Survival of Patients with Chronic Myelocytic Leukemia: Comparisons of Estimates from Clinical Trial Settings and Population-Based Cancer Registries

Introduction. The survival of patients with chronic myelocytic leukemia (CML) has improved during the past decades. However, there have been discrepancies between results reported from clinical trials and population-based studies. We aimed to elucidate the extent of these discrepancies. Methods. We examined the 5-year survival rate of patients in clinical trials of CML treatment and compared these results with the survival of patients in the general population using the Surveillance, Epidemiology, and End Results (SEER) database, correcting for differences in the age structure of the patient populations. Results. Twenty-nine trials were identified for data extraction. The survival rate calculated from SEER data was lower than the survival rate in clinical trials in the corresponding period, with differences of 2.1%-50.7%. Age-adapted survival was similar for four trials, but differences up to 35.8% were seen in most. Limitations of the study include the lack of information on chemotherapy in the SEER database and possible heterogeneity of cases. Discussion. The survival rate in clinical trials of CML treatment is higher than the survival rate of all patients with CML. We speculate that the difference may be a result of access to better medications, selection of healthier patients for trials, and the time necessary for adoption of new treatments. This finding underscores the need for population-based studies to give a more realistic idea of survival for patients with a given malignancy in the general population. The Oncologist 2011;16:663-671