Researchers develop promising new breast cancer diagnostic marker

Indiana University School of Medicine researchers have developed a new breast cancer diagnostic marker that could enable physicians to more easily determine which patients have a less aggressive form of the disease that may not require chemotherapy treatment.

The marker has been licensed by Clarient Inc., a California-based cancer diagnostics company that plans to develop a commercial test based on the research by Harikrishna Nakshatri, B.V.Sc., Ph.D., Marian J. Morrison Professor of Breast Cancer Research, and Sunil Badve, M.D., associate professor of pathology and laboratory medicine.

In two studies involving nearly 675 patients, Nakshatri and Badve found that patients who tested positive for the presence of the biomarker - a protein called FOXA1 - were patients whose cancer is generally considered less aggressive.

About 70 percent of breast cancer patients have tumors that are "estrogen receptor positive," meaning that the hormone estrogen stimulates the tumors to grow. However, nearly two-thirds of the estrogen receptor positive patients have a subtype that is less aggressive and is associated with a better prognosis - most of whom also tested positive for the FOXA1 biomarker.

A commercial test based on the biomarker - for which IU and the IU School of Medicine researchers are seeking a patent - could be a significantly less expensive alternative to existing methods to test for breast cancer subtypes that require sophisticated genomic analyses.

"This is something that 80 percent of surgical pathology labs up and down the country could do," said Dr. Badve.

"Even in a developing country, a third-world country, these things can be easily done," said Dr. Nakshatri.

Those patients who test positive for the biomarker are more likely to respond to anti-estrogen hormone therapies, such as tamoxifen, the researchers said. For other patients the standard of care would be chemotherapy.

The IU researchers, working with scientists in North Carolina, Canada, Britain and Italy, tested the diagnostic capabilities of the FOX1A biomarker in two retrospective studies - meaning that tests were conducted on tissue samples from patients who had been treated for breast cancer. The first study, published in the Aug. 1, 2007, edition of Clinical Cancer Research, studied samples from 438 patients with a median of more than 15.4 years of followup.

A second study, of 245 cases with a median followup of more than 5 years, was published in the Nov. 15, 2007, edition of the Journal of Clinical Pathology. Data from a third study, with 4,000 cases, was recently completed in collaboration with researchers at the University of British Columbia and data from the research are being analyzed.

Financial support for the research was provided by the National Institutes of Health, including the National Cancer Institute, Sanofi-Aventis and Breakthrough Breast Cancer.