Cardiac death rates after irradiation for esophageal cancer: An epidemiologic study among esophageal cancer survivors.

Abstract

4049 Background: Esophageal cancer is frequently treated with radiation in addition to surgery and/or chemotherapy. Long-term survivors that received radiation may be at risk for radiation-induced cardiotoxicity. Methods: Esophageal cancer survivors (defined as surviving > 5 yrs after diagnosis) from all 18 Surveillance Epidemiology and End Results (SEER) registries from 1973 to 2013 were queried for irradiation status, cause of death and survival using SEERaBomb, a package for the R statistical programming language. Results: 6,514 esophageal cancer survivors were identified, of whom 2,892 (44%) received no radiation therapy and 3,448 (53%) received external beam radiotherapy. Mean age at the time of esophageal cancer diagnosis was 64.0 yrs in the no radiation group and 63.0 yrs in the radiation group. Median person years of follow up after esophageal cancer diagnosis was 8.6 yrs (interquartile range [IQR]: 7-12) in pts receiving no radiation and 7.9 yrs (6-11) in pts receiving radiation. A total of 590 esophageal cancer survivors died of cardiac disease; 254 received no radiation and 336 did receive radiation. Median time to cardiac death after esophageal cancer diagnosis was 32.2 yrs (IQR: 19-38) in pts that received no radiation and 25.3 years (15-30) in pts that received radiation (log-rank P< 0.001). Compared with unirradiated pts, irradiated pts had an increased risk of dying of cardiac disease (hazard ratio [HR] = 1.47; 95% confidence interval [CI]: 1.2-1.7, Cox regression P< 0.001). The association between radiation and cardiac death was the strongest in esophageal cancer pts diagnosed before 1995 (HR = 1.75; 95% CI: 1.4-2.2, P< 0.001) and in squamous cell carcinoma of the esophagus (HR = 1.9; 95% CI: 1.4-2.6, P< 0.001) but not in adenocarcinoma (HR = 1.04; 95% CI: 0.8-1.4, P= 0.8). Conclusions: 5-year esophageal cancer survivors that were treated with radiotherapy have an increased risk of dying of cardiac disease, compared with unirradiated counterparts. This association was strongest in pts treated before 1995 and in squamous cell carcinoma pts. This may be due to late radiation-induced cardiotoxicity, decreasing with the use of heart-sparing radiation techniques after 1995.