Background: According to the current clinical guidelines, chemoradiotherapy is considered the standard treatment for locally advanced non-small cell lung cancer (NSCLC). We analyzed the prognostic effect of adjuvant chemotherapy (ACT) in resected patients using the new eighth tumor node metastasis (TNM) staging systems based on the Surveillance, Epidemiology and End Results database.
Methods: We identified 3008 patients with stage IIIA NSCLC (T4N0M0) who underwent sublobar resection, lobectomy, or pneumonectomy. Covariates affecting treatment selection or survival were included as part of propensity score models for matching and weighting. The effect of ACT on survival was assessed, stratified by postoperative radiation therapy (PORT) use, tumor size, and age.
Results: Analyses of 2016 patients were conducted with standardized differences in covariates < 10% after matching. ACT was associated with significantly improved five-year overall survival (51.1% vs. 39.7%; P = 0.0260) in patients aged 21-65 with > 7 cm tumors, even after adjusting for the presence or absence of the superior sulcus (P = 0.0003). No significant outcomes were observed using other stratifications in the matched analysis. Moreover, ACT with PORT conferred a potential survival benefit in 21-65-year-old patients with 0-7 cm tumors (for all causes of death: hazard ratio 0.414, 95% confidence interval 0.251-0.684).
Conclusion: In this population-based cohort, ACT prolonged the survival of patients aged 21-65 with a tumor > 7 cm, with or without PORT. Inverse probability of treatment weighting can estimate the treatment effect and is suitable for use with survival data.
Keywords: Adjuvant chemotherapy; Surveillance, Epidemiology, and End Results (SEER) registry; inverse probability of treatment weighting; non-small cell lung cancer; survival.
© 2019 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.