Genetic Susceptibility to Radiation-Induced Skin Reactions in Racial/Ethnic Groups of Patients With Breast Cancer

Overview

RATIONALE: Radiation therapy uses high-energy x rays to kill tumor cells. Radiation therapy may cause skin reactions when patients are exposed to high-energy x rays. Studying the genetic pattern of patients before and after radiation therapy may help doctors prevent toxicity and plan the best treatment. PURPOSE: This clinical trial studies genetic susceptibility to radiation-induced skin reactions in racial/ethnic groups of patients with breast cancer.

OBJECTIVES: * To develop and validate prediction biomarkers for radiation therapy (RT)-induced acute and chronic skin reactions and quality of life in five racial/ethnic groups of breast cancer patients, Whites\*, Black/African Americans, Hispanic/Latinos, Asians/Native Hawaiians/Pacific Islanders, and American Indians/Alaskan Natives. NOTE: \*This stratum is closed as of April 25, 2012. * To develop polygenic models of RT-induced skin reactions with a comprehensive evaluation of genome-wide nonsynonymous single nucleotide polymorphisms (nsSNPs). * To evaluate the levels of DNA damage (Comet assay) and radiosensitivity (Cell Cycle G2 Delay assay) in lymphocytes before and after RT. * To test the effect of gene-gene and gene-smoking interactions on RT-induced skin reactions. * To assess race-ethnic differences in RT-induced skin reactions, DNA damage, and radiosensitivity and to determine if the gene effects are consistent across race-ethnicity (gene-race/ethnic interactions). OUTLINE: This is a multicenter study. Patients are stratified according to race/ethnicity (Whites\* vs Black/African Americans vs Hispanic/Latinos vs Asians/Native Hawaiians/Pacific Islanders vs American Indians/Alaskan Natives). NOTE: \*This stratum is closed as of April 25, 2012. Patients undergo adjuvant radiotherapy after breast-conserving surgery. Blood and urine samples are collected at baseline and last day of radiotherapy for genotyping, DNA damage, cell cycle assays, urine cotinine, inflammatory immune response biomarkers, and tumor-killing activity by BeadArray System, Comet assay, flow cytometry-based assay, Cell-Cycle G2 Delay Assay, Oxygen Radical Absorbance Capacity (ORAC) assay, and ELISA. Patients are assessed for acute toxicity by research staff using the ONS Criteria for Radiation-Induced Acute Skin Toxicity at baseline, week 3, and at 1 and 2 months after radiotherapy. Patients are also assessed for chronic toxicity by research staff using the Chronic skin toxicity questionnaire (RTOG SOMA Criteria for RT- Induced Breast/Chest Wall Late Skin Toxicity) at 6 and 12 months after completion of radiotherapy. Photographs of the breast, chest wall, and contralateral breast are also taken at baseline, week 3, last day of radiotherapy, and at 1, 2, 6, and 12 months after completion of radiotherapy. Patients complete the Breast Cancer Risk Study Questionnaire, the Functional Assessment of Cancer Therapy Breast (FACT-B), the Modified Skindex, and the B39 Quality-of-Life (QOL) Questionnaire at baseline, last day of radiotherapy, and at 1, 2, 6, and 12 months after radiotherapy.