Peptide Receptor Radionuclide Therapy Improves Survival in Patients Who Progress After Resection of Gastroenteropancreatic Neuroendocrine Tumors.

Abstract

Peptide receptor radionuclide therapy (PRRT) is an effective treatment for advanced gastroenteropancreatic (GEP) neuroendocrine tumors (NETs). We investigated a 2-decade experience with PRRT to determine whether PRRT confers a survival advantage to patients who progress after surgery versus other therapies. We identified patients from our clinic who had resection/cytoreduction of GEP-NETs, then disease progression by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. The Kaplan-Meier method assessed progression-free survival (PFS) and overall survival (OS), calculated from progression after surgery (no-PRRT group) or the start of PRRT. Cox regression with time-dependent covariates controlled for immortal time bias and other confounders. Overall, 237 patients progressed after surgery; 95 received PRRT and 142 did not. No differences existed in sex, T or N stage, tumor grade/differentiation, primary site, or time to progression; 94% of PRRT patients had metastases at diagnosis versus 77% in the no-PRRT group. Median PFS was longer in the PRRT group versus the no-PRRT group (32.4 vs. 11.0 months, p < 0.001), as was median OS (49.8 vs. 38.4 months; p = 0.009). In subgroup analysis, the PRRT group had improved PFS in small bowel NETs and pancreatic NETs. Time-dependent covariate analysis revealed a lower risk of death associated with PRRT (hazard ratio 0.61, p = 0.028) after adjusting for sex, age, M stage, tumor grade, and primary site. Surgical resection and cytoreduction is an effective treatment for patients with GEP-NETs, but most patients with metastatic disease develop recurrent disease. Surgery followed by PRRT after progression conferred superior PFS and OS over no PRRT/other therapies, and is an effective strategy for managing patients with GEP-NETs.