Similar to radiation-induced toxicity in head and neck cancers, single nucleotide polymorphisms of DNA repair and apoptosis genes may influence the severity of radiation-induced toxicity in RILI since data have confirmed involvement of ERCC1, ERCC5, TP53 and MDM2 in radiation-induced toxicity in head and neck cancer (68). The gene discussed is ERCC1; the disease is head and neck cancer.