To Perform, or Not to Perform Interim PET: Questioning the Impact of Midtherapy Evaluation During PRRT in GEP-NET Patients

Christoph Wetz; Tristan Ruhwedel; Julian M M Rogasch; Peter R Steinhagen; Felix Bolduan; Holger Amthauer; Imke Schatka

doi:10.1097/RLU.0000000000005479

To Perform, or Not to Perform Interim PET: Questioning the Impact of Midtherapy Evaluation During PRRT in GEP-NET Patients

Clin Nucl Med. 2024 Oct 10. doi: 10.1097/RLU.0000000000005479. Online ahead of print.

Authors

Christoph Wetz¹, Tristan Ruhwedel¹, Julian M M Rogasch, Peter R Steinhagen², Felix Bolduan, Holger Amthauer¹, Imke Schatka¹

Affiliations

¹ From the Department of Nuclear Medicine, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.
² Department of Hepatology and Gastroenterology, Charité-Universitätsmedizin Berlin, Campus Virchow Clinic, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany.

PMID: 39388313
DOI: 10.1097/RLU.0000000000005479

Abstract

Purpose: This study aimed to analyze the impact of interim evaluation on the continuation of 177Lu-based peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and to survey its usage across German university hospitals.

Patients and methods: In 119 GEP-NET patients who underwent PRRT, we retrospectively assessed the results and therapeutic impact of restaging performed after 2 cycles using MRI/CT/somatostatin receptor imaging. Therapeutic decisions based on interim PET results were made in multidisciplinary tumor board meetings. Additionally, an online survey was conducted among 37 German university hospitals regarding their interim evaluation practices, focusing on the change in management.

Results: Of 119 patients, 83 completed 4 PRRT cycles; 36 stopped after 2: 27 showed PD, 3 had PR leading to surgery, 5 experienced toxicity, and 1 died. Those completing 4 cycles showed a median PFS of 38.0 months (95% confidence interval, 32.2-43.8). Seventeen of 37 surveyed hospitals routinely used interim evaluation. In a survey among 37 German university hospitals, 62% reported offering PRRT for GEP-NET patients, with 74% of these performing a routinely interim evaluation after 2 cycles of PRRT, primarily using PET/CT imaging techniques.

Conclusions: Interim PET after 2 PRRT cycles helps to identify early progression in GEP-NET patients. Standardizing interim evaluation practices could enhance the comparability of clinical outcomes and optimize patient management.