Radiation therapy in the neonate.

Radiation therapy (RT) is frequently used in the management of children with cancer, but neonatal neoplasms are rare. Newborns represent 1.5% of the children with malignant diseases in the Tumor Registry at the Children's Hospital of Philadelphia over the last 30 years. Thus, occasionally the pediatrics radiation therapist must consider treating the very young infant. The specific radiation effects on growth and development must be weighed in reaching a therapeutic decision. All children are vulnerable to the late effects of radiation therapy, but the neonates may be more susceptible because of the immaturity of important organs such as the brain, lung, liver, kidney, and bone. In general, radiation therapy, should be avoided during the first several weeks of life because of the potential increased sensitivity of the liver and kidneys during that period. If radiation therapy is used at all during infancy, the benefits must be weighed against the possibility of significant late effects. Increasing knowledge of pediatric neoplasms has shown that some tumors (such as mesoblastic nephroma) require no treatment except for surgical excision; and other tumors, such as Stage IV-S neuroblastoma, may require very little treatment. In those tumors that require radiation therapy, the use of chemotherapy may allow reduction of the radiation dose. Furthermore, alterations of time-dose-fractionation schemes and careful attention to tumor volume with the use of special techniques, such as "shrinking fields," may decrease the late adverse effects of treatment.