Long-term results after surgical resection of peritoneal metastasis from neuroendocrine tumors

Introduction: Peritoneal metastases from neuroendocrine tumors are associated with a bad prognosis. The objective of our study was to evaluate whether surgical resection could lead to prolonged survival in selected patients. This survival was compared to that of patients operated for liver metastasis. Methods: From our prospectively maintained database we included 88 patients who underwent the complete resection of peritoneal and/or liver metastasis between January 1995 and December 2016 in Gustave-Roussy. Three resection groups were compared: peritoneal metastasis alone, liver metastasis alone, and the combined resection of liver and peritoneal metastases. Results: The median peritoneal cancer index was 10 in the peritoneal group and 11 in the peritoneal + liver group. The 5-year overall survival was 81% (60-100) in the peritoneal group compared to 78% (65.2-92.8) in the liver group, and 72% (58.7-89.7) in the peritoneal + liver group (p = 0.71). The 3-year disease-free survival reached 26.9% (16.1-45.1) in the liver group, 12.5% (2.3-68.2) in the peritoneal group, and 32.4% (19.9-52.6) in the combined liver + peritoneal group (p = 0.45). In the univariate analysis, the prognosis factors for a longer survival were: small bowel primary tumor origin, low preoperative chromogranin A level, and tumor grade ≤1. Conclusion: Despite a high recurrence rate, long-term overall survival can be achieved after the resection of peritoneal metastasis in selected patients. This survival is comparable to that of patients operated for liver metastasis only. Surgery should stand as a standard treatment for peritoneal metastases in patients with resectable disease.