Abstract A30: Cost-effectiveness analysis of HER2 testing methods in adjuvant treatment of HER2 breast cancer

Abstract

Abstract Background: Trastuzumab is a targeted therapy indicated for the treatment of HER2-postive breast cancers, an aggressive form of this disease. HER2 status can be assessed using two tests: florescence in situ hybridization (FISH), which tests for HER2 gene amplification; or immunohistochemistry (IHC), which tests for HER2 protein overexpression. There is considerable debate regarding which of these tests should be used for HER2 detection due to differences in cost, accuracy, and health outcomes. Objective: To compare the outcomes and cost effectiveness of FISH and IHC for HER2 testing in breast cancer. Design: Based on data from outpatient electronic medical records, decision models were designed for FISH, IHC and No Test scenarios (in which all patients received trastuzumab without being tested). Each model considered costs and health outcomes. Treatment possibilities included chemotherapy (with or without trastuzumab), radiation therapy, and surgery. Cost for trastuzumab adverse events were also included. Point estimate analysis and Monte Carlo simulations (varying false positive rates of tests) were used to determine results. Data: A hypothetical cohort of 100,000 female breast cancer patients. Interventions: Testing with FISH or IHC followed by subsequent trastuzumab treatment when indicated (i.e., when the test result is positive for HER2), which included false positive and false negative results. Outcome Measures: Medical costs, Quality Adjusted Life Years (QALYs) and percentage of patients correctly tested (true positives who test as positive and true negatives who test as negative). Results: The expected per-patient costs of the No-test model, IHC model and FISH model were $166,360, $72,405, and $64,626 respectively. The expected values of total QALYs experienced by IHC and FISH groups were essentially identical. Using Monte Carlo analysis to vary test accuracy rates also indicated decreased costs and improved outcomes for FISH. In addition, FISH had increased levels of correct HER2 status detection when compared with IHC: if tested with FISH rather than IHC, there was a 3.58% increase in probability that a patient who is HER2 positive will be diagnosed as positive and a 15.66% increase in probability that a patient who is HER2 negative will be diagnosed as negative. Conclusions: FISH should replace IHC as the preferred method of choice for HER2 testing. This would result in increased cost-effectiveness of testing and treatment for HER2 breast cancer. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A30.