Establishing a prognostic scoring system and exploring prognostic value of examined lymph node numbers for stage I non-small cell lung cancer: a retrospective study of Surveillance, Epidemiology, and End Results (SEER) database and a Chinese cohort.

Background: There is currently no recognized assessment system to predict disease outcomes for stage I non-small cell lung cancer (NSCLC). This research aimed to develop a prognostic scoring system for predicting 5-year overall survival (OS) of individuals with stage I NSCLC following definitive therapeutic intervention. Additionally, the optimal number of examined lymph nodes (ELNs) count for tumors no larger than 30 mm was determined.

Methods: Patients (n=22,617) diagnosed with stage I NSCLC from 2007 to 2015 who underwent definitive treatment (pulmonary lobectomy, pulmonary sublobectomy, or radiotherapy) were identified from the Surveillance, Epidemiology, and End Results (SEER) database. There were 400 Chinese patients with stage I NSCLC diagnosed in 2017 enrolled for external validation. The nomogram was constructed based on gradient boosting machine. The optimal ELNs in patients with tumors ≤30 mm and node-negative undergoing pulmonary lobectomy or pulmonary sublobectomy were determined using log-rank test and validated by multivariable analysis.

Results: Age at diagnosis, histology, differentiated grade, tumor staging, number of ELNs, and definitive treatment pattern were recognized as important factors for 5-year OS. The prognostic scoring system exhibited superior discrimination accuracy, calibration ability, and net clinical benefit compared to the tumor, node, metastasis (TNM) staging system. For patients with tumors ≤30 mm, more than 10 and 20 ELNs demonstrated the maximum OS difference during lobectomy and sublobectomy, respectively.

Conclusions: This prognostic scoring system will anticipate the prognosis of stage I NSCLC patients after radical treatment, thereby offering individualized treatment recommendations for both clinicians and patients. A minimum of 10 ELNs during lobectomy and 20 ELNs during sublobectomy are necessary for small-sized NSCLC.