Principles of treatment of pediatric solid tumors. Great strides have been made in the treatment of pediatric solid tumors over the last three decades. A multimodality approach involving a combination of surgery, radiation therapy, and chemotherapy is now used in the treatment of these diseases. This article reviews the principles that guide the use of these modalities and the multidisciplinary approach used to integrate them into a coordinated treatment plan. The role of each modality in the control of local and systemic disease is described. Radiation treatment planning, dose fractionation, and toxicity are also discussed. 