Comparative survival analysis of platinum-based adjuvant chemotherapy for early-stage squamous cell carcinoma and adenocarcinoma of the lung

Background and Purpose: Although cytotoxic platinum-based adjuvant chemotherapy (pACT) has been recommended for patients with completely resected early-stage (ES) non–small-cell lung cancer (ES-NSCLC), therapeutic regimens for NSCLC have evolved in the past two decades. The study was aimed to examine the effectiveness of postoperative pACT for resected ES-NSCLC patients with squamous cell carcinoma (SCC) or adenocarcinoma (ADC) according to real-world data. Methods and Patients: Inverse probability treatment weighting (IPTW) was used to adjust baseline characteristics between the group receiving pACT and those not receiving any treatment (observation, OBS) within 3 months after curative surgery. Cox regression models were used to compare overall survival (OS) and treatment failure-free survival (TFS) between the groups. Results: Of 31,208 patients with ES-NSCLC, 4700 undergoing complete tumor resection were eligible, with a mean follow-up period of 4.5 years. The pACT (n = 2347) and OBS (n = 2353) groups were well-balanced after IPTW. The median OS differed between the pACT and OBS groups (77.2 vs. 75.5 months, adjusted hazard ratio [aHR] = 0.87, 95% confidence interval [CI] = 0.79–0.95, p = 0.003), and the 5-year survival rates were 58.2% and 55.3%, respectively (p < 0.001). In the SCC group, pACT was superior to OBS in OS (75.0 vs. 57.4 months, aHR = 0.74, 95% CI = 0.62–0.88, p = 0.001) and TFS (32.7 vs. 21.8 months, aHR = 0.74, 95% CI = 0.63–0.86, p < 0.001). Both OS and TFS did not differ between two groups in those with ADC. Conclusion: Real-world data indicated that pACT confers a survival benefit for resected ES-NSCLC patients with SCC but not ADC, which needs to be verified by a large sample of randomized controlled studies.