Lymph Node Dissection Guideline Adherence and Survival in Patients With T1N0M0 Lung Adenocarcinoma

Importance: Lymph node dissection for early-stage lung adenocarcinoma is controversial. Histologic pattern subtyping reveals heterogeneity of lung adenocarcinoma, yet its association with lymph node involvement and dissection is understudied. Objective: To assess the association between guideline-adherent lymph node dissection, histologic pattern subtyping, and overall survival in patients with clinical T1N0M0 lung adenocarcinoma. Design, Setting, and Participants: This multicenter cohort study used data from the National Cancer Center LungReal database, a multicenter, electronic health records-based database for patients undergoing surgery for lung cancer, from January 2014 to December 2021, with the last follow-up in December 2022. Patients were categorized based on histologic pattern of adenocarcinoma into 2 groups: lepidic without high-grade pattern, and high-grade or no lepidic pattern. The data analysis was performed from April to November 2025. Exposure: Lymph node dissection adherence or nonadherence with the 3 + 1 standard (3 N2 plus 1 N1 station) and the 6-station standard (the subcarinal plus 2 other N2 stations and 3 N1 stations). Main Outcome and Measure: Overall survival. Results: Of 35 265 patients screened, 27 191 participants (mean [SD] age, 58.3 [11.7] years; 16 280 female [59.9%] and 10 911 male [40.1%] individuals) from 19 centers were included; among them, 15 593 (57.3%) received lymph node dissection adherent with the 3 + 1 standard and 4023 (14.8%) with the 6-station standard. Among the group of 13 369 patients (49.2%) with adenocarcinoma of lepidic without high-grade pattern, no association was observed between survival and adherence with the 3 + 1 standard (hazard ratio [HR], 0.81; 95% CI, 0.57-1.15) or the 6-station standard (HR, 0.54; 95% CI, 0.26-1.13). Whereas, among the group of 13 822 patients (50.8%) with adenocarcinoma of high-grade or no lepidic pattern, adherence with the 3 + 1 standard (HR, 0.81; 95% CI, 0.69-0.95; absolute risk difference at 3-year, 1.2%; 95% CI, 0.2%-2.2%; E-value, 1.78) or the 6-station standard (HR, 0.61; 95% CI, 0.45-0.83; absolute risk difference at 3 years, 1.0%; 95% CI, 0.1%-1.9%; E-value, 2.67) was associated with a significant but small absolute survival benefit. Conclusion and Relevance: In this cohort study, guideline-adherent nodal dissection was associated with small absolute survival benefit for patients with adenocarcinoma of high-grade or no lepidic pattern, but not for those with lepidic without high-grade pattern. These observational findings warrant prospective validation and should not be interpreted as causal.