[Importance of Secondary Cancer Screening-In the Case of Childhood Cancer].

The cumulative incidence of secondary cancers in childhood cancer survivors at 20 years after treatment is 2-5%, which is 3-20 times higher than in the general population. Risk factors include radiation therapy, alkylating agents, platinum drugs, and topoisomerase Ⅱ inhibitors. A retrospective cohort study of 15 pediatric oncology hospitals in Japan revealed that the time to development of a second cancer varies from 5 years or less for hematologic tumors, 10 years or less for bone/soft tissue tumors, approximately 10 years for brain tumors, and 15-20 years for thyroid and adult-type cancers. Some secondary cancers have a poor prognosis. Primary prevention of secondary cancers is the same as in the general population, and early detection and treatment are important. The key points of consensus on secondary cancers by the North American Children's Oncology Group guidelines and the International Guideline Harmonization Group were presented. In the future, it will be important to share information on the benefits and risks of cancer screening with childhood cancer survivors and their families.