Cost-effectiveness of HER-2 testing strategies to select women with metastatic breast cancer (MBC) for treatment with trastuzumab

768 Background: In the pivotal trial of trastuzumab (Herceptin) (N=469), Herceptin in combination with chemotherapy improved survival when administered as first-line therapy to women with MBC who were HER-2+ by immunohistochemistry (IHC). In a retrospective analysis of data from this trial, the benefits of Herceptin were found to be greatest in patients who were HER-2+ by fluorescence in-situ hybridization (FISH). Despite higher costs, primary FISH testing to identify women who may benefit from Herceptin may be economically justified. Methods: A decision-analytic model was developed to evaluate the cost-effectiveness of five strategies for identifying women with HER-2+ MBC. These strategies used IHC only, IHC and FISH, or FISH only: (1) treat if IHC 2+ or 3+, (2) treat if IHC 3+; IHC then FISH, (3) FISH if IHC 2+, treat if IHC 3+ or FISH+, (4) FISH if IHC<3+, treat if IHC 3+ or FISH+; FISH alone (5) treat if FISH+. FISH+ patients were assumed to be HER-2+. Probabilities of progression, death, and cardiac ...