Partial nephrectomy for unilateral Wilms tumor: Results of study SIOP 93-01/GPOH

Purpose: We evaluate results and long-term outcome after partial nephrectomy (PN) for unilateral Wilms tumor (ulWT) in relation to different histological features, performed as initial surgery or after induction chemotherapy (ChT). Materials and Methods: Data from patients with ulWT who had undergone PN in the German Study SIOP 93-01/GPOH were analyzed for time of surgery in the treatment schedule, postoperative stage, histological features, surgical radicality and outcome. The results were correlated with overall survival and relapse-free survival, and compared with those of patients who had undergone total tumor nephrectomy (TN). Results: A total of 770 patients underwent TN and 37 underwent PN, of which 766 (99.5%) and 36 (97.3%), respectively, were radical procedures. A total of 139 TNs and 15 PNs were performed at primary surgery, 630 TNs and 22 PNs after ChT, and 1 TN after irradiation. Two of 15 patients following primary PN and 1 of 22 following delayed PN had local recurrence. Two patients died of metastatic disease. Tumor stage, overall survival of 93% and relapse-free survival of 88% were equal after PN and TN in analysis of the whole group. This was also true for patients with surgery after ChT. One of 2 patients with histologically unfavorable disease had relapse after PN compared to only 3 of 35 patients with histologically low or intermediate risk disease. Conclusions: PN should be performed only for small, histologically low or intermediate risk tumors after good response to ChT to secure a complete resection.