HOUSTON - Two critical characteristics of breast cancer that are important to treatment can be identified by measuring gene expression in the tumor, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reports in Lancet Oncology online.
Researchers developed and validated a new genomic microarray test that identifies whether a tumor's growth is fueled by the female hormone estrogen and the role of a growth factor receptor known as HER-2 that makes a tumor vulnerable to a specific drug. The status of these factors is now determined by pathology tests.
"This is one important step towards personalized diagnosis and treatment planning based on an integrated genomic test of an individual tumor," said senior author W. Fraser Symmans, M.D., associate professor in the M. D. Anderson Department of Pathology. The Lancet Oncology paper results are the latest in an effort by the research team to develop a single test to quickly and efficiently determine the characteristics and vulnerabilities of a patient's breast cancer and ultimately to guide treatment.
About 70 percent of breast cancers are estrogen-receptor positive and another 15 to 25 percent are human epidermal growth factor receptor-2 (HER-2) positive. Each receptor status requires different types of treatment.
The gene expression tests were 90 percent accurate for both receptors, which makes them comparable to, if not better than, existing pathology tests.
"This moves us closer to developing an integrated single genomic test that could estimate the risk of cancer relapse after surgery, determine the ER and HER2 receptor status, and also gauge the sensitivity of the tumor to hormone therapy and chemotherapy," says Lajos Pusztai, M.D., Ph.D., associate professor in the M. D. Anderson Department of Breast Medical Oncology, and team leader with Symmans.