Impact of rheumatoid arthritis on radiation-related toxicity and cosmesis in breast cancer patients: a contemporary matched-pair analysis

To evaluate the impact of rheumatoid arthritis (RA) on toxicity and cosmesis in women undergoing radiotherapy for breast cancer. We queried an institutional database for women with RA treated with external beam radiotherapy for breast cancer between 1981 and 2016. Matching each patient to three controls without RA was attempted. Radiation toxicity was graded using CTCAE 4.0. Cosmesis was graded using the Global Harris Scoring System of Excellent, Good, Fair, or Poor. Grade 2+ (G2+) acute and late toxicities were compared between women with RA and their matched pairs using a generalized estimating equation (GEE). Wilcoxon test and mixed effects model were used to compare the cosmesis between two groups. Forty women with RA at time of radiation were matched to 117 controls. The median radiation dose was 60 Gy (50-66 Gy) and the median follow-up was 94 months (1-354 months). When comparing the women with RA to their matched pairs, there was no significant difference in the rates of G2+ acute toxicity (25.0 vs. 13.7%, O 2.1, CI 0.91-4.9) or G2+ late toxicity (7.5 vs. 4.3%, OR 1.8, CI 0.48-6.8). Mean cosmesis was between Good and Excellent for both groups of patients, although women with RA were less likely to get Excellent cosmesis compared to their matched pairs (OR 0.35, CI 0.15-0.84). Among women with RA, radiation for breast cancer was well tolerated without significantly increased toxicity. Their cosmesis was generally Good to Excellent, although they might be less likely to get Excellent cosmesis compared to their matched pairs.