Cost-effectiveness analysis supports genetic testing before patients with metastatic colorectal cancer are given irinotecan
Research Activities, May 2010, No. 357
Testing patients with metastatic colorectal cancer for a variant of a gene involved in metabolizing the drug irinotecan may reduce treatment costs and may slightly increase quality-adjusted life expectancy in patients who metabolize the drug more slowly than normal, when effectiveness is not diminished by dose reduction. Patients with two copies of the *28 variant of the uridine diphosphate glucuronosyltransferase 1A1 gene (UGT1A1*28) are slower in removing the active form of irinotecan from their bloodstream, resulting in an increased risk of severe loss of certain white blood cells (neutrophils). This loss, neutropenia, can lead to hospitalization or even death.
The researchers used findings from previous clinical studies and Medicare payment data to create a mathematical model to calculate cost effectiveness of reducing irinotecan dosage by 25 percent for the 11 percent of patients with metastatic colorectal cancer who have two copies of UGT1A1*28. The model indicated that making this change in treatment based on genetic testing would avoid an average of 84.5 cases of severe neutropenia (including 4.5 deaths) and save $2.7 million in treatment costs for every 10,000 patients tested.
Chemotherapy regimens including irinotecan are used on the approximately 30,000 patients annually diagnosed with metastatic colorectal cancer, as well as those with certain tumors of the upper digestive tract and the central nervous system. These other uses should be taken into account when determining the cost-effectiveness of the genotyping-dose reduction approach to "personalized" treatment, suggest the researchers. Their study was funded in part by the Agency for Healthcare Research and Quality (HS16075).
More details are in "Cost effectiveness of pharmacogenetic testing for uridine diphosphate glucuronosyltransferase 1A1 before irinotecan administration for metastatic colorectal cancer," by Heather Taffet Gold, Ph.D., Michael J. Hall, M.D., M.S., Victoria Blinder, M.D., and others in Cancer 115(19), pp. 3858-3867, 2009.