Brachytherapy for solid tumors in children.

ABSTRACT

The standard treatment after surgery and chemotherapy in pediatric solid tumors is external beam to the tumor with a generous (5 cm) margin for local control. This treatment is given over a five to six-week period, requires use of repeated deep sedation, and leads to unacceptable morbidity (especially organ and bone-growth retardation) in infants and younger children. Limited volume irradiation by brachytherapy over a few days may be sufficient therapy for children treated with aggressive chemotherapy. Brachytherapy allows high doses of radiation to be limited accurately to the tumor bed, spares the surrounding normal tissues, and thus minimizes late sequelae. Manually afterloaded removable iridium-192, iodine-125, and cesium-137 have been used with good results. The major disadvantages of LDR brachytherapy are the necessary sedation and immobilization of younger children to prevent accidental removal of the implants during the entire period, radiation exposure to the medical personnel and the parents, and the psychological effect of separating parents from their child. Using a low energy radionuclide such as iodine-125, or remote afterloading technology with LDR and PDR reduces radiation exposure hazards, but prolonged sedation and immobilization are still required. HDR brachytherapy not only eliminates the radiation exposure hazards but, in addition, eliminates the other disadvantages of brachytherapy thereby extending treatment to the infants and younger children. The long term effects of brachytherapy need further study.