Compliance with a protocol for acute lymphoblastic leukemia in childhood

BACKGROUND: Remission rates achieved after the initial treatment of acute lymphoblastic leukemia may be similar in both developed and developing countries, but relapse rates are much higher in the latter. Thus, other reasons are needed, in addition to biological characteristics of the leukemic cells themselves, to explain the unfavorable evolution of patients living in unfavorable socioeconomic and cultural conditions. OBJECTIVE: The aim of this study was to retrospectively evaluate compliance to an acute lymphoblastic leukemia treatment protocol. METHODS: Main abstracted data were: total duration and reasons for interruption of chemotherapy, prescribed doses of 6-mercaptopurine, and median white blood cell and neutrophil counts during the maintenance phase. Interruptions of chemotherapy were considered inappropriate if they did not follow predetermined criteria established in the protocol. RESULTS: Fourteen of 73 patients (19.2%) unduly interrupted chemotherapy by determination of their physicians. The median white blood cell count was higher when compared with the protocol recommendations; the median 6-MP dose was lower than the standard recommended dose. The estimated probability of event-free survival was higher for patients with lower median leukocyte counts and close to those predetermined by the protocol. Event-free survival was also higher for children with a higher percentage of days without chemotherapy due to bone marrow or liver toxicity excluding undue interruptions. In multivariate analysis, both factors remained statistically significant. These results suggest that the intensity of maintenance chemotherapy may not have been enough in some children, to achieve adequate myelosuppression, hence the observation of higher leukocyte counts and none or rare episodes of therapy interruption. CONCLUSIONS: Compliance to the therapeutic protocol by both doctors and patients should always be considered in the evaluation of therapeutic failure in acute lymphoblastic leukemia; strict adherence to treatment protocols contributes to better treatment results in acute lymphoblastic leukemia children.