Barriers to the enrollment of children in the Children's Oncology Group study of very low risk Wilms tumor: a report from the Children's Oncology Group.

Very low risk Wilms tumor is defined by favorable histology, age below 2 years, tumor weight less than 550 g, and stage I. The Children's Oncology Group is currently studying a nephrectomy-only strategy for these patients but the accrual rate is slightly below expected. Twenty-five of 31 institutions responded with reasons by physicians and/or parents for electing not to participate. Parents were primarily concerned with the experimental nature of the study, whereas physicians were concerned about accurate staging, with some overlap. We point out the necessity of assessing these concerns in predicting feasibility of and accrual to a therapy reduction study.