Endocrine Abstracts (2016) 46 P28 | DOI: 10.1530/endoabs.46.P28

Outcome of Surgical Resection after Neoadjuvant Peptide Receptor Radionuclide Therapy (PRRT) for Pancreatic Neuroendocrine Neoplasms: a case-matched analysis

Stefano Partelli1, Emilio Bertani2, Mirco Bartolomei3, Francesca Muffatti1, Chiara Maria Grana2, Claudio Doglioni1, Nicola Fazio2 & Massimo Falconi1

1San Raffaele Scientific Institute, Milan, Italy; 2European Institute of Oncology, Milan, Italy; 3”M. Bufalini” Hospital, Cesena, Italy

Background: Peptide receptor radionuclide therapy (PRRT) can be an option for advanced pancreatic neuroendocrine neoplasms (PNENs) to allow patients undergo resection. Whether or not neoadjuvant PRRT increases postoperative morbidity remains unclear.

Methods: Patients with initially metastatic and/or locally advanced PNEN who underwent neoadjuvant PRRT (neoadjuvant group) were compared with a group of patients who underwent upfront surgery (control group). Patients were matched for tumor size, grading, staging, and intent of resection.

Results: Overall, 20 patients underwent sequential PRRT and pancreatic resection. The reason for neoadjuvant PRRT was the presence of liver metastases in 6 patients (30%), the presence of organ/vascular infiltration in the remaining 14 (70%). After PRRT the median tumor size decreases from 59 mm to 50 mm (P=0.047). The majority of patients (n=15) underwent distal pancreatectomy whereas the remaining 5 underwent pancreaticoduodenectomy. The rate of curative resection was 65%. Histology revealed a PNEN-G1 in 10 cases, a PNEN-G2 in 7 patients, and a PNEC-G3 in 3 patients. Preoperative and postoperative tumor grading was concordant in 13 patients whereas 5 patients were upstaged and 2 patients were downstaged. Patients who underwent neoadjuvant PRRT had a lower risk of developing pancreatic fistula (25% versus 65%, P=0.011) although the rate of overall complications was similar (45% vs 60%, P=0.342). The two groups had similar distribution of tumor grading, T stage, TNM stage, R2 resection, microvascular invasion, perineural invasion, and necrosis. Patients who underwent upfront surgery were more likely to have nodes metastases (80% versus 35%, P=0.004). The 2-year progression free survival rate was 67% for the neoadjuvant group versus 58% in the control group (P=0.319). Independent predictors of progression free survival were PNEC-G3 and stage IV tumor.

Conclusions: Pancreatic resection for PNEN after neoadjuvant PRRT is safe and associated with a lower risk of developing pancreatic fistula.