Aos Aboabat1, Mohammed AlDohan2, Patrick Cheung2, Ani Orchanian-Cheff3 and Sindhu Johnson4, 1University of Toronto, Toronto, ON, Canada, 2Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 3Library and Information Services, University Health Network, Toronto, ON, Canada, 4Division of Rheumatology, Department of Medicine, Schroeder Arthritis Institute, Krembil Research Institute, Toronto Western and Mount Sinai Hospitals; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada
Background/Purpose: Systemic sclerosis (SSc) is a chronic autoimmune disorder with higher risks of malignancies. Concerns regarding offering radiotherapy (RT) to SSc patients stem from the potential to worsen SSc manifestations and RT-specific toxicity. Through systematic review of the literature, we evaluated the effect of RT on SSc-manifestations and RT-specific adverse
Methods: MEDLINE, Embase, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials were searched using subject headings and text words for systemic sclerosis and RT. Inclusion criteria were a physician-based diagnosis of SSc, development of cancer after SSc diagnosis, and exposure to RT. The outcomes were SSc manifestations (cutaneous thickening by mRSS or physicians' clinical assessment, pulmonary fibrosis, flare of SSc) and RT-related toxicity (acute and late).
Results: The search yielded 25 articles, comprising 12 case reports, 3 case series, 5 retrospective cohort studies, and 5 case-control studies. A total of 121 SSc patients who received RT were included, with a mean age of 54.9 years, and 73.6% were female. Indications for RT were breast (N = 46), intrathoracic (N = 7), head and neck (N = 4), genitourinary (N = 3), colorectal (N = 3), and central nervous system (N = 1) cancers. The intent of RT was curative (88.7%) and (11.3% palliative. Post-RT 36/39 (92.3%) did not develop worsening skin thickening, 1/39 (2.6%) had minimal worsening of skin thickening and 2/39 (5.1%) had progressive skin thickening beyond the radiation port. Following RT, 36/39 (92.3%) did not develop SSc-related pulmonary complications, 1/39 (2.6%) developed pulmonary fibrosis, and 1/39 (2.6%) diffuse alveolar hemorrhage. Acute RT adverse effects were reported in 57 patients, with severe acute adverse events observed in a minority. Late non-severe RT adverse effects (Grade 1 and 2 toxicities) included seromas and telangiectasias, whereas late severe adverse effects (Grade 3- 5) included dysphagia, laryngeal edema, radiation pneumonitis, esophageal stricture and small-bowel obstruction. The frequency of grade 3-5 toxicity in cohort studies ranged between 15%-24%.
Conclusion: The majority of SSc patients did not develop worsening SSc-related manifestations following RT, suggesting that RT can be safely administered. A minority experienced acute severe RT-related adverse effects. However, the risk of severe late RT-related adverse effects may be high, underlining the need for close follow-up during and after RT. A larger prospective controlled study is needed to confirm these findings and to identify potential risk factors for adverse outcomes in SSc patients undergoing RT.
A. Aboabat: None; M. AlDohan: None; P. Cheung: None; A. Orchanian-Cheff: None; S. Johnson: None.