Using Real-world Historical Controls to Evaluate Radiation Dose Escalation in Esophageal Cancer

To the Editor Chen et al¹ are commended for reporting the final results of a phase 1/2, single-arm trial of chemoradiotherapy with a simultaneous integrated boost of radiotherapy dose as treatment for unresectable locally advanced esophageal cancer. The authors presented exploratory comparisons with an institutional cohort of 97 patients who received standard-dose radiotherapy and found that patients who received a simultaneous integrated boost of radiation had superior local control and overall survival. Although we appreciate the intention of using historical controls to augment evidence generated from single-arm trials, we note that such analyses and reporting require careful planning and rigorous disseminations.²