Resident Physician Stanford Mountain View, California, United States
Disclosure(s):
Lye-Yeng Wong, MD: No financial relationships to disclose
Purpose: Sublobar resection (SR) is increasingly considered appropriate for treating early-stage non-small cell lung cancer (NSCLC) but may increase the risk of positive margins compared to lobectomy. Our study evaluated the relationship between resection extent, margin status, and survival for patients with clinical stage I NSCLC. Methods: All patients in the National Cancer Database from 2004-2020 treated with primary surgery via sublobar resection or lobectomy for clinical T1-2N0M0 NSCLC were compared stratified by margin status. Independent predictors of having positive margins were evaluated with multivariable logistic regression. The impact of positive margins on survival was assessed with Cox modeling. The potential benefit of radiation therapy was explored in subgroup analysis of sublobar resection patients with positive margins, whose survival was also compared to negative margin lobectomy patients. To control for selection bias in surgical approach, the incidence and prognostic effect of positive margins was validated by propensity matching based on age, sex, race, tumor size, clinical T stage, Charlson comorbidity index, insurance type, facility type, and distance to facility. Results: Positive margins occurred in 5,089 (2.8%) of 181,824 patients and were more common in SR versus lobectomy (4.3% vs 2.4%,p < 0.001). SR had the strongest independent association with positive margins in logistic regression analysis (OR 2.06 [95% CI 1.91-2.23],p < 0.001), while increasing age, more comorbidities, tumor size, and facility type were also significant predictors. Patients with positive margins were more likely to undergo adjuvant chemotherapy (16% vs 13%,p < 0.001) and radiation (17% vs 1%,p < 0.001) but had worse survival in univariate (44.0% 5-year OS vs 69.2%,p < 0.001) and multivariable Cox analysis (HR 1.71 [95% CI 1.63-1.78,p < 0.001) in the entire cohort (Table), as well as in univariate subset analysis of lobectomy (46.9% vs 70.4%,p < 0.001) and SR (37.5% vs 64.1%,p < 0.001) (Figure 1A). Use of adjuvant radiation for SR patients with positive margins did not improve 5-year OS (36.3% for irradiated vs 38.3% for non-irradiated patients,p=0.57), and positive margin SR patients treated with radiation had inferior survival to negative margin lobectomy patients (Figure 1B). In the propensity matched analysis, SR patients continued to have higher incidence of positive margins (4.3% vs 2.2%,p < 0.001), and the impact of positive margins on survival were consistent with the results from the entire cohort. Conclusion: Positive margins occur more frequently after sublobar resection of clinical stage I NSCLC compared to lobectomy. Patients with positive margins have much worse survival than complete resection patients and are not rescued by post-operative radiation. Sublobar resection use for early-stage NSCLC therefore must not compromise margin status.
Identify the source of the funding for this research project: None
