Prognosis of women with metastatic breast cancer by HER2 status and trastuzumab treatment: an institutional-based review

Abstract

PURPOSE The purpose of this study was to determine whether trastuzumab improves prognosis of women with metastatic human epidermal growth factor receptor 2 (HER2)/neu -positive breast cancer beyond that of women with HER2/neu-negative disease. PATIENTS AND METHODS Two thousand ninety-one women with metastatic breast cancer diagnosed from 1991 to 2007, with known HER2/neu status and who had not received trastuzumab in the adjuvant setting, were identified. Disease was classified into the following three groups: HER2/neu negative, HER2/neu positive without first-line trastuzumab treatment, and HER2/neu positive with first-line trastuzumab treatment. Overall survival (OS) was estimated using the Kaplan-Meier product-limit method and compared between groups with the log-rank test. Cox proportional hazards models were used to determine associations between OS and HER2/neu status after controlling for patient characteristics. Results One hundred eighteen patients (5.6%) had HER2/neu-positive disease without trastuzumab treatment, 191 (9.1%) had HER2/neu-positive disease and received trastuzumab treatment, and 1,782 (85.3%) had HER2/neu-negative disease. Median-follow-up was 16.9 months. One-year survival rates among patients with HER2/neu-negative disease, HER2/neu-positive disease and trastuzumab treatment, and HER2/neu-positive disease and no trastuzumab treatment were 75.1% (95% CI, 72.9% to 77.2%), 86.6% (95% CI, 80.8% to 90.8%), and 70.2% (95% CI, 60.3% to 78.1%), respectively. In a multivariable model, women with HER2/neu-positive disease who received trastuzumab had a 44% reduction in the risk of death compared with women with HER2/neu-negative disease (hazard ratio [HR] = 0.56; 95% CI, 0.45 to 0.69; P < .0001). This HR varied with time and was significant for the first 24 months and not significant after 24 months. CONCLUSION Our results show that women with HER2/neu-positive disease who received trastuzumab had improved prognosis compared with women with HER2/neu-negative disease.

Conflict of interest statement

Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.

Figures

Fig 1.

Overall survival by trastuzumab treatment group.

Fig 2.

Overall survival stratified by trastuzumab treatment group and according to hormone receptor (HR) status: (A) HR-negative disease and (B) HR-positive disease.