Cornell University researchers have discovered a likely origin of epithelial ovarian cancer (ovarian carcinoma), the fifth leading cause of cancer death among women in the United States. Pinpointing where this cancer originates has been difficult because 70 percent of patients are in advanced stages of disease by the time it is detected. Because the origin of ovarian carcinoma development is unknown, early diagnostic tests have so far been unsuccessful. Some epithelial cancers are known to occur in transitional zones between two types of epithelium (layers of tissue that line the body and organs and form glands), while others originate in epithelial tissue stem cells. Many organs have the capacity for regeneration, which is done by adult stem cells located in areas of each organ called stem cell niches. With this knowledge, the researchers discovered a novel stem cell niche for the ovarian surface epithelium in mice and showed that ovarian carcinoma preferentially originates from stem cells found in that niche, according to the study published online on March 6, 2013 in Nature. This stem cell niche lies in a transitional area known as the hilum region, a layer of cells that links the ovary to the rest of the body. "We now know where these cells are located in mice, so we can look in humans in those areas," said Dr. Alexander Nikitin, professor of pathology, leader of the Cornell Stem Cell Program and the Nature paper's senior author. Dr. Andrea Flesken-Nikitin, a postdoctoral researcher in Dr. Nikitin's lab, is the paper's lead author. The findings also provide a guide for scientists to look for stem cell niches and sources of cancer in other transitional zones in other organs, Dr. Nikitin added.Login Or Register To Read Full Story