Surgery and peptide receptor radionuclide therapy: An effective multimodal approach for metastatic neuroendocrine tumors.

Abstract

4113 Background: Neuroendocrine neoplasia (NEN) of the pancreas (PanNEN) or small bowel (SBNEN) frequently present with metastases at initial diagnosis, undermining the efficacy of surgical treatment. Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues, 90Y-DOTATOC and 177Lu-DOTATATE, has been shown to achieve prolonged progression-free survival (PFS) and overall survival (OS) in a substantial number of non-surgical patients with advanced NEN. Our aim was to prospectively determine the efficacy of a combination of radical loco-regional surgery and 177Lu PRRT in patients with metastasised NEN. Methods: A set of inclusion criteria was defined (e.g. PanNEN or SBNEN, G1/G2 NEN, initial tumour diagnosis, treatment naïve patient, stage IV NEN, positivity on 68Ga DOTATATE or DOTATOC PET/CT, eligibility for surgery and PRRT). Patients underwent PRRT within 3 months following surgery. Follow-up included biochemistry and imaging. Outcome measures included 1-, 3-, and 5-year OS and PFS from initial diagnosis. Results: Forty-one patients met eligibility criteria and were included. There were 26 males (63.4%) and median age at surgery was 58.8 years (range 32.1-78.3). All patients with SBNEN underwent right hemicolectomy, terminal ileal resection and mesenteric lympadenectomy. In PanNEN patients either Whipple procedure or distal pancreatectomy and peripancreatic lymphadenectomy were performed. The median number of PRRT cycles was 4 (range 2-6). Post-treatment mortality was 0%. Surgical morbidity was 12% (all grade 1 according Clavien-Dindo) and transient grade 1 toxicity occurred post PRRT in 40%. There was no grade 3 toxicity. Median follow-up was 5.48 years (range 0.53 – 11.98). Median PFS and OS were 3.33 years and 9.07 years, respectively. Progression-free survival (with 95% CI) was at 1-, 3-, and 5-years 80% (68.7-92.6), 60.9% (45.9-75.9) and 43.3% (27.4-59.3), respectively. Overall survival (with 95% CI) at 1-, 3-, and 5-years was 97.6% (93-100), 97.6% (93-100), and 95% (87-100), respectively. Conclusions: Radical loco-regional surgery for primary tumours combined with PRRT provides a novel, highly efficacious approach in metastasised NEN.