The EXPeRT Diagnostic And Therapeutic Recommendations For Appendiceal Neuroendocrine Tumors In Children And Adolescents

Background and Aims: Well-differentiated neuroendocrine tumors of the appendix (aNETs) are diagnosed incidentally following an appendicitis or opportunistic appendectomy. In the past, cases with risk factors (size, age, vascular or mesentery invasion) underwent right hemicolectomy with mesenteric lymphadenectomy. This represents an overtreatment considering that the clinical course is favourable in all cases regardless of risk factors or second surgery. The aim of this initiative is to develop internationally harmonized recommendations for the diagnosis and treatment of well-differentiated appendiceal neuroendocrine tumors (aNET) in children and adolescents, under the umbrella of the the European Group for the Study of Rare Tumors (EXPeRT). Methods: The EXPeRT promoted the formation of a working group to develop diagnostic-therapeutic recommendations. These recommendations were finalized after a review of the literature, and on the base of the Consensus Conference Standard Operating Procedure Methodology, in which levels of evidence and degrees of recommendation are considered for each suggested therapeutic intervention. Results: Appendectomy is curative in all patients regardless of the presence of risk factors (size, suspected residual, etc.). Multidisciplinary discussion is recommended in all cases with diameter > 2 cm or marginal resection. Right hemicolectomy or other kind of surgeries could be considered only in a very limited group of selected patients and after multidisciplinary discussion. Follow-up should be reserved only for cases with risk factors, and the use of tumor markers and functional imaging are not useful in the pediatric population, where all cases are low-risk localized aNETs. Conclusions: Surgery of aNETs should be limited to appendectomy in almost all cases, and follow-up should also be reserved for patients with risk factors (>2 cm, residual suspicion, grade 3).