The Advantages of Preoperative Therapy in Wilms' Tumour*

: During 1971-1980, three consecutive clinical studies on nephroblastoma were conducted by the International Society of Paediatric Oncology (SIOP). Besides several questions on different postoperative treatment modalities, the emphasis of these trials was to determine the role of preoperative therapy. In SIOP-1 (1971-1974) we compared preoperative radiotherapy to immediate surgery. There is no difference in survival or recurrence-free survival between both groups. Tumour ruptures, however, did occur significantly less in the pretreated group, and the recurrence-free survival is clearly lower in patients with intraoperative tumour rupture. These results were confirmed by SIOP-2, a non-randomised study conducted between 1974 and 1976. The question tackled by SIOP-5 (1977-1980) was whether preoperative chemotherapy could be a substitute for preoperative radiotherapy. The two preoperative therapies produced equally satisfactory results in terms of recurrence-free survival and 4-year survival rates, and the reduction in the number of operative ruptures. In addition, it was shown that with preoperative chemotherapy about 45% of an unselected population of patients with Wilms' tumour can be treated and cured without any irradiation and its well-known sequelae. The actual need for radiotherapy in stage II tumours with negative lymph node involvement (about 30% of the patients after pretreatment) is under investigation in SIOP-6. Cytohistological grading is equally possible after chemotherapy, and also without pretreatment. If antitumour treatment is begun before histopathological diagnosis, then the risk of overtreating patients with benign conditions, or of administering an inappropriate treatment to patients with malignant tumours of other types, is about 6%.(ABSTRACT TRUNCATED AT 250 WORDS)