Disease relapse in relation to lymph node sampling in lung carcinoid patients

The predictive value of extent of per-operative lymph node (LN) sampling in relation to disease relapse in patients with pulmonary carcinoid (PC) is unknown. Furthermore, post-surgery follow-up recommendations rely on institutional retrospective studies with rather short follow-up. We aimed to address these short-comings by examining the relation between LN sampling and relapse in a population-based cohort with long-term follow-up. By combining the Dutch nation-wide pathology and cancer registries, all patients with surgically resected PC (2003-2012) were included in this analysis (last update 2020). Extent of surgical LN dissection was scored for number of LN sampled, location (hilar/mediastinal), and completeness of resection according to European Society of Thoracic Surgeons (ESTS) guidelines. Relapse free interval (RFI) was evaluated using Kaplan Meier and multivariate regression analysis. 662 patients were included. Median follow-up was 87.5 months. Relapse occurred in 10% of patients, mostly liver (51.8%) and locoregional sites (45%). Median RFI was 48.1 months (95% CI 36.8-59.4). Poor prognostic factors were atypical carcinoid, pN1/2 and R1/R2 resection. In 546 patients LN dissection data could be retrieved; at least one N2 LN was examined in 44% and completeness according to ESTS in merely 7%. In 477 cN0 patients, 5.9% had pN1 and 2.5% pN2 disease. In this population-based cohort, relapse occurred in 10% of PC patients with a median RFI of 48.1 months thereby underscoring the necessity of long-term follow-up. Extended mediastinal LN sampling was rarely performed but systematic nodal evaluation is recommended as it provides prognostic information on distant relapse.