A relook at gastroenteropancreatic neuroendocrine tumours as per 2019 WHO classification-A tertiary centre experience

Neuroendocrine neoplasm of GIT (gastrointestinal tract) and pancreas is heterogenous with variable clinical features and disease outcomes. Despite multiple attempts of risk stratification by grading and staging, some have unpredictable clinical courses. Well-differentiated grade 3 neuroendocrine tumour (G3NET) is a recent subcategory introduced in the 2019 WHO classification based on morphology, molecular profile and prognosis distinguishing it from neuroendocrine carcinoma(NEC). This study aimed at describing the spectrum of NENs encountered in a tertiary centre with focus on reclassifying previously reported G3 tumours into G3 NET and NEC and comparing the survival between them.

This is an 8-year retrospective study of all gastro-entero-pancreatic neuroendocrine neoplasms reclassified according to the 2019 WHO classification based on morphology and Ki-67 index with analysis of the survival rates between the categories. Minimum follow-up period was 20 months.

Eighty-six patients with NENs of gastro-entero-pancreas were included, with median age group of 40-60 years (age range 9 to 79 years) and male:female ratio of 1.7:1. The tumour grade correlated with the TNM staging and most of the syndromic NETs were low grade. Eleven percent of the tumours were reclassified as well-differentiated G3NETs. The survival of G3 NETs was higher than NEC.

Grading of NEN is vital for therapeutic decisions and for prognostication. Currently, morphology is the key to recognise the well-differentiated G3 NETs, but can be subject to interobserver variability. Molecular surrogates may play a role in accurately identifying these entities, the validity of which is warranted.