Does Examined Lymph Node Count Influence Survival in Surgically Resected Early‑stage Pulmonary Typical Carcinoid Tumors?

Abstract

We aimed to evaluate the prognostic impact of the number of examined lymph nodes (ELNs) in resected early‑stage pulmonary typical carcinoid tumors (TC). Patients who underwent sublobar resection and lobectomy for stage T1N0M0 TC between 2004 and 2016 were identified from the Surveillance, Epidemiology, and End Results database and enrolled in the ELNs≥4 or ELNs<4 groups (optimal cutoff using X-tile). Propensity score matching balanced baseline intergroup characteristics. Kaplan-Meier curve and log-rank test were used to calculate and compare overall survival (OS) rates. Cox proportional hazard model analysis was used to identify independent prognostic factors. Among 2234 participants, 961 (43.02%) and 1273 (56.98%) had ELNs <4 and ≥4, respectively. The 5-year OS was significantly higher in the ELNs≥4, compared with ELNs<4, group, both before and after propensity score matching (95.41% vs. 89.71%, P<0.001 and 95.24% vs. 90.28%, P=0.004), respectively. Surgical subgroup analysis confirmed this survival trend in the lobectomy and sublobar resection groups. Tumor size-based subgroup analysis revealed superior OS with ELNs≥4 than ELNs<4 for tumors measuring 1.1-3.0cm but not for tumors <1.0cm. Multivariate Cox analysis showed that ELN≥4 contributed to improved OS. The higher the ELNs, the greater the long-term survival rate in patients with early‑stage TC. Therefore, we recommend at least 4 ELNs as the cutoff value for evaluating the prognosis of early‑stage TCs, especially for patients with a tumor size of 1.1 to 3.0cm.