Pancreatic neuroendocrine tumours: Grade is superior to T, N, or M status in predicting outcome and selecting patients for chemotherapy:A retrospective cohort study in the SEER database

Pancreatic neuroendocrine tumours (pNETs) are a rare and heterogeneous group of tumours with an increasing incidence. Current staging criteria for pNETs remain limited and controversial. Meanwhile, the impact of chemotherapy on overall survival has not been fully defined. The current study aimed to explore epidemiologic trends of pancreatic neuroendocrine tumours (pNETs). To determine feasible improvements to staging criteria and investigate the relationship between chemotherapy and survival. A retrospective cohort study design was used to analyse annual cancer incidence rates, patient demographics, tumour site and stage, and treatment of pNETs. Data were obtained from the National Cancer Institute's SEER registry for all patients diagnosed with pNETs between January 1973 and December 2015. Patients diagnosed after 2010 were more likely to present with age greater than 45 years, T0, T1 status, N0 status, M0 status, and well differentiation. Current AJCC staging criteria was applicable to patients with well differentiation, but not other differentiation. The revised system, defined by Grade, T, N, and M status, could robustly discriminate between survival curves. Chemotherapy was associated with significantly improved survival for patients with poorly differentiated and undifferentiated tumour grading. Grade is superior to ‘T’, ‘N’, or ‘M’ status in predicting outcomes and selecting patients for chemotherapy. It is necessary and feasible to combine grade into current staging criteria. • There has been a steady increase in the incidence of pNETs, coincident with the migration to earlier disease stage. • Grade is superior to ‘T’, ‘N’, or ‘M’ status in predicting outcomes and selecting patients for chemotherapy. • We proposed a modified staging classification defined by Grade, as well as T, N, and M status.