Imaging, Diagnosis, Prognosis Microarray-Based Determination of Estrogen Receptor, Progesterone Receptor, and HER2 Receptor Status in Breast Cancer

Purpose: The level of estrogen receptor (ER), progesterone receptor (PR), and HER2 aids in the determination of prognosis and treatment of breast cancer. Immunohistochemistry is currently the predominant method for assessment, but differences in methods and interpretation can substantially affect the accuracy, resulting in misclassification. Here, we investigated the association of microarray-based mRNA expression levels compared with immunohistochemistry. Experimental Design: Microarray mRNA quantification of ER, PR, and HER2 was done by the developed TargetPrint test and compared with immunohistochemical assessment for breast tumors from 636 patients. Immunohistochemistry was done in a central laboratory and in an independent reference laboratory according to American Society of Clinical Oncology/College of American Pathologists guidelines for 100 cases. For HER2 immunohistochemistry 2+ cases, additional chromogenic in situ hybridization (CISH) was used to determine the final status. Results: ER concordance between microarray and central immunohistochemistry was 93% [95% confidence interval (95% CI), 91-95%]. Only 4% of immunohistochemistrypositive samples were classified negative using microarray, whereas 18% of immunohistochemistry-negative samples showed a positive microarray ER status. Concordance for PR was 83% (95% CI, 80-86%) and 96% of all samples showed an identical classification of HER2 status by microarray and immunohistochemistry/CISH (95% CI, 94-98%). Nine percent of immunohistochemistry HER2-positive samples showed a negative microarray classification. Detailed review of 11 cases with discordant classifications by American Society of Clinical Oncology/College of American Pathologists and central immunohistochemistry indicated that microarray assessment was likely to add additional information in 5 cases. Conclusion:Microarray-based readout of ER, PR, andHER2 showsahigh concordancewith immunohistochemistry/CISH and provides an additional, objective, and quantitative assessment of tumor receptor status in breast cancer. (Clin Cancer Res 2009;15(22):7003–11) Breast cancer is the most common malignancy in women. The level of estrogen receptor (ER) and progesterone receptor (PR) is prognostic in early-stage breast cancer patients and predictive for response to tamoxifen and other hormonal therapies (1–4). HER2 overexpression and/or amplification is an additional prognostic molecular marker (5) indicated for selection of patients for trastuzumab or other HER2-targeted therapies (6, 7). Accordingly, primary breast carcinomas should be tested for these three molecular markers for optimal diagnosis and treatment selection for the patient. Immunohistochemistry is currently the predominant method for determination of ER, PR, and HER2 status (8), often with additional in situ hybridization assays to clarify HER2 immunohistochemical results (9). Despite its long-term use, immunohistochemical assays have not been standardized Authors' Affiliations: Agendia BV; Divisions of Experimental Therapy and Medical Oncology and Department of Pathology, Netherlands Cancer Institute; Department of Pathology, Academic Medical Centre, Amsterdam, The Netherlands and Agendia, Inc., Huntington Beach, California Received 2/24/09; revised 8/19/09; accepted 8/19/09; published OnlineFirst 11/3/09. Grant support: Top Institute Pharma project T3-108. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. Requests for reprints: Marc J. van de Vijver, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Phone: 31-20-5664100; Fax: 31-20-566-9523; E-mail: [email protected] and Annuska M. Glas, Agendia BV, Science Park 406, 1098 XH Amsterdam, The Netherlands. Phone: 31-20-462-1500; Fax: 31-20-462-1505; E-mail: [email protected]. F 2009 American Association for Cancer Research. doi:10.1158/1078-0432.CCR-09-0449 7003 Clin Cancer Res 2009;15(22) November 15, 2009 www.aacrjournals.org Research. on June 1, 2017. © 2009 American Association for Cancer clincancerres.aacrjournals.org Downloaded from Published OnlineFirst November 3, 2009; DOI: 10.1158/1078-0432.CCR-09-0449