Abstract
BACKGROUND: To estimate the adjusted conditional overall survival (COS) in patients with esophageal cancer after receiving various treatment modalities via a national population-based database, and to investigate the possible time-dependent effects. MATERIALS AND METHODS: Eligible patients diagnosed with esophageal cancer between 2000 and 2016 were identified from the Surveillance, Epidemiology, and End Results (SEER) registry. The Kaplan-Meier method was used to calculate conventional survival time. The inverse probability of treatment weighting method was used to estimate the adjusted COS in patients receiving different treatment modalities. Landmark analysis was employed to investigate the possible time-dependent effects of different treatment modalities in patients who had survived a certain period of time. RESULTS: A total of 25,232 patients were included in the final analysis. The conventional 5-year overall survival was 19.3%. The 5-year adjusted COS increased most for the first 3 years, and increased slightly afterwards. In patients with regional esophageal or gastroesophageal junction cancer, stage-specific analysis showed that surgery only and preoperative radiation therapy benefited most for patients with localized disease, preoperative radiation therapy plus surgery benefited regional, and preoperative radiation therapy plus surgery benefited distant disease, with the 5-year adjusted COS given patients had survived 3 years being 67.0% (95% CI 65.2%-68.7%), 59.9% (95% CI 58.3%-61.5%), 58.4% (95% CI 56.3%-60.5%), and 61.8% (95% CI 59.5%-64.1%), respectively. In time-dependent analysis, the benefits of surgery only in localized cases were prominent within 48 months after diagnosis. Preoperative radiation therapy showed long-lasting benefits in patients with regional disease. In patients with distant disease, all treatment modalities showed similar and short-term effects. CONCLUSIONS: The adjusted COS in patients with esophageal cancer increased as time accrued after receiving various treatment modalities. The time-dependent effects in specific tumor stage provided a dynamic view on optimization of treatment strategies.