Regarding direct comparisons of IHC to FISH from a clinical perspective, particularly for patients with IHC 0 or 1+ results and HER2 amplification using FISH, evidence points to these IHC false-negative cases responding to HER2-targeted therapy with hazard ratios similar to those patients with HER2 amplification and IHC 3+ immunostaining. The converse is not true for patients with IHC 3+ immunostaining when whose tumors are not HER2-amplified by FISH. Thus, from a clinical and economic perspective, the case for primary, gene-based testing is compelling.
While more current data may reflect higher rates of using gene-based tests, one recent study of a Medicare population demonstrated that 93% of patients were tested using IHC, and another across multiple payers showed that the primary test was IHC in 68% of patients whose HER2 status was evaluated.[38,39] A shift to primary testing using gene-based methods will improve the overall response to therapy, while providing a cost-effective return on investment. Furthermore, enhanced diagnostics will improve ongoing and future clinical trials regarding anti-HER2 therapy by providing more accurate estimates of expected therapy response. With the enhanced convenience of gene-based tests and increased clinical benefits and cost of new anti-HER2 therapies, HER2 testing guidelines warrant review and revision.
Expert Rev Pharmacoeconomics Outcomes Res. 2011;11(3):325-341. © 2011 Expert Reviews Ltd.
Cite this: Clinical and Health Economic Outcomes of Alternative HER2 Test Strategies for Guiding Adjuvant Trastuzumab Therapy - Medscape - Jun 01, 2011.