Physician compliance and relapse rates of acute lymphoblastic leukemia in children.

We studied the prescription patterns of maintenance therapy for children with acute lymphoblastic leukemia and their association with duration of complete remission. Both 6-mercaptopurine and methotrexate (MTX) were prescribed in doses significantly lower than those recommended (75 mg/m2 daily 6-mercaptopurine; 20 mg/m2 weekly MTX) during maintenance therapy. Of 212 evaluated patients, patients who had relapses (n = 101) received significantly less MTX compared with patients who did not have relapses (n = 111) during the first 2 years of maintenance therapy. In the group of standard-risk patients who received the same induction therapy (n = 92), 11 of 17 who received less than 50% of the recommended MTX dose (64%) and 28 of 75 who received greater than 50% of the dose (37%) had relapses (P less than 0.05). The two groups had comparable periods of interruption of MTX therapy. Further analysis revealed that the lower maintenance dose stemmed from a continuous low prescribed dose and not from more frequent interruption of therapy in relapse. Physicians' inability or failure to adhere to the recommended protocol was associated with a higher relapse rate of acute lymphoblastic leukemia. Improved physicians' compliance may improve the prognosis of the disease.