ObjectiveConcerns regarding offering radiotherapy to systemic sclerosis (SSc) patients stem from the potential worsening of SSc manifestations and radiotherapy toxicity. We conducted a systematic review to evaluate the effects of radiotherapy on SSc outcomes and radiotherapy-related toxicity.MethodsMEDLINE, Embase, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were searched for SSc and radiotherapy. Inclusion criteria were SSc diagnosis, subsequent cancer development, and radiotherapy exposure. Outcomes were SSc manifestations (cutaneous thickening, pulmonary fibrosis, and SSc flare) and radiotherapy toxicity (acute and late) utilizing Common Terminology Criteria for Adverse Events for grading. Grade 1 and 2 toxicities were categorized as non-severe and grade 3-5 as severe.ResultsOf 121 SSc patients undergoing radiotherapy (mean age 56.4 years, 83.3% female, median radiotherapy dose 50 Gy), most did not show worsened SSc skin thickening (92.7%) or pulmonary complications (90.3%) post-radiotherapy. In retrospective studies, the average rates of acute adverse effects were 57.3% for nonsevere and 25.8% for severe, while the rates of late adverse effects were 32.4% for non-severe and 24% for severe.ConclusionAlthough most SSc patients do not exhibit significant worsening of SSc manifestations post-radiotherapy, there is a variable risk of acute and late toxicity. These findings suggest that while radiotherapy may be a viable option for cancer patients with SSc, it requires caution.