Elevated prevalence of nodal positivity in carcinoid tumours of the appendix smaller than 2 cm has a negative impact on overall survival.

Abstract

The current standard of care for clinically node-negative carcinoid tumours of the appendix < 2.0 cm in size is appendectomy alone. The aim of this analysis was to evaluate the prevalence of pathological nodal positivity in clinically node-negative appendiceal tumour specimens < 2.0 cm and quantify the impact of occult pathological nodal positivity on overall survival following resection. A retrospective database review of the 2019 US National Cancer Database for appendiceal cancer identified 2007 cases of clinically node-negative appendiceal carcinoid tumours based on SEER histology codes 8240, 8241, 8242, 8243, 8243, 8244, 8245, 8246 and 8249. Kaplan-Meier with log-rank testing and multivariate Cox regression analysis evaluated the impact of occult nodal positivity on overall survival following resection for clinically node-negative appendiceal carcinoma. The prevalence of occult nodal positivity increased from 1.9% for sub-centimetre tumours to 7% for tumours between 1.0 and 1.5 cm, 16.5% for tumours between 1.5 and 2.0 cm and to >29.5% for tumours > 2.0 cm. Rates of metastatic spread were similar for tumours < 2.0 cm but increased for larger tumours. Over two-thirds of patients received a segmental colectomy as definitive surgical therapy. After controlling for differences in cohorts, multivariate analysis showed an increased hazard ratio for mortality of 162% (HR 2.62, CI 1.884-3.541) for patients with pathological node-positive disease. Clinically node-negative carcinoid tumours of the appendix bigger than 1.5 cm have an increased rate of occult nodal spread which has a negative impact on overall survival.