Is partial nephrectomy appropriate treatment for unilateral Wilms' tumor?

PURPOSE: After nephrectomy for unilateral Wilms' tumor (WT), two potential hazards threaten the remaining kidney. The development of a metachronous WT (2% to 3%), and decrease in renal function after chemotherapy. Our study aims included: (1) to clarify how many WT patients could benefit from partial nephrectomy (PN) without jeopardizing the high cure rate, (2) to establish the function of the kidney remnant, and (3) to test the radiological criteria for preoperative selection of PN candidates.
METHODS: A retrospective analysis of 90 consecutive cases of histologically verified WT (1982 to 1992) was carried out. Data were studied independently by the surgeon, the radiologist, and the pathologist. The preoperative selection criteria for PN were functioning kidney, tumor confined to upper or lower pole leaving two thirds of the kidney tumor free, and no hilar or vascular structures involved. After PN, renal function was estimated by a calculated creatinine clearance (CC) combined with the assessment of the relative function of each kidney by renal scintigraphy.
RESULTS: There were 46 boys and 44 girls with median age at diagnosis of 3 years 6 months (range, 3 months to 16 years 7 months). Stage I disease occurred in 40 patients, stage II in 23, stage III in 16, and stage IV occurred in 11 patients. Nearly all patients received preoperative chemotherapy. Radiological analysis of 85 available data sets (5 missing) suggested that PN was possible in 13 patients, and data were inconclusive in two. All 13 patients selected by the radiologist appeared to be in agreement with the pathological criteria for resectability. Of these cases, complete resection by PN was performed in five, could have been possible in retrospect in two, and appeared impossible in six. In two more patients, PN was performed; in both cases the radiologist had predicted PN to be impossible. Median follow-up after PN was 61 months, range, 45 to 167 months. Two patients died of distant metastasis, and no local recurrence occurred. Five are in remission with a median CC level of 110 mL/min, range, 85 to 124. Relative functions of the kidney remnants were 20% to 50%. Contralateral nephrectomy for progressive obstruction was performed in one, but CC level remained normal (85 mL/min). Comparing the preoperative radiological prediction with the combined surgical and pathological findings in a 2 x 2 frequency table, the sensitivity of the radiological findings could be calculated to be 80%, the specificity 97%, and the accuracy 87%.
CONCLUSIONS: (1) Partial nephrectomy is safe in approximately 10% of Wilms' tumor patients. (2) The function of the kidney remnant remains well, and even permits contralateral nephrectomy. (3) Preoperative imaging shows an accuracy of 87% to predict the possibility for partial nephrectomy.