Lepidic pattern as a favorable prognostic factor in pathologically high-risk stage I invasive lung adenocarcinoma.

BACKGROUND: The prognostic value of lepidic pattern in small stage I lung adenocarcinoma (LUAD) with pathological high-risk features remains unclear. This study evaluated whether lepidic pattern was associated with improved survival outcomes in this pathologically high-risk population. METHODS: Consecutive patients with surgically resected stage I invasive LUAD measuring ≤3 cm at West China Hospital, Sichuan University, between January 2018 and April 2025 were retrospectively reviewed. Patients with at least one pathological high-risk feature were included and stratified according to the presence or absence of lepidic pattern. Recurrence-free survival (RFS) and overall survival (OS) were compared before and after propensity score matching. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: A total of 1,233 patients were included, including 412 without lepidic pattern and 821 with lepidic pattern. After 1:1 propensity score matching, 315 matched pairs were generated. The median follow-up duration was 44 months. In the overall cohort, patients with lepidic pattern had better RFS than those without lepidic pattern, with 3-year RFS rates of 96.8% and 87.0%, respectively, and estimated 5-year RFS rates of 94.0% and 81.9%, respectively (HR, 0.42; 95% CI: 0.25-0.70; P<0.001). This association persisted after matching, with 3-year RFS rates of 96.3% and 86.6%, respectively, and estimated 5-year RFS rates of 92.2% and 81.2%, respectively (HR, 0.37; 95% CI: 0.20-0.69; P=0.001). In multivariable analysis, lepidic pattern remained independently associated with improved RFS (adjusted HR, 0.42; 95% CI: 0.25-0.70; P=0.001). OS was not significantly associated with lepidic pattern after matching or multivariable adjustment. CONCLUSIONS: Lepidic pattern was independently associated with improved RFS, but not OS, in patients with pathologically high-risk small stage I LUAD. Lepidic pattern may serve as a complementary histologic marker for postoperative recurrence risk stratification.