Prognostic significance of lymph node sampling in node-negative appendiceal carcinoids.

Abstract

678 Background: Surgical resection is the primary therapy for local and locally advanced carcinoid tumors of the appendix. The extent of surgery is largely dictated by the size of the tumor. Tumors >2 cm require a right hemicolectomy with associated mesenteric lymphadenectomy. What constitutes an adequate mesenteric lymphadenectomy is not known. Methods: This is a study of a contemporary cohort from NCI’s SEER database (Jan, 2004- Nov, 2012). Patients with non-metastatic appendiceal carcinoid tumors were included. Surgical extent was defined as limited (appendectomy or illeocecectomy) or extended (hemicolectomy). Primary outcome was overall survival (OS). Survival analysis was performed using the Kaplan-Meier and Cox-proportional hazards model. Results: Of the total 1,104 patients that met the inclusion criteria, 52% were female, 88% were white and majority were middle aged (40-60y) 45%. Majority of the tumors were <2 cm (49.3%) and lymph node(LN) negative 85%. Median LN retrieved were 10 (IQR 0-17). Median follow-up was 32 months (IQR 10-61). A multivariate Cox-proportional hazard model demonstrated that increasing age, tumor size > 3cm, tumor spread to contiguous organs, LN positivity and LN count <11 (HR 1.78: 95%CI 1.17-2.69; p=0.006) are associated with worse OS. Five-year overall survival increased with the number of LN retrieved (LN 1-10, 81.4%; LN >10, 85.9%, p=0.035). Stratified analysis by LN status demonstrated that LN count <11 was an independent predictor of worse OS in node negative patients (HR 2.10: 95%CI 1.25-3.53; p=0.005) but not node positive patients (p=0.65). Subset analysis by tumors size demonstrated that prognostic value of LN count <11 was only significant for tumors greater than 3 cm (HR 2.32: 95%CI 1.15-2.03; p=0.018). Conclusions: This is the largest study to date that looks at prognostic significance of LN count for appendiceal carcinoids. The number of LNs evaluated is an independent prognostic factor in pathologic node-negative, appendiceal carcinoid tumors measuring greater than 3 cm. This data supports performing a formal lymphadenectomy (>10 LN) even if no mesenteric disease is visible for adequate staging.