"We hope these findings will have the ability to identify people at increased risk for colon cancer, follow them closely and prevent disease or at least catch it early, similar to the approach doctors use in identifying patients at risk of heart disease," says Andrew P. Feinberg, M.D., King Fahd Professor of Medicine in the Kimmel Cancer Center at Johns Hopkins.
At present, the genetic marker blood tests are for research purposes only, Feinberg emphasized. "More efficient tests will take several more years at least to develop," said Feinberg, who with Hengmi Cui, Ph.D., and Marcia Cruz-Correa, M.D., Ph.D., led the study. "We also need to follow patients over time to see if they develop cancer after the test is positive," he added.
Prior research at Hopkins and elsewhere has identified genetic mutations linked specifically to hereditary forms of colon cancer. The genetic information uncovered in this study applies to the much more common forms of colon cancer that occur sporadically among the general population. An estimated 155,000 cases are diagnosed annually in the United States.
Earlier work also by the Feinberg team has shown that a form of gene silencing called loss of imprinting (LOI) in a growth-promoting gene called IGF2 (for insulin like growth factor) is one of the first genetic defects that happen in up to 40 percent of colon cancers. In the new study, the researchers found IGF2-related LOI present in blood samples as well as in colon tissue.