Prognostic significance of examined lymph node count in older patients with stage T1N0M0 pulmonary carcinoid tumours: a population-based propensity score-matched analysis.

ABSTRACT

BACKGROUND: The optimal number of examined lymph nodes (ELNs) for older early-stage pulmonary carcinoid tumour (PC) patients is unknown. AIMS: To explore the prognostic effect of the ELN count in older patients with stage T1N0M0 PC resection. METHODS: Clinical data from the Surveillance, Epidemiology, and End Results database on stage T1N0M0 PC older patients (age ≥ 65 years) who underwent sublobar resection and lobectomy between 2000 and 2018 were retrospectively analysed for two ELNs-stratified (≥ 7 vs. < 7 ELNs) propensity score-matched (PSM) groups. Overall survival (OS) was calculated and compared with Kaplan-Meier analysis and log-rank test, respectively, and the independent prognostic factors were estimated using a Cox proportional hazard model. RESULTS: Among 1077 participants (median dissected LN 4; mean ELNs 6.19 ± 7.04), 393 (36.49%) in the ≥ 7 ELNs group had better 5- and 10-year OS than the < 7 ELNs group (before PSM 5-year OS = 93.01 vs. 85.22%, 10-year OS = 72.38 vs. 58.99%, p < 0.001; after PSM 5-year OS = 93.12 vs. 85.97%, 10-year OS = 75.25 vs. 60.03%, p = 0.001). Subgroup analysis stratified by histologic type and surgical method showed a similar survival trend. Age-stratified analysis showed that, compared with the < 7 ELNs group, the ≥ 7 ELNs group had better 5- and 10-year OS but only better 5-year OS in participants > 75 years. Compared with the < 7 ELNs group, subgroup analysis by tumour size showed superior OS with 1.1-3.0 cm tumours in the ≥ 7 ELNs group, but no significant intergroup difference with tumours < 1.0 cm. Multivariate Cox analysis showed ≥ 7 ELNs was associated with improved OS. CONCLUSION: Higher ELNs correlated with increased long-term survival in older early­stage PC patients, and a minimum of 7 ELNs are recommended for prognostication in these patients (especially those aged 65-75 years, with tumour size 1.1-3.0 cm).