[Toxicity of high dose methotrexate repeated infusions in children treated for acute lymphoblastic leukemia and osteosarcoma].

We evaluated and compared hematologic, hepatic and renal cumulative toxicity of high dose methotrexate (HDMTX) repeated courses in two groups of pediatric patients: 22 patients affected by "non B" acute lymphoblastic leukemia (ALL) treated, in consolidation phase, with four courses of HDMTX 5 g/mq given intravenously over 24 hours infusion (for a total of 88 courses) according to the Italian Cooperative Protocols AIEOP LLA-88; 18 patients affected by non metastatic osteosarcoma of extremities (OST) treated, in preoperative and postoperative phases, with five courses of HDMTX 8 g/mq given intravenously over 6 hours infusion (for a total of 90 courses) according to CNR-NEO 2 protocol. Severe myelosuppression (neutropenia < 500/microliters and/or thrombocytopenia < 25000/microliters) was more frequently observed in ALL (7% of infusions) than in OST (3%). Hepatotoxicity (serum transaminase elevation > 350 IU/l) was significantly more frequent (p < 0.001) in OST (32% of courses) than ALL (6%). Nephrotoxicity was assimilable in the two groups and the elevation of serum creatinine was never higher than 1.9 mg/dl. We did not observe any increase of hematologic, hepatic and renal toxicity following the HDMTX courses repetition.