Association of Chemoradiotherapy With Thoracic Vertebral Fractures in Patients With Esophageal Cancer

IMPORTANCE: The association of chemoradiotherapy (CRT) with a thoracic vertebral fracture in patients with esophageal cancer is unknown. OBJECTIVE: To determine whether CRT is associated with thoracic vertebral fractures in patients with esophageal cancer. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study included patients with clinical stages I to III thoracic esophageal cancer who visited the Kyoto University Hospital, Kyoto, Japan, from January 1, 2007, to December 31, 2013. Data were analyzed from April 6, 2018, to June 4, 2020. EXPOSURES: Chemoradiotherapy (CRT group) or surgery or endoscopic treatment (non-CRT group). MAIN OUTCOMES AND MEASURES: The main outcome of this study was the cumulative incidence rate of thoracic vertebral fractures in 36 months. The incidence rate was calculated taking censoring into account. Possible risk factors, including CRT, were explored in the multivariable analysis. The association of irradiated doses with fractured vertebrae was also evaluated. RESULTS: A total of 315 patients (119 for the CRT group and 196 for the non-CRT group) were included. The median age of patients was 65 (range, 32-85) years. Fifty-six patients (17.8%) were female and 259 (82.2%) were male. The median observation time was 40.4 (range, 0.7-124.1) months. Thoracic vertebral fractures were observed in 20 patients (16.8%) in the CRT group and 8 patients (4.1%) in the non-CRT group. The 36-month incidence rate of thoracic vertebral fractures was 12.3% (95% CI, 7.0%-19.1%) in the CRT group and 3.5% (95% CI, 1.3%-7.5%) in the non-CRT group (hazard ratio [HR], 3.41 [95% CI, 1.50-7.73]; P = .003). The multivariable analysis showed that the HR of the thoracic vertebral fracture in the CRT group to non-CRT group was 3.91 (95% CI, 1.66-9.23; P = .002) with adjusting for sex, 3.14 (95% CI, 1.37-7.19; P = .007) with adjusting for age, and 3.10 (95% CI, 1.33-7.24; P = .009) with adjusting for the history of vertebral or hip fractures. The HR of the thoracic vertebral fracture for a 5-Gy increase in the mean radiation dose to the single vertebra was 1.19 (95% CI, 1.04-1.36; P = .009). CONCLUSIONS AND RELEVANCE: This study found that chemoradiotherapy was associated with thoracic vertebral fractures in patients with esophageal cancers. A reduced radiation dose to thoracic vertebrae may decrease the incidence of fractures.