Scientists ID Leukemia Stem Cells

British scientists have identified the stem cells that cause the most common type of childhood leukemia, the Times of London reports. The unprecedented discovery means doctors can monitor cell levels in young cancer patients and stop treatment when those cells are gone, said a leading oncology expert. The work also could help scientists develop therapies targeting the specific cells.

Scientists discovered the cancerous link by studying 4-year-old twins—a girl with acute lymphoblastic leukemia and her healthy sister. Doctors found they both had genetically abnormal cells in their blood, but the girl with cancer had a second defect in her blood stem cells. It’s unclear what causes the initial genetic abnormality, but cancer experts are calling the research a major breakthrough. (More cancer stories.)