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.