College of American Pathologists
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Serum HER2 testing

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February 2002
William Check, PhD

In addition to screening breast tumors for HER2 with IHC and FISH, Specialty Laboratories of Santa Monica, Calif., also offers a serum test for HER2. Says Meeta Patnaik, MD, director of research: “Measuring HER2 concentration in the serum of patients with metastatic breast cancer is indicated for followup and monitoring these patients, whose initial serum HER2/neu is greater than 15ng/mL. We see it as more of a prognostic indicator, and additional studies are under way.”

Approved in December 2000, the serum assay (HER2/neu microtiter ELISA, Bayer Diagnostics) was recently assigned a CPT code, 83950.

Several large studies have shown that HER2 serum concentration is related to severity of disease, with 40 percent of stage IV breast cancers having a HER2 value >15 µg/L. Longitudinally, serum HER2 level parallels the course of disease; in patients who respond to therapy, HER2 concentration decreases, irrespective of type of therapy.

Specialty started offering serum HER2 testing in March 2001. “At first there wasn’t rapid pickup,” Dr. Patnaik says, “but the numbers have increased significantly over the last two to three months.”

Specialty Laboratories has a strategic alliance with Bayer’s Oncogene Sciences Group, providing it with early access to new product lines.