Second tumors after treatment of childhood malignancies.

The occurrence of a second malignancy represents a serious complication of childhood cancer. With the introduction of more intensive multiagent therapy for childhood cancers, not only are a greater proportion of children surviving their initial cancer, but also they now may be at greater risk for developing a second malignancy. The larger studies indicate that the cumulative incidence of second cancers may be as high as 12% at 20 years following the initial cancer. The most consistent finding of the larger studies is that the elevated risk of a second cancer remains relatively constant over time, but the absolute risk increases substantially as the length of follow-up increases. There are treatment-related risk factors, such as solid tumors within irradiated fields and secondary leukemias following alkylating therapy. Retinoblastoma represents one example of the role of genetic predisposition in second cancers. It is imperative that survivors of childhood cancer be closely followed to determine the occurrence of second cancers, particularly those that may occur many years following the original childhood cancer. Research needs to be directed toward the identification of treatment, as well as genetic and life style risk factors. Intervention, through modifications of treatment protocols and implementation of preventive programs, may have a future role in reducing the occurrence of second cancers.