobs/)
- targets: [Ki-67 (MKI67)](https://onco.cc/targets/mki67/)
- biomarkers: [Ki-67 index (proliferation by IHC)](https://onco.cc/biomarkers/ki-67-index/), [Somatostatin receptor expression by PET (SSTR-positive)](https://onco.cc/biomarkers/sstr-pet-expression/)

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