Ah-ha Moment Leads to New Breast Cancer Tumor Testing Standards - Mayo Clinic

In a front-page April 19 story, the New York Times describes the moment of truth that Dr. Edith Perez, a breast cancer oncologist and researcher at Mayo Clinic, Florida, had in 2001 about the quality of tests given around the world to newly diagnosed breast cancer patients. These tests are designed to assess what kind of tumors a woman has, based on proteins on the cancer. Correct treatment depends on that information. As the principal investigator of two large national studies of Herceptin for women with HER2 positive early-stage breast cancer, she knew that women were having these tests at all kinds of places, from community hospitals to major medical centers to central national labs that specialize in these tests. She wondered if the women entering her clinical trials based on a positive HER2 test actually did have that kind of cancer. So she decided to retest the tumor samples in a central lab to confirm the results. As the New York Times reported, the outcome stunned her and her colleagues. Twenty percent of the first 119 women whose initial tests indicated their tumors had excess HER2 turned out not to have it on retesting. That discovery set off alarm bells. Dr. Perez and many other researchers required that the tests be analyzed in central laboratories, including Mayos own, and they called for national standards to be in place to ensure all women received the best available analysis of tumor tests. That eventually happened the College of American Pathology and the American Society of Clinical Oncology dictated criteria for declaring a HER2 test positive or negative, and they required proficiency testing. On April 19 the same organizations released new guidelines for testing estrogen receptors (ER) on tumors. ER positive breast cancer is the most common type. Dr. Perez says that breast cancer samples for Mayo Clinic patients are examined in Mayos central laboratory, and the administration and the analysis of these tests, and the clinical decisions made from the results, are amongst the best that any institution can offer. Researchers at Mayo Clinic are in the forefront of identifying issues in these tests on a national basis, and conducting studies to improve patient identification for therapies and outcomes, she says. Our goal is to understand more about these tumors in order to improve the predictive power of these tests and, thus, improve the care we give to our patients.