Background: The authors estimated survival among patients with chronic myeloid leukemia for a cost-effectiveness analysis of imatinib versus interferon-alpha plus low-dose cytarabine (IFN+LDAC).
Methods: Two-year survival and cytogenetic response were determined using data from 553 patients who received first-line imatinib in the International Randomized Interferon versus ST571 Study (IRIS). Long-term survival was modeled on complete cytogenetic response (CCyR) after 2 years. Long-term survival for patients with a CCyR was modeled using data from a cohort study of 317 patients with CCyRs. Long-term survival for patients without a CCyR was modeled using data from a trial of 275 patients who were treated with IFN+LDAC. Computation of lifetime survival estimates for imatinib assumed a proportional hazards relation between survival for an age-matched and gender-matched cohort and survival for patients with and without a CCyR.
Results: For IRIS patients receiving imatinib, the estimated survival was 95.8% and the CCyR rate was 73.8%. The average residual life expectancy was estimated to be 16.71 years for CCyR patients and 5.78 years for non-CCyR patients. The estimated life expectancy after treatment with imatinib was 15.30 years, compared with 9.07 years for patients who were treated with IFN+LDAC in previous studies.
Conclusions: Assuming the relation between CCyR and survival with interferon-alpha holds for imatinib, higher CCyR rates with imatinib therapy will result in an estimated 6.23 life-years gained compared with treatment with IFN+LDAC.
(c) 2004 American Cancer Society