Evaluation of the in vivo genotoxic effects of gamma radiation on the peripheral blood leukocytes of head and neck cancer patients undergoing radiotherapy

► We evaluated the in vivo genotoxic effects of γ-radiation on leucocytes of HNSCC. ► Genetic (molecular) damage was analyzed using the alkaline comet assay (SCGE). ► Recommend to reduce the daily radiotherapy dose for the safety of non-target cells. ► Cigarette smoking should be avoided during radiotherapy for better cure. ► SCGE is a sensitive method to screen human populations for biological dosimetry.