Wilms' tumor 1991. Clinical evaluation and treatment.

Wilms' tumor is the most common malignant tumor of the kidney in children. Although only 500 cases per year are diagnosed in the US, the tumor has been studied extensively in the National Wilms' Tumor Committee Cooperative Studies. These prospective studies have led to improved survival and at the same time reduced treatment and complications in the more favorable cases. Similar results have been shown by the European cooperative study group SIOP using different treatment protocols. These studies have identified a group of tumors with unfavorable histology that are more resistant to treatment and will require more intensive protocols. Diagnosis of Wilms' tumor by the finding of a large flank mass in an otherwise healthy-appearing child is usually easy. Imaging techniques of CT or IVU will give accurate confirmation of Wilms' tumor in 95% of children. Modern treatment in the US by radical nephrectomy followed by chemotherapy with or without radiotherapy depends on tumor stage and histology. Early-stage tumors with favorable histology can be controlled by shorter courses of two-drug treatment (dactinomycin and vincristine) without radiation. Advanced tumors respond to treatment but require more intensive chemotherapy combined with radiation. The final challenge is the child with a tumor of unfavorable histology, particularly if there is advanced-stage disease. Whereas Wilms' tumor showing favorable histology now has a survival rate exceeding 90%, survival of those with tumors of unfavorable histology remains poor. The European (SIOP) studies have shown similar survival figures using preoperative chemotherapy. This technique produces shrinkage of tumors, making them less hemorrhagic and producing a lower incidence of rupture at subsequent surgery. Preoperative chemotherapy does not change the histologic diagnosis of Wilms' tumor and is a useful alternative approach for the large hemorrhagic or infiltrating tumors.