Cost-effectiveness for extended RAS/RAF testing in metastatic colorectal cancer.

3572 Background: Epithelial growth factor receptors (EGFR) inhibitors (Cetuximab and panitumumab) are monoclonal antibodies directed against EGFR and promote apoptosis. Douillard et al demonstrated the benefit of using EGFR inhibitors agents in wild type (WT) KRAS metastatic colorectal cancer (mCRC) and lack of benefit in mutated KRAS mCRC patients. Only WT KRAS mCRC are candidate for EGFR inhibitors, they constitute 57.6% of all mCRC patients, 27.3% of them carry other RAS/RAF mutations that preclude them from EGFR inhibitors benefits. Insurance companies are willing to pay the cost of KRAS testing and EGFR inhibitors treatment for all WT KRAS mCRC. We conducted this analysis to assess the cost-effectiveness of the extended testing for other RAS/RAF mutations for WT KRAS mCRC patients. Methods: A decision analysis model using (Treeage pro Software, Williamstown, MA) was developed to assess and compare treatment costs and disease outcomes associated with presence or absence of additional mutations (RAS/RAF) in a WT KRAS mCRC. . For utility estimate, Quality of life (QoL) assessment based on Skindex-16 for EGFR inhibitors side effects. The difference in median survival time was used to calculate incremental effectiveness of using EGFR inhibitors based on the extended testing or not. Costs were determined through Medicare records and direct hospital charges for extended testing, and treatment with EGFR inhibitors. For sensitivity analysis, we modify mutations probability and the extended testing cost, in both 1-way and combined 2-way sensitivity analyses. Results: The total expected cost was $56,306.06 vs. $42,683.75 favoring additional testing. The median overall survival was 15.8 vs.14.5 months favoring additional testing. In order to conclude extended testing is not worth it, mutation probability has to be less than 1.8%, or extended testing cost of more than 14000 $ in one way sensitivity testing. However, for two-way analysis, the mutation probability needs to be less than 17% and test cost needs to be more than $8,200. Conclusions: Our analysis shows that extended testing for other RAS/RAF mutations is cost-effective in WT KRAS mCRC patients before treating with EGFR inhibitors.