Researchers from the Lester and Sue Smith Breast Center at Baylor College of Medicine have uncovered new information about the genetic alterations that may contribute to the development of a subtype breast cancer typically associated with more aggressive forms of the disease and higher recurrence rates. The study, led by Dr. Xiaosong Wang, assistant professor of medicine – hematology and oncology and of molecular and cellular biology at Baylor, was published today August 7, 2014 online in Nature Communications and focused on the more aggressive molecular subtype of the estrogen-receptor positive breast cancer known as luminal B breast cancer. "While expressing the estrogen receptor, the luminal B breast cancers usually have higher tumor grade, larger tumor size, and poor prognosis, with most cases difficult to treat by endocrine therapy," said Dr. Wang, the lead and corresponding author on the report. "We wanted to gain a deeper understanding about the genetic alterations underlying this particular form of breast cancer, because we do not know about what malfunctions potentially cause this form to be more aggressive." In the study, Dr. Wang and colleagues identified a particular gene fusion on the estrogen receptor itself (hybrid gene formed from two previously separate genes) that was preferentially present in a subset of samples of tumors that were luminal B and ER-positive. The fusion was a result of rearrangements in the estrogen receptor gene called ESR1 (image depicts ESR1 protein) and another neighboring gene called CCDC170, Dr. Wang said. The findings were based in part on data available through the National Human Genome Research Initiative's Cancer Genome Atlas project. Rearrangement in the genes causes the disruption of the transfer of information.Login Or Register To Read Full Story