Survival and Response Outcomes for Gastrointestinal Neuroendocrine Tumor (GEP-NETs) Patients Treated with Lutetium-177-DOTATATE in a Brazilian Reference Center: A Six-Year Follow-Up Experience

Simple Summary Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are the most common primary site of NETs. Peptide receptor radiation therapy with Lutetium-177-DOTATATE (PRRT) is the standard treatment for grade 1 (G1) or grade 2 (G2) midgut NETs when somatostatin analog therapy fails, but limited data exists on all-grade GEP-NETs, especially for grade 3 (G3) tumors. Here, we aimed to review the clinical-pathological and radiological characteristics of those tumors and correlate them with outcomes. That might help with how to select patients for PPRT.Abstract Background: PRRT can be an option for all-grade GEP-NETs, but selecting patients is challenging. In this scenario, clinical-pathological and radiological characteristics, such as pre-treatment Ga-68 DOTA PET/CT, might have the potential to help. Methods: A retrospective chart review was conducted on advanced GEP-NETs treated with at least one PRRT dose. Overall survival (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier method. Krenning Score (KS), and the maximum standardized uptake value (SUVmax) were derived from the pre-treatment scans. A maximally selected rank statistics test was used for SUVmax simple cut point estimate. Results: Among 36 patients, 19 had primary pancreatic tumors. The numbers of G1, G2, and G3 tumors were 10, 18, and 7, respectively. During a median follow-up of 90.5 months, 4 patients died. Median OS was not reached for G1 and G2 tumors, and it was 30 months for G3 (p = 0.001). Median PFS was 23 months, with G3 showing lower PFS compared to G1 [7 versus 30 months; HR 8.41 (95%CI 2.2-31.0; p = 0.001)]. Conclusions: PRRT provides long-term PFS in patients with G1/G2 GEP-NETs independent of clinical characteristics and primary site. G3 has worse survival, but selected patients may experience long OS after PRRT treatment.