We performed a randomized , placebo-controlled , double-blind trial of oral glutamic acid as a preventive agent in pediatric patients with cancer who would be receiving vincristine therapy for at least 9 consecutive weeks ( Stratum 1 = Wilms tumor and rhabdomyosarcoma ) or 4 consecutive weeks in conjunction with steroids ( Stratum 2 = Acute lymphoblastic leukemia and non-Hodgkin lymphoma ) .