Breast cancer is apparently the second major cause of cancer-related death among women. The U.S. Food and Drug Administration has announced the approval of a new genetic trial that may give doctors a clue whether women with breast cancer also suffer from a condition known as HER2. Subsequently, if tested positive they become eligible for Herceptin, which is a commonly used breast cancer treatment.
The test involves the examination of tumor tissue to check the number of copies of HER2 gene present. The gene is known to be present on chromosome 17 in human cells. A certain protein produced by this gene is apparently present in specific cancer cells that are inclusive of breast cancer cells. The test is known as the Inform Dual ISH test.
As a part of the analysis, lab attendants will examine a small area of the breast tumor to keep a tab on how many copies of HER2 genes are present on chromosome 17. The area of inspection is painted with chemicals that cause the gene and chromosome to react with changes in color. The HER2 genes appear black whereas copies of chromosome 17 seem to be red in color as observed in a standard microscope.
The test allows lab attendants to gauge HER2 and chromosome signals for longer periods. They can test both the specimens on the same slide which is similar to the HER2 amplification measurements that were formerly used only with fluorescence microscopes.
“When used with other clinical information and laboratory tests, this test can provide health care professionals with additional insight on treatment decisions for patients with breast cancer,” specified Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostic Device Evaluation and Safety in the FDA’s Center for Devices and Radiological Health.
The FDA approval came only after a U.S study involving tumor samples from 510 patients with breast cancer was conducted. It came to light that the test seemingly helped in validating if a patient’s tumor sample contained abnormal and high number of copies of the gene, for 96 percent of HER2 positive tumor samples. Patients, who possessed more than the normal number of copies of the gene, are regarded as candidates for Herceptin therapy.
On the same lines, the test ruled out the situation that more than normal number of HER2 copies may be found in 92.3 percent of HER2 negative tumor samples. Thus patients who have normal number of the gene’s copies are not eligible for Herceptin therapy. The study essentially involves identifying patients who are HER2 positive which may be a useful tool for considering the Herceptin treatment for breast cancer patients.
Tuscon, Ariz.-based Ventana Medical Systems manufactures the Inform Dual ISH test for examination of the tumor.