The incidence of clinical adverse events (CAEs: xerophthalmia, xerostomia, and dysgeusia) and values for hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs) and platelets (PLTs) during the first year of follow-up were compared between patients who underwent standard-dose RAI (SDRAI) therapy and LDRAI therapy. This evidence concerns the gene GSTM1 and xerostomia.