DISEASE CHARACTERISTICS: Case or control patient clinically eligible for a Pediatric Oncology Group (POG) frontline therapeutic protocol, whether or not the protocol was submitted to or approved by the physician's Institutional Review Board Case patients must not have enrolled on the POG frontline protocol due to decision by the physician or patient/parent Control patients must have been enrolled on the POG frontline protocol Ineligible if offered treatment on an in-house therapeutic protocol (institutional review board-approved) rather than the POG protocol