Oral mucositis in childhood cancer patients receiving high‐dose methotrexate: Prevalence, relationship with other toxicities and methotrexate elimination

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.