Effect of prior cancer history on survival of patients with esophageal carcinoma: a propensity score matching, population-based study.

Background: When conducting esophageal cancer clinical trials, prior cancer history is frequently considered an exclusion criterion due to the assumption that prior malignancy may exert significant interference with the prognosis in patients with esophageal carcinoma. This study aimed to evaluate the impact of prior cancer on survival of patients with esophageal cancer and provide valuable assistance for trial design. Methods: Data regarding patients diagnosed with esophageal cancer between 2011 and 2016 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database and divided into two groups depending on the presence or absence of prior cancer history. Propensity score matching (PSM) was performed to minimize the confounding bias caused by covariates. Subsequently, Kaplan-Meier analysis and multivariate Cox proportional hazards models were used to compare all-cause and esophageal cancer-specific survival between patients with and without prior cancer. Results: Among 17,123 patients with esophageal carcinoma included in this study, 2,224 (13%) patients had prior cancer history. Before PSM, Kaplan-Meier curves between the two groups classified by prior cancer history showed no significant differences in all-cause (HR =1.047, 95% CI: 0.995-1.102, P=0.077) and esophageal cancer-specific survival (HR =0.986, 95% CI: 0.928-1.048, P=0.65). Similar results were obtained after PSM. In multivariate Cox analysis, prior malignancy was not significantly associated with all-cause (HR =1.002, 95% CI: 0.936-1.072, P=0.965) and esophageal cancer-specific survival (HR =0.964, 95% CI: 0.890-1.045, P=0.374). Subgroup analysis stratified by timing of prior cancer demonstrated that prior cancer had no significant effect on prognosis in the recent latency period subgroups (P>0.05). Furthermore, patients with a prior cancer of lung and bronchus (P=0.013) or head and neck (P=0.012) displayed significantly worse survival than patients without prior cancer, while other types of prior cancer showed no significant effect. Conclusions: The findings suggest that prior cancer is likely not a definite factor that has an impact on all-cause and esophageal cancer-specific survival. Therefore, exclusion criteria of prior cancer history in esophageal cancer clinical trials should be seriously reconsidered.