Nuclear medicine in pediatric oncology.

Pediatric malignancies are relatively rare and account for 0.5% of all cancers. The annual incidence varies between 110 and 150 per million children, which means that the chance for a child to develop a cancer during the first 15 years of life is 1:450–600. Leukemias and tumors of the brain and spinal cord have the highest relative incidence rates, followed in frequency by neuroblastoma, lymphomas, Wilms tumor and bone tumors. Other tumor types are less frequent. Pediatric tumors arise as a result of disturbance of genetic material. In very young children predominantly blastemal tumors (e.g. nephroblastoma, neuroblastoma, medulloblastoma) occur, whereas in the age group 10–25 years sarcoma’s (e.g. osteosarcoma, EWING sarcoma) are dominating. Carcinomas are typically adult-type tumors (> 30 years of age). The overall survival rate for childhood cancers has improved significantly over the years (from 25% in the 1960’s to 75% in the 1990’s). This means that the pool of children and adults, who have survived childhood cancer and who are in follow up and being studied for potential late effects, is continuously increasing [1]. In recent years the contribution of nuclear medicine has been of increasing interest to pediatric oncology, in particular in imaging for diagnosis, staging and follow-up, in quantitative function analysis of organs at risk during oncological therapy, as well as in radionuclide therapy [2–5]. Nuclear medicine studies in children require special considerations regarding the performance of the procedure and the attitude of the attending staff [6]. In tumor imaging the trend has been to use more or less specific tumor-seeking radiopharmaceuticals. A great number of these agents are available, exploiting various metabolic and biological properties of individual tumors. Parallel to these developments radionuclide therapy becomes more widely used, whenever its success is envisaged on the basis of a good and selective uptake and long retention of the radiopharmaceutical in the tumor. Table 1 shows a list of tumor seeking radiopharmaceuticals, which are currently available for diagnosis and therapy of pediatric tumors. The major indications, in which nuclear medicine has a role, are discussed below.