REB investigators are collaborating with extramural investigators in a follow-up study of 14,000 long-term childhood cancers. Outcomes being evaluated include second and subsequent cancers, reproductive, psychosocial, and a wide range of chronic disease outcomes. The survivors completed a detailed questoinnaire that included questions on the above outcomes as well as detailed family history of cancer. Periodic follow-up questionnaires are being sent to update information on occurrence of second malignancies. DNA samples are being requested from all members of the cohort. As a comparison group, the siblings of all cohort members were asked to complete the long earlier questionnaire. The initial cohort included childhood cancer patients diagnosed between 1970 and 1986. The cohort is now being expanded to include patients diagnosed between 1987 and 1999. Priority areas for DCEG research include quantifying radiation dose-response relations and genomics of late effects.