Background: Testing technologies are increasingly used to target cancer therapies. Human epidermal growth factor receptor 2 (HER2) testing to target trastuzumab for patients with breast cancer provides insights into the evidence needed for emerging testing technologies.
Methods: The authors reviewed literature on HER2 test utilization and cost effectiveness of HER2 testing for patients with breast cancer. They examined available evidence on: percentage of eligible patients tested for HER2; test methods used; concordance of test results between community and central/reference laboratories; use of trastuzumab by HER2 test result; and cost effectiveness of testing strategies.
Results: Little evidence was available to determine whether all eligible patients are tested, how many are retested to confirm results, and how many with negative HER2 test results still receive trastuzumab. Studies suggested that up to 66% of eligible patients had no documentation of testing in claims records, up to 20% of patients receiving trastuzumab were not tested or had no documentation of a positive test, and 20% of HER2 results may be incorrect. Few cost-effectiveness analyses of trastuzumab explicitly considered the economic implications of various testing strategies.
Conclusions: There was little information about the actual use of HER2 testing in clinical practice, but evidence suggested important variations in testing practices and key gaps in knowledge exist. Given the increasing use of targeted therapies, it is critical to build an evidence base that supports informed decision making on emerging testing technologies in cancer care.