['To estimate the incidence and types of second neoplasms in survivors of childhood and adolescent cancer, as well as the characteristics of those who developed second neoplasms.', "Survivors who were under age 21 years at initial diagnosis, off therapy, and in remission for 2 years are referred to the Long Term Survivors' Clinic (LTSC) at Children's National Medical Center (CNMC). This review includes patients entered in the clinic database from January 1, 1997 to August 30, 2002.", 'Twenty-three (2.3%) of 987 childhood cancer survivors followed in the LTSC had 26 (2.6%) second and third neoplasms. The mean age was 6.7 years at initial diagnosis, 20.3 years at diagnosis of the second neoplasm, and 20.5 years at diagnosis of the third neoplasm. Of 10 female and 13 male patients, 15 were white, six black, one Hispanic, and one Asian. All but two of the patients received radiation. Nineteen neoplasms, including seven thyroid carcinomas, six central nervous system tumors (three meningiomas), three basal cell carcinomas, two breast cancers, and one soft tissue sarcoma, occurred at sites within or contiguous to radiation sites. Five patients died, but the majority of neoplasms were treatable and most patients had good outcomes.'] Are second neoplasms in survivors of childhood and adolescent cancer often treatable?