Recurrence and treatment trends of pancreatic neuroendocrine tumors

The management of recurrent pancreatic neuroendocrine tumors has changed with improvements in both systemic and locoregional therapies. This study aims to describe the patterns of recurrence and respective treatments and evaluate the changes in multimodality treatment.

This is a single-institution retrospective study of patients diagnosed with a pancreatic neuroendocrine tumor from 2004 to 2022. The primary outcome was time to recurrence. Secondary outcomes included overall survival and therapeutic modality. Time to event probabilities were calculated using the Kaplan-Meier method; probabilities were compared using log-rank tests. Cox proportional hazards multivariable modeling with competing risks yielded subdistribution hazard ratios.

Of 284 patients with a primary pancreatic neuroendocrine tumor, 189 underwent upfront surgical resection and were included in the analysis. Of the 182 patients with a well-differentiated G1 or G2 tumor, 44 patients (24%) experienced a recurrence. Mean time to recurrence was 57 months, with the liver as the most common site (77%, 34/44). On adjusted Cox proportional hazards modeling, only nodal positivity (subdistribution hazard ratio, 4.06; 95% confidence interval, 1.31-12.03, P = .013) was associated with a greater risk of recurrence. There was an increase in adoption of newer liver-directed and systemic therapies in the latter half of the study period, with increased use of therapies such as liver embolization and peptide receptor radionucleotide therapy for recurrences occurring after 2010.

Of the patients with well-differentiated pancreatic neuroendocrine tumors managed with upfront surgical resection, one quarter developed recurrent disease. Nodal positivity was the most significant risk factor for recurrence. The majority of patients received multimodality therapies for recurrent disease.