Background: Amplification and/or overexpression of the HER2/neu gene is associated with a poor prognosis in breast cancer. Many studies have suggested that this gene may be associated with the relative efficacy of chemotherapy and endocrine therapy options.
Methods: A systematic review of the evidence was conducted. MEDLINE, EMBASE, the Cochrane Library, the American Society of Clinical Oncology annual meeting proceedings, and the San Antonio Breast Cancer Symposia proceedings were all searched to November 2006 for reports of analysis by HER2/neu status of the relative efficacy of the treatment arms in randomized controlled trials.
Results: Thirty-five trials were identified. A meta-analysis of trials of tamoxifen versus observation found no significant interaction between treatment and HER2/neu status, although one trial not included in the meta-analysis did find interaction. A meta-analysis of adjuvant anthracycline-based chemotherapy trials found a significant interaction (difference in disease-free survival log-hazard ratios -0.31, 95% confidence interval -0.50 to -0.13; difference in overall survival log-hazard ratios -0.34, 95% confidence interval -0.53 to -0.14). Significant interaction was also found in a meta-analysis of disease-free survival in trials of adjuvant taxane therapy versus non-taxane therapy (difference in disease-free survival log-hazard ratios -0.36, 95% confidence interval -0.68 to -0.04). HER2/neu overexpression and/or amplification was associated with greater efficacy of the anthracycline or taxane regimen.
Conclusions: Current evidence supports the conclusion that the benefit of both anthracycline-based and taxane-based adjuvant chemotherapy is associated on HER2/neu status, with patients with HER2/neu-positive cancers benefiting more from these therapies than those with HER2/neu-negative cancers.