RESUMEN
BACKGROUND: Oral mucositis (OM) is one of the main adverse effects of the chemotherapeutic agent methotrexate (MTX). AIM: To evaluate the relationship of OM with MTX metabolism time and other toxicities in childhood, cancer patients receiving high-dose of methotrexate (HD-MTX). DESIGN: Seventy-seven childhood patients receiving HD-MTX for treatment of leukaemia, osteosarcoma or lymphoma were evaluated. MTX serum level, hepatic and renal function parameters, and presence and intensity of OM were analysed. RESULTS: The patients were submitted to 255 cycles of chemotherapy. OM was diagnosed in 191 (74.9%) cycles. Of these, 119 (46.6%) presented ulcerative lesions. Lymphoma was associated with severe OM (P = .01). OM was associated with higher serum levels of aspartate aminotransferase (P = .006), alanine aminotransferase (P = .04) and creatinine (P = .008). Increase of one unit of total bilirubin and indirect bilirubin associated, respectively, with 11% and 39% higher prevalence of OM. For each increase of one unit of creatinine serum level, it was observed a 37% higher prevalence of OM in patients with lymphoma. No association was found between delayed excretion of MTX and OM development. CONCLUSIONS: OM is a prevalent complication of childhood cancer patients receiving HD-MTX. Renal and hepatic toxicity could be considered risk factors for OM, especially in patients with lymphoma.