New risk classification is necessary in the treatment of Wilms tumor
The National Wilms Tumor Group (NWTS) presented the clinicopathological findings predicting relapse in children with stage III favorable-histology (FH) Wilms tumor (WT) treated in the NWTS-5 study. They reported that lymph node involvement and a microscopic residual tumor were highly predictive of the EFS and OS, and concluded that patients with different stage III criteria may receive different therapies. These data suggest that the current risk classification of WT is not satisfactory. Like other pediatric tumors, such as neuroblastoma and rhabdomyosarcoma, more systemic and detailed risk classification for WT should be established using various clinical and biological markers. In the previous therapeutic protocols for WT, no biological marker was used for risk classification. Therefore, it is important to identify effective biological markers related to the prognosis of WT. The presence of LOH at 1p and 16q was associated with a worse EFS and OS, and was used for risk classification to choose the treatment regimens used in the recent COG clinical trials. There are some candidate prognostic factors that can be used in the future risk classification of WT, such as the methylation status of RASSF1A. A worldwide cooperative study should be conducted in the future to confirm whether these factors are useful in the risk classification. The goal of treatment for WT is to identify approaches that provide excellent outcomes for children with low-risk tumors without the need for chemotherapy or XRT. Conversely, more aggressive therapy may be used for children with high-risk tumors in an effort to improve their survival. To meet these goals, a new effective risk classification for WT should be established via collaborative clinical trials.