More than 207,000 American women will learn this year that they have breast cancer. The lucky ones will find out early, when breast cancer is the most treatable. If you are one of these women, tests will likely determine the treatment that is best for your type of cancer.
One of these tests determines if a woman has HER2-positive breast cancer. HER2 stands for Human Epidermal growth factor Receptor 2. Studies show that roughly one-quarter of all breast cancer patients are HER2-positive.
It is critical for your oncologist to determine if your cancer is HER2-positive because these tumors tend to grow and spread more aggressively therefore, require different therapy. Most often the drug Herceptin is used in additional to other breast cancer treatments.
Currently, many physicians use as many as three different tests to determine HER2 status. This practice is unnecessary for most breast cancer patients and adds considerable expense to treatment, says a recent research article published in the Journal of Clinical Oncology.
Mayo Clinic researchers believe a single, low cost molecular test known as ImmunoHistoChemistry (IHC), is enough for most patients to determine HER2 status. If the test is positive, Herception should be used. However, if the test is negative, a second test to check for HER2 genes should be ordered, the study says.
“It makes economic sense for oncologists to use the IHC test first,” says the study’s lead investigator, Edith Perez, M.D., a breast cancer researcher at the Mayo Clinic’s Florida campus. “Our data are very important for clinical practice and will likely change how these tests are ordered, resulting in savings for individual patients as well as for the nation.”
Researchers found that IHC and another more expensive test, a Fluorescence In Situ Hybirdization (FISH) analysis, equally predicted if a patient would benefit from Herceptin. A third test to measure chromosome 17 copy number was not found to be helpful at all. Some clinicians are using all three tests to determine HER2 status.
The researchers said there has been longstanding confusion over HER2 testing. IHC measures how much HER2 protein there is on the surface of cancer cells, and FISH checks to see if cancer cells have extra copes of the HER2 gene. The chromosome 17 analyses also looks for extra copies of that chromosome because it contains the HER2 gene.
Perez says if the IHC test scores 3 there is no reason to offer the much more expensive FISH test.
“Now, typically, many physicians want to “verify” positive IHC findings with FISH, or use FISH first, which some inaccurately regard as a more accurate test, and this study shows it is unnecessary and costly,” Perez said.
Prior to this study, it was a common perception if a patient had multiple copies of the HER2 gene it would predict a better outcome of adjuvant Herceptin, Perez said. “We proved that idea to be wrong. Patients with low levels of HER2 gene copies were just as likely to be free of disease relapse after receiving Herceptin added to chemotherapy as were patients with high levels of HER2 gene amplification.”
Lynette Summerill is an award-winning writer who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues, she writes a blog, Nonsmoking Nation, which follows global tobacco news and events.