In some subgroups, cyclin D1 gene CCND1 rs9344 and inhibitor of κB kinase gene IKBKB rs12676482 were related with the grade 3–4 acute radiation-induced myelosuppression, and CCND1 rs9344 was also associated with grade 3–4 acute radiation-induced oral mucositis. The gene discussed is IKBKB; the disease is oral mucositis.