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

Objectives: We aimed to evaluate the prognostic impact of the number of examined lymph nodes (ELNs) in resected early‑stage pulmonary typical carcinoid tumors (TC).

Methods: 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.

Results: 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 1.1-3.0 cm but not for tumors <1.0 cm. Multivariate Cox analysis showed that ELN≥4 contributed to improved OS.

Conclusions: 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 3.0 cm.