Introduction: Usually, clinical trials on esophageal cancer exclude patients with a prior malignancy, assuming that this may influence survival outcomes. However, little is known about the impact of a prior malignancy on its prognosis.
Methodology: The Surveillance, Epidemiology, and End Results database (SEER) was used to review patients with stage IV squamous cell carcinoma (SCC) and adenocarcinoma (AC) of the esophagus during 1973-2014. We calculated overall and esophageal cancer-specific survival using unadjusted Kaplan-Meier and multivariable covariate-adjusted Cox models.
Results: A total of 7,807 patients with stage IV SCC, and 11,238 patients with stage IV AC were reviewed, of which 652 and 840 patients, respectively, had a prior malignancy. Kaplan-Meier curves did not show difference in overall survival of SCC or AC in patients with prior malignancy. Stage IV AC patients with prior malignancy did not show different esophageal cancer-specific survival. However, esophageal cancer-specific survival was better among stage IV SCC patients with prior malignancy. Similar results were observed in Cox models after adjustment for: age, sex, race, marital status, grade, site in esophagus, and undergoing surgery.
Conclusion: Prior malignancy does not adversely impact survival of stage IV esophageal cancer. These results should be taken into consideration when designing clinical trials.
Keywords: Esophageal neoplasms; clinical trials; survival analysis.