Adequate Number of Lymph Nodes Sampled May Determine Appropriate Surgical Modality for Early-Stage NSCLC: A Population-Based Real-World Study

The number of lymph nodes sampled and surgical modality for < 2 cm early-stage NSCLC were estimated. Patients from SEER database were analyzed and external validation from our hospital was performed. Mediastinal lymph node dissection is rather needed when conducting a sublobectomy for patients with T1a-bN0M0 NSCLC. On the premise of nLN > 7, sublobectomy could provide similar survival outcomes with lobectomy. Background: The standard surgical procedure for < 2 cm non-small cell lung cancer (NSCLC), including the number of lymph nodes sampled (nLN) and surgical modality, remains controversial. This study was designed to determine the optimal cohort in which sublobectomy could be an alternative to lobectomy. Materials (or Patients) and Methods: Patients from 1998 to 2017 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. The optimal cutoff value of nLN was identified using a restrictive cubic spline graph (RCS). Kaplan-Meier analysis was used to determine cancer-specific survival (CSS). The COX proportional hazard regression model was used to identify the influence of clinical and demographic variables on survival, and propensity score matching (PSM) was used to balance differences in baseline characteristics. Finally, we used an external cohort from a single-center medical institution to verify the conclusions drawn from the SEER database. Results: A total of 6150 patients were included. The sublobectomy subgroup included segmentectomy (308, 5.0%) and wedge resection (1611, 26.2%). The cutoff value for nLN was 7. In the nLN >7 subgroup of the PSM cohort, the CSS of segmentectomy and wedge resection was close to that of the lobectomy subgroup ( P = .12), whereas in the nLN < 7 subgroup, the CSS of the lobectomy subgroup was significantly higher than that of the sublobectomy with P < .001). Surgical methods, nLN, age, sex, and differentiated grade were independent predictors of CSS. External cohort validation: A total of 1106 patients from the Affiliated Jinhua Hospital of Zhejiang University School of Medicine between 2013 and 2020 were included. The grouping cr iter ia were consistent with the SEER database. In the nLN >7 subgroup, sublobectomy had a survival outcome similar to that of lobectomy ( P = .81). Conclusion: Sublobectomy and nLN < 7 were strongly associated with poorer CSS for earlystage NSCLC. On the premise of nLN > 7, sublobectomy could provide similar survival outcomes to lobectomy for these patients.