Study Indicates Breast Cancer Diagnosis is More Accurate with New Genomic Tests

The latest generation of genomic tests for breast cancer can improve physicians' ability to diagnose the disease and more precisely tailor each patient's treatment, according to a study being presented at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium (SABCS). The study examined the first commercially available genomic tests to determine the molecular subtype of a breast cancer tumor.

Researchers concluded that these relatively new genomic tests can more accurately classify breast cancer tumors. That in turn can help doctors better predict what type of treatment is best for that cancer subtype.

Genomic testing is part of the revolution in personalized medicine. It uses a patient's tumor genomic profile and other information to individualize treatment with the goal of better clinical results and overall cost savings. Genomic tests examine tumor tissue and the activity of groups of genes within the tumor, to provide a more comprehensive view of the cancer and treatment options. The study findings also suggest that some breast cancer patients who are currently prescribed chemotherapy after surgery may be able to avoid that therapy and its risks.

"We now have a better tool for determining which patients do not need to undergo treatments such as chemotherapy, when that treatment would be expensive and would not be useful to that particular patient," said medical oncologist Massimo Cristofanilli, M.D., FACP, lead author of the study and chief of the breast service line at Fox Chase Cancer Center, in Philadelphia.

Chemotherapy risks include immediate side effects, discomfort, and long-term damage, including a possible second cancer. Several studies have concluded that chemotherapy provides no real benefit for many breast cancer patients because of their cancer subtype and low risk of recurrence.

"These research findings contribute to our understanding of how cancer grows and how that growth can be stopped, and the findings will help us treat more patients more successfully," said Stefan Gluck, M.D., Ph.D., FRCPC, a medical oncologist at the University of Miami.

With the new genomic tests, physicians will be able to more precisely employ the sophisticated treatments that have been developed for breast cancer, said Dr. Cristofanilli: "Our sophisticated therapies mean nothing if we cannot apply them to patients appropriately. This newer panel of genomic tests enables us to better classify patients. That will help improve outcomes, because we will be more precisely applying the right treatment to the right patient."

Breast cancer tumors have traditionally been classified using so called immunochemistry (IHC) and fluorescent in-situ hybridization (FISH) techniques. The San Antonio study compared the accuracy of IHC and FISH results to two genomic tests (MammaPrint® and BluePrint™, part of the Symphony™ panel of genomic tests). Dr. Cristofanilli and study co-authors retrospectively analyzed 208 tumor samples from breast cancer patients whose age, survival and cancer pathology findings were known. Median follow-up on those 208 patients was 11.3 years

The study compared the accuracy of the genomic tests to the IHC and FISH tests that were done at the time each patient had been diagnosed. Researchers concluded that the new genomic tests provided a more accurate method for determining a patient's disease subtype, which helps establish a patient's risk of breast recurrence and identify the most appropriate adjuvant therapy.

"One message is that we cannot any longer afford to use the older methods alone for breast cancer prognosis and treatment planning," said Dr. Cristofanilli.

Study co-author Katharine Yao, MD., a breast surgeon at NorthShore University HealthSystem, in Evanston, Ill., said the San Antonio study findings could influence the guidance that physicians give their breast cancer patients. "This information can help doctors determine who the best candidates are for neoadjuvant therapy," she said. Neoadjuvant chemotherapy is sometimes used to shrink a tumor prior to its removal by surgery. "The study can also help breast surgeons better inform their patients about what type of tumor they have and how they can best move on to their treatment," she said.

The National Cancer Institute estimates that in the U.S. in 2012, 226,870 women will be diagnosed with and 39,510 women will die of breast cancer. The SABCS conference is Tuesday, Dec. 4 to Saturday, Dec. 8.