Researchers at the National Institutes of Health and the University of Hong Kong have discovered that high levels of a particular protein in cancer cells are a reliable indicator that a cancer will spread. By measuring the protein’s genetic material in tumors that had been surgically removed from patients, along with measuring the genetic material from surrounding tissue, the researchers could predict at least 90 percent of the time whether a cancer would spread within two years. The findings raise the long term possibilities of new tests to gauge the likelihood that a cancer will spread and, ultimately, of a treatment that could prevent cancer from spreading. The protein, known as CPE-delta N, is a form of carboxypeptidase E (CPE). Ordinarily, CPE is involved in processing insulin and other hormones. CPE-delta N, a variant of CPE, was present in high amounts in tumors that had spread and, to a much lesser degree, in surrounding tissues. Cancer cells can break away from a primary tumor and spread, or metastasize, to other parts of the body, where they form new tumors. Metastatic cancer is often fatal, and health care practitioners seek to contain cancer early, before it can metastasize.