[Prognosis of Wilm's tumor in the course of the SIOP trials and studies].

Wilms' tumor is the most common malignant renal tumor in children. Dramatic improvements in survival have occurred as the result of advances in anesthetic and surgical management, irradiation, and chemotherapy. Today treatments are based on several multicenter trials and studies conducted by the SIOP in Europe and NWTS in the USA. The main objectives of these trials and studies are to treat patients according to well-defined risk groups in order to achieve the highest cure rates, to decrease the frequency and intensity of acute and late toxicity, and to minimize the cost of therapy. The SIOP trials and studies largely focus on the issue of preoperative therapy whereas patients treated according to NWTS are primarily operated.