Optimal Duration of Preoperative Therapy in Unilateral and Nonmetastatic Wilms’ Tumor in Children Older Than 6 Months: Results of the Ninth International Society of Pediatric Oncology Wilms’ Tumor Trial and Study

PURPOSE: To determine the optimal duration of preoperative chemotherapy to further increase the proportion of stage I tumors by comparison of two regimens in the treatment of patients older than 6 months who have unilateral Wilms' tumor. PATIENTS AND METHODS: Eligible patients (n = 382) initially received four weekly doses of vincristine (VCR) and two courses of actinomycin D (AMD) and were randomized either to be operated on (4-week group n = 193) or to receive 4 more weeks of the same chemotherapy regimen (8-week group n = 189). The assessment criterion was the observed percentage of stage I tumors. After surgery, patients were assigned according to tumor stage and histology to four different treatment groups: stage I and favorable histology (n = 5) were to have no further treatment (NFT); stage I and standard histology or anaplasia (n = 244), VCR and AMD for 17 weeks (AV); stages II and III and favorable or standard histology, VCR, AMD, and an anthracycline for 27 weeks (AVE) with no abdominal radiotherapy for stage II N0 disease (n = 75) or with a 15-Gy dose of abdominal irradiation (RTH) in case of stages IIN1 and III (n = 56). Anaplastic tumors staged higher than I or clear-cell sarcoma of the kidney (14), AMD, VCR, an anthracycline, and ifosfamide for 36 weeks (DEVI). RESULTS: No advantage was found in favor of prolonged preoperative treatment. The percentages obtained for the 4-week and the 8-week groups, respectively, were as follows: stage I, 64% versus 62%; intraoperative tumor rupture rate, 1% versus 3%; 2-year EFS, 84% versus 83%; and 5-year OS, 92% versus 87%. Two-year EFS and 5-year OS rates, respectively, of the different treatment groups were as follows: NFT, 100% for both EFS and OS; AV, 88% and 93%; AVE, 84% and 88%; AVE RTH, 71% and 85%; and DEVI, 71% and 71%. The rate of abdominal recurrences in stage II N0 nonirradiated patients was 6.6%. CONCLUSION: The 4-week schedule pre-nephrectomy chemotherapy regimen should be considered the standard treatment. Clinical trials should continue to improve the cure rate of high-risk patients and the quality of life of children with a more favorable prognosis.