[Evaluation of severe side effects of high-dose methotrexate in osteosarcoma]

Severe toxicity associated with high-dose methotrexate (HD-MTX) combined with citrovorum factor rescue (CR-Rescue) was evaluated in the 365 courses in 54 patients with osteosarcoma. Anaphylactoid reaction developed in 8 patients (14.8%), 8 courses (2.2%). The mean age was 14 years old. The total dose given was 85770mg in mean and 1840 mg per body weight (kg). The occurrence was proportional to the dose and the number of the course. Plasma MTX concentration remained under 10(-7) mol/l during the episode. Delayed clearance of MTX from plasma was treated with massive CF-Rescue in 10 patients (19%) (the mean age of 13.6), in 12 courses (3.3%), which was observed on an average at the 7th course when the total dose reached to 59530 mg, or 1390 mg per body weight (kg). Neurotoxicity was observed in only one patient (1.9%), one course (0.3%). Severe toxicity associated with HD-MTX therapy tended to occur according to dose escalation and the number of administration. To overcome severe toxicity careful observation of clinical symptoms and signs as well as adequate treatment of side effects without delay are of importance.