Appendiceal neuroendocrine tumors: approach and treatment

Abstract

The incidence of tumors in the appendix has increased over the years, and they are mainly found in the anatomical and pathological examination of appendices operated due to acute appendicitis. The annual incidence of neuroendocrine tumors of the appendix, also called carcinoid tumors, is 0.15–0.16 per 100,000 people. In absolute terms, the incidence of these tumors has increased in the last decade by 70–133%. Appendiceal carcinoid tumors occur more often in women, and are found in 0.3–0.9% of the appendices removed in appendectomies. They appear in the subepithelial neuroendocrine cells and have an indolent course, with the symptoms being indistinguishable from an acute appendicitis. There are two classifications, one presented by the European Neuroendocrine Tumor Society and the other by the American Joint Committee on Cancer. Both classifications use tumor size as a predictor of tumor burden. The classification used by European Neuroendocrine Tumor Society also uses the invasion of the mesoappendix to select the best surgical treatment. However, these classifications require the inclusion of more criteria to define the selection of surgical treatment of tumors between 1 and 2 cm. Thus, along with the size of the tumor and the invasion of the mesoappendix, other factors such as vascular invasion, ki67 index, mitotic index and tumor location should be considered at the time of classification, for a better selection of the treatment and prognostic evaluation.