The relationship between the site of metastases and outcome in children with stage IV Wilms Tumor: data from 3 European Pediatric Cancer Institutions.

The aim of this study was to analyze in detail the site of metastasis of stage 4 Wilms tumor (WT) and its correlation with outcome. The databases from 3 major European pediatric cancer institutions were screened for children with WT between 1994 and 2011. Of 208 children identified, 31 (14.9%) had metastases at diagnosis. The lung was affected in 29 children (93.5%) and the liver in 6 children (19.4%). Twenty-seven children (87.1%) had metastases isolated to 1 organ, with the lung being the most common site (80.7%). Five-year overall survival was significantly better in those children with distant disease in either lung or liver (95.8%) compared with those affected in both lung and liver (57.1%, P=0.028). Further, prognostic markers were the response of metastases to preoperative chemotherapy (P=0.0138), high-risk histology (P=0.024), and local stage (P=0.026). Five-year overall survival was 82.1% and 5-year event-free survival was 67.9%. The overall follow-up time was 74.1 and 87.2 (2 to 151) months among survivors, and the treatment-related complication rate was 16.7%. In conclusion, in our series of stage 4 WT, prognosis was excellent if histology was favorable, metastatic disease was isolated to either lungs or liver, and if metastases responded to preoperative chemotherapy.