PROBLEM TO BE SOLVED: To provide a medicine for treating cancer of a patient. A drug for treating cancer in a patient in need of treatment by combining a therapeutic effective dose of radiation and a therapeutically effective amount of a chemotherapeutic agent, and providing an effective amount of cerium oxide nanoparticles (CONP). Drugs that include, the cancer is pancreatic cancer, lung cancer, breast cancer, ovarian cancer, head and neck cancer, and / or colon cancer. [Selection diagram] Fig. 1【課題】患者のがんの治療のための医薬の提供。【解決手段】治療を必要とする患者におけるがんを治療実効線量の放射線及び治療的有効量の化学療法剤を組合せて治療するための医薬であって、有効量の酸化セリウムナノ粒子（ＣＯＮＰ）を含み、がんが、膵臓がん、肺がん、乳がん、卵巣がん、頭頸部がん、及び／又は大腸がんである、医薬。【選択図】図１
