Oncological outcomes of left upper trisegmentectomy versus lobectomy for clinical stage I non–small cell lung cancer with occult lymph node metastasis: A target trial emulation with targeted minimum loss–based estimation and propensity score matching

Objective: To determine whether left upper trisegmentectomy is comparable to left upper lobectomy in terms of long-term survival among patients with clinical stage I non–small cell lung cancer who are found postoperatively to have occult lymph node metastasis. Methods: We emulated a hypothetical target trial using retrospective data from the West China Lung Cancer Database (2013-2024). Patients with tumors located at least 2 cm from the lingular segment who were postoperatively found to have occult lymph node metastasis were included. The primary end point was overall survival (OS), while secondary end points included progression-free survival, lung cancer–specific survival, and perioperative outcomes. We applied targeted minimum loss–based estimation (TMLE) and propensity score matching to analyze the causal effect of the surgical procedure. Results: A total of 1019 patients were included (lobectomy, 524; trisegmentectomy, 495) with a median follow-up of 5.9 years (interquartile range, 4.2-7.3). Perioperative outcomes were comparable between groups, with no significant differences in operative time (154 vs 146 minutes; P = .349) or complication rates (16.2% vs 12.1%; P = .305). While trisegmentectomy was associated with a significantly higher rate of local recurrence compared to lobectomy (43.4% vs 30.1%; P < .001), no significant differences were observed in TMLE-adjusted 5-year OS (66.5% vs 67.9%; P = .821), 5-year progression-free survival (54.3% vs 52.8%; P = .834), or 5-year lung cancer–specific survival (69.1% vs 72.1%; P = .487). Conclusions: Left upper trisegmentectomy provides survival outcomes comparable to lobectomy in patients with clinical stage I disease and occult nodal metastasis, although associated with higher local recurrence rates.