Age disparity in the dissemination of imatinib for treating chronic myeloid leukemia

Abstract

Background: Imatinib is a highly effective treatment for chronic myeloid leukemia. It was approved by the Food and Drug Administration in 2001 and thereafter rapidly became front-line therapy. This study characterized the prevailing chronic myeloid leukemia therapies in the United States and assessed the impact of imatinib on chronic myeloid leukemia survival and mortality rates in the general population.

Methods: Investigators with the National Cancer Institute's Patterns of Care study reviewed medical records and queried physicians regarding therapy for 423 patients with chronic myeloid leukemia diagnosed in 2003 who were randomly selected from cancer registries in the Surveillance, Epidemiology, and End Results Program. Characteristics associated with the receipt of imatinib were documented, as were survival differences between those who received imatinib and those who did not. Population-based data were used to assess chronic myeloid leukemia survival and mortality rates in time periods before and after the introduction of imatinib.

Results: Imatinib was administered to 76% of patients in the Patterns of Care study. Imatinib use was inversely associated with age: 90%, 75%, and 46% for patients ages 20 to 59 years, 60 to 79 years, and 80 or more years, respectively. Elderly patients who received imatinib survived significantly longer than those who did not. After adjusting for age, imatinib use did not vary significantly by race/ethnicity, socioeconomic status, urban/rural residence, presence of comorbid conditions, or insurance status. Overall, chronic myeloid leukemia survival in the Surveillance, Epidemiology, and End Results population improved, and mortality in the United States declined dramatically during the period when imatinib became widely available; these improvements diminished with increasing age.

Conclusion: Age disparities in treatment with imatinib likely contributed to worse survival for many elderly patients with chronic myeloid leukemia.

Figure 1

Survival (months) among Patterns of Care Study subjects by age at diagnosis and imatinib utilization status. A- 20–59 years of age. B- 60–79 years of age. C- 80 and over years of age. These data indicate that elderly patients that did not receive imatinib fared more poorly compared to those that did. There was no significant difference in socioeconomic status or co-morbidities between those that received imatinib and those that did not.

Figure 2

Survival (months) for chronic myeloid leukemia cases in nine core Surveillance, Epidemiology, and End Results (SEER) Program participants by age at diagnosis and time period of diagnosis. A- 20–59 years of age. B- 60–79 years of age. C- 80 and over years of age. These data indicate that elderly patients with CML had a worse survival on a population basis.

Figure 3

Joinpoint analysis of chronic myeloid leukemia (CML) patients by age at year of death. These data show that there has been an overall improvement in survival of chronic myeloid leukemia patients in the imatinib era, but that this improvement extends less well to elderly patients.