Abstract 4617: Association between DNA oxidative damage and radiotherapy-induced skin toxicities in breast cancer patients

Abstract

Abstract Background: Breast cancer is the most frequently diagnosed cancer and the second leading cause of cancer-related death in the female population in the United States. Although radiotherapy (RT) has been shown to improve prognosis in breast cancer patients, RT may also lead to side effects that impact overall quality of life in some patients. The objective of this study was to investigate whether an oxidative damage biomarker, 8-hydroxy-2-deoxyguanosine (8-OHdG), is associated with RT-induced early adverse skin reactions (EASRs) in breast cancer patients. Methods: 8-OHdG data before (pre-RT) and after RT (post-RT) were obtained from 475 breast cancer patients. RT-induced EASRs were assessed using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (v3.0) scale. Univariate logistic regression analyses were conducted to evaluate associations between above-median 8-OHdG (> 85 ng/ml) and RT-induced grade 2+ EASRs. A propensity score (PS) was derived from a logistic regression model for predicting RT-induced EASRs on the basis of patient, tumor, and treatment characteristics. Then, the association between 8-OHdG and RT-induced EASRs was assessed in four risk groups defined by quartiles of PS. Results: Overall, 59% of patients developed RT-induced grade 2+ EASRs and 28% developed moist desquamation. There were no significant associations between RT-induced EASRs and high 8-OHdG levels at both pre-RT and post-RT. However, there was a significant association between patients in the 2nd quartile PS that had high post-RT 8-OHdG levels and grade 2+ EASRs (OR=2.51, 95%CI=1.17, 5.40, p=0.0183). Conclusions: The results from this study suggest that 8-OHdG is a potential biomarker for RT-induced EASRs in a breast cancer population with low to medium (2nd quartile) propensity for RT-induced EASRs. Citation Format: Moody M. Mihyu, Isildinha M. Reis, Cristiane Takita, Jean L. Wright, Eunkyung Lee, Omar L. Nelson, George R. Yang, Johnna L. Bakalar, Jennifer J. Hu. Association between DNA oxidative damage and radiotherapy-induced skin toxicities in breast cancer patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4617.