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Breast Cancer

HER2 Testing and Subsequent Trastuzumab Treatment for Breast Cancer in a Managed Care Environment

^aHealthCore, Inc., Wilmington, Delaware, USA; ^bAmerican Imaging Management, Chicago, Illinois, USA; ^cUniversity of Rochester Medical Center, Rochester, New York, USA

Key Words. Breast cancer • Human epidermal growth factor receptor 2 • Trastuzumab • Guideline adherence • Managed care

Correspondence: John J. Barron, PharmD, Director, Research Operations, HealthCore, Inc., 800 Delaware Avenue, Fifth Floor, Wilmington, DE 19801, USA. Telephone: 302-230-2113; Fax: 302-230-2020; e-mail: jbarron{at}healthcore.com

Received December 23, 2008; accepted for publication July 13, 2009; first published online in THE ONCOLOGIST Express on August 14, 2009.

Disclosures: John J. Barron: Research funding/contracted research: Genentech; Mark J. Cziraky: Research funding/contracted research: Genentech; Thomas Weisman: None; David G. Hicks: Honoraria: Genentech BioOncology.

The content of this article has been reviewed by independent peer reviewers to ensure that it is balanced, objective, and free from commercial bias. No financial relationships relevant to the content of this article have been disclosed by the independent peer reviewers.

Background. Degree of physician adherence to 2001 guidelines recommending routine testing of human epidermal growth factor receptor 2 (HER2) status among newly diagnosed, recurrent, and metastatic breast cancer (BC) cases, and frequency of trastuzumab use in HER2-positive patients are not well documented.

Methods. Patients newly diagnosed with BC managed by an identifiable hematologist/oncologist between June 1, 2005 and June 30, 2006 were identified from an administrative claims database of three health plans (n = 3,521). From these, a subset of 380 patients was identified for medical chart review. HER2 testing (occurrence, type of test used), HER2 status (positive, negative, unknown), and trastuzumab usage were evaluated.

Results. HER2 testing occurred in 88% of all newly diagnosed patients with BC and in 98.1% of those with stage 1 or higher breast cancer (n = 322), for whom testing is recommended. Among those with HER2 testing performed (n = 335), 21.5% were positive (HER2⁺), 77.3% were negative (HER2^–), and 1.2% were unknown. Of the 52 patients who used trastuzumab, only one patient did not have documented HER2 overexpression. Of the 45 HER2⁺ women who had stage 2 or higher BC, 13% did not receive trastuzumab.

Conclusions. HER2 testing status was extremely high among newly diagnosed BC patients treated by hematologists/oncologists in a managed care environment. There was almost no evidence of inappropriate prescribing of trastuzumab, but 1 of every 7.5 patients with HER2-overexpressing stage 2 or higher breast cancer did not receive the agent.