Assessment of Toxic Effects Associated With Dose-Fractionated Radiotherapy Among Patients With Cancer and Comorbid Collagen Vascular Disease

Key Points Question Is dose-fractionation associated with the incidence of toxic effects among patients with cancer and comorbid collagen vascular disease? Findings In this cohort study of 197 adults with cancer and comorbid collagen vascular disease, the incidence of severe toxic effects was similar across multiple dose-fractionated radiotherapy regimens, including conventionally fractionated, moderately hypofractionated, and ultrahypofractionated radiotherapy; the unadjusted incidence of severe acute toxic effects was 5%, 7%, and 2%, respectively, while the unadjusted incidence of severe late toxic effects was 8%, 0%, and 2%, respectively. The receipt of hypofractionated radiotherapy was associated with a lower likelihood of developing late toxic effects in the multivariable analysis. Meaning This study found that the incidence of severe toxic effects among patients with cancer and comorbid collagen vascular disease was similar across several dose-fractionated radiotherapy regimens.