Abstract
OBJECTIVE: The aim of the study was to assess 177Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) in neoadjuvant setting in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). In addition, we also evaluated the variables associated with resectability of the primary following PRRT. MATERIALS AND METHODS: A total of 57 GEP-NETs with unresectable primary due to vascular involvement as defined using the National Comprehensive Cancer Network (NCCN) criteria given for pancreatic ductal adenocarcinoma (PDAC), who underwent 177Lu-DOTATATE without any prior surgery were included in this study. GEP-NETs were divided into two groups: Group1-without liver metastases (n = 23 patients) and Group2- with potentially resectable liver metastases (n = 34 patients). 177Lu-DOTATATE was administered with mixed amino acid-based renal protection with dose of 7.4 GBq (200 mCi) per cycle. Evaluation of surgical resectability following PRRT was done by using tri-phasic computed tomography (CT) imaging. Overall PRRT response was evaluated under four broad categories. The Kaplan–Meier product-limit method was used to calculate progression free survival (PFS) and overall survival (OS). Associations between variables and resectable primary after PRRT were analyzed by using Chi-square test at significant P value less than 0.05. RESULTS: Following 177Lu-DOTATATE, unresectable primary became resectable in 15 out of 57 (26.3%) patients {7 patients in group-1 and 8 patients in group-2}. Response (complete response and partial response) to PRRT was seen in 48 patients (84%), 23 patients (40%), 18 patients (31%) and 23 patients (40%) on symptomatic, biochemical, molecular imaging and anatomical imaging response evaluation criteria respectively. Estimated rates of PFS were 95% and 90% at 2 years in group1 and group2 patients respectively. The 2-years OS of combined both groups was 92.1%. Higher rate of resectable primary following PRRT was found in duodenal NET, GEP-NETs with absent regional lymph node involvement, size of primary<5cm, size of liver lesions ≤1.5 cm, number of liver lesions ≤3 and FDG uptake(SUVmax<5 in primary tumor) with significant P value. CONCLUSION: Thus, unresectable primary converted could be into resectable in a moderate fraction of GEP-NETs following 177Lu-DOTATATE, signifying that neoadjuvant PRRT could be considered in GEP-NETs patients with unresectable primary due to vascular involvement with or without liver metastases. Effective control of symptoms with favorable morphological and functional imaging response and durable PFS and OS following 177Lu-DOTATATE PRRT were important observation in our study, which may lead to less morbidity and mortality in these patients.
- Oncology: Pancreas
- Radionuclide Therapy
- 177Lu-DOTATATE
- 68Ga-DOTATATE PET/CT
- Gastroenteropancreatic neuroendocrine tumor (GEP-NET)
- Neoadjuvant PRRT
- Peptide receptor radionuclide therapy (PRRT)
- Copyright © 2021 by the Society of Nuclear Medicine and Molecular Imaging, Inc.