Lobectomy plus lobe-specific lymphadenectomy as the minimum standards of curative resection for hypermetabolic clinical stage IA non-small cell lung cancer.

Background: The results of three modern randomized controlled trials have proved sublobar resection as an effective procedure for early-stage non-small cell lung cancer (NSCLC) up to 2 cm. We aimed to examine whether sublobar resection is oncologically feasible and what constitutes adequate lymph node assessment for hypermetabolic clinical stage IA (cIA) NSCLC.

Methods: A single-center retrospective study was conducted in 589 patients who underwent lobectomy (n=526) or sublobar resection (n=63) for hypermetabolic cIA NSCLC [maximum standardized uptake value (SUVmax) ≥2.6 g/dL]. The primary outcomes (lung cancer-specific death and tumor recurrence) were compared in a competing risks framework for all patients and the propensity score matched pairs. Random forests were used to examine the variable importance for lung cancer-specific survival and tumor recurrence. Factors affecting pathological upstaging and recurrence-free survival were assessed by logistic regression analysis and Cox regression analysis, respectively.

Results: Sublobar resection had significantly higher lung cancer-specific cumulative incidence of death (LC-CID) and cumulative incidence of recurrence (CIR) than lobectomy after matching (5-year LC-CID, 20.8% . 6.5%, P<0.001; 5-year CIR, 37.9% . 14.8%, P<0.001). Wedge resection was an independent risk factor for both lung-cancer specific death [hazard ratio (HR) =4.17; 95% confidence interval (CI): 2.07-8.36; P<0.001] and recurrence (HR =3.48; 95% CI: 1.91-6.33; P<0.001). Lymphadenectomy that failed to meet the lobe-specific nodal dissection (LSND) criteria correlated with decreased odds of pathological nodal upstaging [odds ratio (OR) =0.55; 95% CI: 0.34-0.87; P=0.01]. While patients with LSND had lower LC-CIR and CIR, there was no additional prognostic benefit of systemic nodal dissection (SND) over LSND.

Conclusions: Lobectomy was oncologically superior to sublobar resection as a curative-intent procedure for hypermetabolic cIA NSCLC. Lobectomy plus lobe-specific lymphadenectomy should be considered as the minimum standards of curative resection for hypermetabolic early-stage NSCLC in order to achieve more accurate pathological N staging and better cancer control.