Adverse events with the use of radiotherapy in patients with inflammatory arthritides and cancer: A systematic review and meta-analysis.

e24090 Background: Radiotherapy is a cornerstone for multi-modality cancer treatment. However, there have been concerns that in patients with inflammatory arthritides (i.e., rheumatoid arthritis, juvenile idiopathic arthritis ankylosing spondylitis, Still’s disease) radiotherapy could result in deleterious outcomes, and radiation oncologists may be hesitant to administer radiation therapy to these patients. Methods: We conducted a systematic review to determine the risk of developing adverse events (AEs) from radiotherapy in patients with cancer and inflammatory arthritides. We searched in 4 electronic databases from inception through October 2022. Study selection, data collection and risk of bias assessment were independently performed by two investigators. We performed random-effects meta-analysis to determine the incidence of acute (≤ 90 days) and late ( > 90 days) AEs and evaluated the risk of developing AEs in these patients compared with cancer patients without inflammatory arthritides. Results: Out of 9,723 records retrieved from our searches, we included 7 cohort studies (5 included a control group) and 14 case reports (describing 22 patients). The age of the included patients ranged from 16-72 years. The median follow-up ranged from 1.5 to 12.5 years. Median radiation doses ranged from less than 40 Grays (exact doses not provided) to more than 60 Grays. The pooled incidence of acute AEs for patients with inflammatory arthritides when considering controlled and uncontrolled studies was 32% (95%CI 14%, 53%). When compared with controls (cancer patients receiving radiotherapy without inflammatory arthritides) no statistical difference was observed (Relative risk [RR] using only controlled studies 1.3; 95%CI 0.67, 2.5). For late AEs, the pooled incidence for patients with inflammatory arthritides when considering controlled and uncontrolled studies was 20% (95%CI 8%, 34%). However, the AEs in patients with inflammatory arthritides was significantly higher than that of controls (RR using only controlled studies 2.3; 95%CI 1.3, 4.3). The most common acute AEs reported were radiation dermatitis, gastrointestinal or genitourinary toxicity, and flares of the autoimmune disease. The most common late AEs reported were fibrosis, lymphedema, and pneumonitis. Out of the case reports, 5 patients reported late AEs and the remaining patients did not report AEs. Conclusions: While there were no differences in the frequency of acute AEs, patients with inflammatory arthritides had a statistically significant increased rate of late AEs compared with people without arthritides. Our results can assist in providing evidence-based information to patients with inflammatory arthritides considering radiotherapy.