Factors responsible for stage III disease in patients with Wilms tumor enrolled in the JWiTS-2 study

Background/objectives Treatment is more intensive for stage III Wilms tumor (WT) than for stages I and II non-metastatic WTs. Various factors including tumor spillage, unresectability, and lymph node metastasis are responsible for stage III disease. The present study aimed to not identify clinical factors associated with the features of stage III WT to establish new treatment strategies. Design/methods Of 166 patients with non-metastatic WT enrolled in the Japan Wilms Tumor Study (JWiTS)-2, 51 patients had stage III disease. The treatment protocol for JWiTS-2 was essentially the same as that in the National Wilms Tumor study (NWTS)-5. Local hospitals were surveyed to collect details of clinical findings related to stage III disease, and data regarding 45 (88%) patients were obtained. Results Nine patients with massive tumors underwent preoperative chemotherapy. Biopsy was performed in 6. Reduction in the tumor size was achieved in 8 of the 9 cases. Nephrectomy was finally performed in all of them. Thirty-six patients underwent primary nephrectomy. The reason for the stage III disease was lymph node metastasis ( n = 9, 25%), tumor spillage ( n = 20, 56%), and tumor extension/incomplete resection ( n = 17, 47%). Some patients had more than one of these factors. Most patients were treated with the DD-4A regimen, and 43 (95.6%) of the 45 patients received abdominal radiation therapy. Tumors recurred in three patients (local, 1; metastasis, 2), and two patients died. Overall and relapse-free survival rates were 95.2% and 90.8%, respectively. Conclusion The prognosis of stage III WT was good. In the next stage, the doses of chemotherapy and radiotherapy should be reduced to avoid late effects. The high rate of tumor spillage after primary resection suggests that preoperative chemotherapy should be started instead of aggressive tumor resection in the large tumor cases with surgical risks