Surgery enhances the effectiveness of peptide receptor radionuclide therapy in metastatic gastroenteropancreatic neuroendocrine tumors.

Background: With the advent of peptide receptor radionuclide therapy, the timing and sequence of surgery in the treatment of metastatic gastroenteropancreatic neuroendocrine tumors merits further study. We hypothesized that surgery before peptide receptor radionuclide therapy might enhance its effectiveness in patients with metastatic gastroenteropancreatic neuroendocrine tumors.

Methods: Eighty-nine patients with metastatic well-differentiated gastroenteropancreatic neuroendocrine tumors treated with ¹⁷⁷Lutetium-dotatate peptide receptor radionuclide therapy between 2018 and 2023 were included. Fifty-six patients underwent surgery (primary tumor resection and/or liver debulking) before peptide receptor radionuclide therapy and 33 patients did not. Primary outcome was progression-free survival according to Response Evaluation Criteria in Solid Tumors. Pretreatment dotatate positron emission tomography/computed tomography was used to calculate tumor volumes.

Results: The surgery and no-surgery groups were well-matched. Median progression-free survival after peptide receptor radionuclide therapy was 15.6 months (interquartile range, 9.1-22.7 months) in the no-surgery group compared with 26.1 months (interquartile range, 12.7-38.1 months) in the surgery group (P = .04). On subgroup analysis, median progression-free survival was 18.1 months (interquartile range, 11.9-38.4 months) in patients who underwent primary tumor resection only compared with 26.2 months (interquartile range, 14.0-38.1 months) in patients who underwent liver debulking (P = .04). Tumor volume was lowest in patients who underwent liver debulking (median 146.07 mL³) compared with no surgery (median 626.42 mL³) (P = .001). On univariable analysis, a tumor volume <138.8 mL³ was associated with longer progression-free survival (hazard ratio, 2.03; 95% confidence interval, 0.95-4.34, P = .05), with a median progression-free survival of 38.1 months (interquartile range, 16.9-41.3 months) compared with 17.8 months (interquartile range, 10.8-28.7 months).

Conclusion: Surgery may enhance the effectiveness of ¹⁷⁷Lutetium-dotatate in the treatment of metastatic well-differentiated gastroenteropancreatic neuroendocrine tumors. This positive effect may be the result of a lower tumor volume in patients after surgery. Our findings fortify the concept of using surgical debulking to improve systemic therapies such as peptide receptor radionuclide therapy.