Long-Term Survival is not Impaired After the Complete Resection of Neuroendocrine Tumors of the Appendix

Appendiceal neuroendocrine tumors (aNET) are a common entity in routine medical care, with a rate per appendectomy as high as 0.3-0.9 %. Considering the relatively young age at diagnosis for these patients, exact information about the long-term prognosis of aNET is required. Survival rates vary substantially between 71 and 100 % and are mostly limited to 5 years. This investigation assessed the long-term mortality rates of patients who underwent aNET resections at fifteen hospitals. Between 1990 and 2003, the 10-year survival rates of 79 patients were analyzed using risk-adjusted Cox proportional hazard regression models adjusted for population-based baseline mortality. Additionally, prognostic factors for the oncologic outcomes were assessed. The median follow-up of all patients was 12.1 and 13.7 years for those alive. All patients underwent curative R0 resections. No distant metastases were diagnosed. A total of 31 (39.2 %), 29 (36.7 %), 18 (22.8 %), and 1 (1.3 %) patients had stage I, IIA, IIB, and IIIB aNET, respectively, according to the latest classification by the European Neuroendocrine Tumor Society. The 10-year overall and relative survival rates were 83.6 % (95 % CI 75.5-92.6 %) and 96.7 % (95 % CI 87.5-107 %), respectively. The 10-year relative survival rate after resection of aNET did not differ from the survival of the average national population with the same age and gender (p = 0.947). Second primary malignancies (hazard ratio of death 7.0, 95 % CI 1.6-30.6) were identified as a significant prognosticator for long-term survival. Long-term survival is not significantly depreciated after the curative resection of aNET.