Real-World Outcomes After Sublobar Resection for Small Node-Negative Lung Adenocarcinoma: SEER Benchmarking and a Clinicopathological Analysis

Background: Randomized trials support sublobar resection for selected small peripheral lung cancers, but real-world outcomes may vary by procedure type, nodal assessment, and pathological risk. Methods: We performed a two-stage real-world analysis. Stage 1 included 22,864 patients with lung adenocarcinoma ≤3 cm from a node-assessed N0M0 SEER cohort. Stage 2 included 872 patients with node-negative lung adenocarcinoma from a multi-institutional, single-center-dominant clinicopathological cohort. The primary endpoint was disease-free survival (DFS). Results: In SEER, sublobar resection was associated with higher all-cause mortality (HR 1.31, 95% CI 1.23–1.38) and lung cancer-specific death (HR 1.38, 95% CI 1.27–1.51). Procedure-specific estimates were smaller for segmentectomy than for wedge resection and were attenuated after adjustment for examined lymph-node count. In the clinicopathological cohort, the primary postoperative model showed a higher DFS hazard with sublobar resection (HR 1.75, 95% CI 1.08–2.83), with a similar estimate after overlap weighting (HR 1.75, 95% CI 1.08–2.85). However, the association was not statistically clear after propensity-score matching (HR 1.41, 95% CI 0.76–2.63), 60-month restriction (HR 1.09, 95% CI 0.58–2.03), or restriction to a comparable-follow-up cohort (HR 1.57, 95% CI 0.88–2.78). The proportional-hazards assumption for DFS was violated, and late estimates were based on sparse risk sets and were unstable. The recurrence association was predominantly locoregional, and increasing Core-HRPF burden was associated with progressively worse prognosis. Conclusions: Real-world sublobar resection is a heterogeneous exposure. Observed outcome associations varied by procedure type, nodal assessment, analytical specification, and follow-up horizon and should not be interpreted as evidence that sublobar resection is intrinsically inferior to lobectomy.