Abstract
AIMS: Autoimmune rheumatological diseases (ARDs) have historically represented an absolute or relative contraindication for radiotherapy (RT) due to increased RT-related toxicity and the potential exacerbation of rheumatologic disease. ARDs are more frequent in females (F:M 4:1). Breast cancer (BC) is the most common malignancy, accounting alone for 31% of female cancers. This study compared acute and late cutaneous toxicity in ARDs and non-ARDs population undergoing adjuvant breast RT. METHODS: Data of patients with BC and ARDs treated between 2013 and 2023 were retrospectively reviewed. The ARDs group was compared with a control group in a 1:2 ratio, homogeneous by age, type of treatment, RT total doses and fractionations, and target volumes' prescription. Acute and late toxicity were recorded using RTOG scales. RESULTS: We included 44 women with ARDs (median age 61 years) and 88 woman (median age 62 years) as control group. In ARDs group, the most used RT schedules were conventional fractionation (72.7%), while hypofractionation schedule (40-44 Gy) was administered in 12 patients (27.3%). In the control group, 64 patients (72.7%) received RT with conventional fractionation and 24 patients (27.3%) hypofractionation (40-44 Gy). Overall acute skin toxicity rate was 80.4% in the control group vs 86.4% in the ARDs group (p = 0.681). Specifically, G2 toxicity was 22.0% in the control group vs 31% in the ARDs group, while G3 acute toxicity was 2.3% in both groups. Overall late skin toxicity was 21.6% in the control group vs 27.3% in ARDs group (p = 0.067). Statistically significant difference was observed in late G2 toxicity with a 0% rate in the control group vs 6.8% in the experimental group (p = 0.035), respectively. CONCLUSIONS: ARDs do not seem to represent an absolute or relative contraindication in BC RT in terms of acute and late cutaneous toxicity. Hypofractionated schedule showed less toxicities in both group and, particularly, in ARDs group.