Genetic testing of mitochondrial DNA could reveal otherwise unknown ancestry that can influence a person’s risk for certain types of breast cancer, a new study finds. University of Texas (UT) Southwestern Medical Center cancer researchers studying mitochondrial DNA (mtDNA) in a group of triple negative breast cancer patients found that 13 percent of participants were unaware of ancestry that could influence their risk of cancer. “We found 12 differences among 92 patients, a significant amount,” said lead author Dr. Roshni Rao, Director of the George N. Peters, M.D. Center for Breast Surgery at UT Southwestern. “Some patients who self-identified as Hispanic had African-American ancestry. One Hispanic woman was found to be Ashkenazi Jewish. Both African Americans and some Ashkenazi Jewish populations have a higher risk for triple negative breast cancer,” said Dr. Rao, Associate Professor of Surgery and with the Harold C. Simmons Comprehensive Cancer Center. Triple negative breast cancer is characterized by tumors that do not express receptors for estrogen, progesterone, or Her2-Neu, and accounts for about 15 to 20 percent of all breast cancer cases. This form of the disease is known to be particularly aggressive, and challenging to treat. Patients with triple negative breast cancer have a higher incidence of metastatic disease – cancer spreading to other parts of the body – and an overall higher rate of death from breast cancer, compared to patients with other types of breast cancer. “This study is the first to perform mtDNA testing for self-described African-Americans, Caucasians, and Hispanics with triple negative breast cancer and to identify unexpected mtDNA patterns,” said senior author Dr. Barbara Haley, Professor of Internal Medicine, who holds the Charles Cameron Sprague, M.D. Chair in Clinical Oncology.
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