Outcomes of peptide receptor radionuclide therapy after progression following hepatic cytoreductive operation for neuroendocrine tumors.

BACKGROUND

Peptide receptor radionuclide therapy (PRRT) attaches radioactive lutetium-177 to octreotide to treat inoperable metastatic gastroenteropancreatic neuroendocrine tumors (GEPNETs). PRRT has been available in Europe for decades, receiving FDA approval in 2018 after the NETTER-1 trial, which showed improved progression free survival (PFS), but not overall survival (OS). However, Borbon et al. recently showed an OS of 156 months in patients receiving PRRT for progression after hepatic cytoreduction operations (HCO) compared to 106 months for other treatments, implying PRRT is superior. This finding needs confirmation from another major GEPNET center.

METHODS

Our database was reviewed for patients who received PRRT for inoperable progression following HCO. Data collected included primary tumor type, grade, date of operation, date of inoperable progression, date of progression after PRRT, and status at last follow up. PFS and OS were calculated using Kaplan and Meier analyses and compared between subgroups.

RESULTS

Seventy-five patients were identified. There were 52 patients with small bowel and 23 with pancreatic primaries. Median PFS after cytoreduction was 44 months. Median PFS after PRRT was 32 months. Median OS was 97 months. There weren't significant differences in PFS or OS based on primary type or grade. On multivariate Cox regression, neither primary site nor PRRT timing independently predicted OS.

CONCLUSIONS

Our results do not confirm those of Borbon et al. Our survival after PRRT was closer to what they found with other therapies. We conclude that PRRT is a treatment option for patients with inoperable progression after HCO, but not necessarily superior.