This presentation is part of: Poster Session - CEA: Methods and Applications; Health Services Research
THE COST-EFFECTIVENESS OF TARGETED THERAPY FOR ADVANCED COLORECTAL CANCER
Elena B. Elkin, PhD and Deborah Schrag, MD, MPH. Memorial Sloan-Kettering Cancer Center, Department of Epidemiology and Biostatistics, New York, NY
PURPOSE: Targeted cancer therapies may improve clinical outcomes for the patients most likely to benefit, while sparing those unlikely to benefit the costs and possible harms of ineffective treatment. Among advanced colorectal cancer patients whose tumors express the epidermal growth factor receptor (EGFR), cetuximab in combination with chemotherapy has been shown to extend time-to-progression and survival. Despite the availability of an immunohistochemical assay (IHC) to identify the approximately 75% of patients whose tumors express EGFR, reports suggest that the test is not widely used. The purpose of this analysis was to assess the impact of EGFR testing on the cost-effectiveness of cetuximab therapy. METHODS: We constructed a Markov state-transition model to simulate clinical outcomes in a cohort of 65-year-old patients with metastatic colorectal cancer. We estimated the average costs and life-years saved (LYs) of three strategies: 1) no test, chemotherapy alone for all patients; 2) test with IHC, cetuximab plus chemotherapy for EGFR-expressers; 3) no test, cetuximab plus chemotherapy for all patients. Transition probabilities related to cancer progression and treatment efficacy were obtained from clinical trials. We assumed that cetuximab had no benefit in patients whose tumors did not express EGFR. Since the test characteristics of IHC for EGFR have not been well-described in colorectal cancer, we used two-way sensitivity analysis to examine the role of test sensitivity and specificity on the cost-effectiveness of alternative clinical strategies. RESULTS: In the absence of testing, the addition of cetuximab to standard chemotherapy for all patients increased treatment costs by approximately $66,000, and extended average survival by about 1.2 months, yielding an incremental cost-effectiveness ratio (ICER) of more than $680,000 per LYs. Use of a perfect test achieved the same survival benefit, but at a lower cost, with an ICER of $575,000. Assuming the test had 90% sensitivity and specificity, the ICER of targeted cetuximab therapy was less than $600,000 per LYs, and the ICER of universal cetuximab therapy was more than $1.5 million per LYs. CONCLUSIONS: Using IHC to identify cetuximab candidates can substantially improve the cost-effectiveness of this therapy for patients with advanced colorectal cancer. Even though the prevalence of tumor EGFR expression is relatively high in these patients, it is more cost-effective to use an imperfect test for targeting treatment, rather than prescribe cetuximab universally.
