Abstract 3920: Polymorphisms of DNA-repair pathways and its association with radiotherapy-induced acute skin toxicity among tri-racial breast cancer populations

Abstract

Abstract Radiotherapy-induced skin toxicity is one of the critical quality of life issues in breast cancer patients receiving adjuvant radiation therapy (RT). Finding a biomarker which can predict the development of acute RT-induced toxicity prior to RT is critical to improve precision medicine in radiation oncology. This study evaluated the association of single nucleotide polymorphisms (SNPs) in DNA-repair genes in 268 breast cancer undergoing adjuvant RT. We analyzed 3,747 polymorphisms in 119 DNA repair-related genes; 15 genes in base excision repair (BER), 11 in mismatch repair (MMR), 26 in nucleotide excision repair (NER), 15 in homologous recombination, 5 in non-homologous end-joining (NHEJ), 15 in DNA polymerases, and 47 in other DNA repair-related pathways. Skin toxicity was assessed at post-RT using the modified NCI's Common Toxicity Criteria for Adverse Events (CTCAE) and multiple logistic regression analyses were conducted to assess the associations between SNPs and grade ≥ 4 skin toxicity n = 115). After controlling for covariates, 221 SNPs were significant at p <0.05 and 34 at p < 0.01. Significant associations (p<0.01) were found in 7 SNPs in PAPD5 gene, 1 in POLD1, POLE, and POLI in DNA polymerase; 5 in RAD51L1 and 1 in RAD54L in HR; 4 in MMS19 in NER; 2 in MSH4 and 1 in PMS1 in MMR; 2 in RPA3 in BER; 2 in RAD18, and 1 in UBE2V2 in Rad6 pathway; 2 in CHEK2 in DNA damage response pathway; 1 in MGMT in direct reversal of DNA damage; and 1 in BLM in diseases associated with sensitivity to DNA damaging agents pathways. Among these, most significant association was found in BLM variant (s16944918) which showed that carrying at least one minor T allele was associated with increased risk of RT-induced skin toxicity (odds ratio [OR] = 3.36; 95% confidence interval (CI) = 1.62-6.97, p = 0.001). For RPA3 (rs11978293), carriers with at least one minor G allele were more likely to develop RT-induced skin toxicity (OR = 2.17, 95% CI = 1.34-3.52, p = 0.002). The current study suggests that genetic variations in multiple DNA-repair genes/pathways may contribute to inter-individual variation in RT-induced normal tissue toxicity in breast cancer patients and suggests the possibility of potential predictive values of genetic polymorphisms in RT sensitivity. Further validation studies with larger sample size are warranted. Citation Format: Sung Yong Eum, Eunkyung Lee, Jean L. Wright, Christiane Takita, Eden R, Martin, Susan Slifer, Jennifer J. Hu. Polymorphisms of DNA-repair pathways and its association with radiotherapy-induced acute skin toxicity among tri-racial breast cancer populations. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3920.