Use of genotoxicity, oxidative stress and inflammation blood biomarkers to predict the occurence of late cutaneous side effects after radiotherapy in Merkel cell carcinomas patients

Abstract : Despite the technical advances in radiotherapy, toxicity to healthy tissues remains the limiting factor of treatment. The aim of this work is to highlight one or more blood markers whose ex vivo variations after irradiation (IR) could predict the occurrence of late cutaneous side effects. For this preliminary study, we selected patients with Merkel cell carcinoma (MCC) because, although rare, their treatment only includes radiotherapy and the dosimetry data are accurate to the skin. Two groups of patients were established according to the grade of late cutaneous toxicity after adjuvant IR for MCC: (i) no or little toxicity (grade 0, 1 or 2 of the RTOG), (ii) marked toxicity (grade 3 or 4 of the RTOG). In order to try to discriminate these 2 groups, markers of interest were selected and measured on the different compartments of ex vivo irradiated blood. At the lymphocyte level, cell cycle and apoptosis (flow cytometry) and genotoxicity (micronuclei) were quantified.