Possible genetic flag for brain cancer
Defects in two IDH genes appear unique to certain brain tumors, although the genes’ role is unclear
By Nathan Seppa
Mutations in two genes, IDH1 and IDH2, might provide markers that enable doctors to discern malignant from benign brain tumors and catch some cancers early, scientists report in the Feb. 19 New England Journal of Medicine.
The study adds to a growing list of molecular clues that doctors may ultimately use to diagnosis and treat cancers, says study coauthor D. Williams Parsons, a pediatric oncologist and Howard Hughes Medical Institute investigator at Johns Hopkins University in Baltimore.
Doctors diagnose nearly 200,000 brain cancers each year in the United States. Most get their start elsewhere in the body and spread to the brain. But in about 22,000 of these patients, the cancer originates in the brain or central nervous system. These primary brain tumors are most often gliomas — clusters of tumor cells that derive from the brain’s glial cells. Gliomas vary in virulence from benign (grade 1) to fast-growing and rapidly lethal (grade 4).
The IDH genes are so-named because they encode an enzyme called isocitrate dehydrogenase. While the role of the enzyme is poorly understood, the mutations in IDH genes attracted interest after turning up last year in brain tumors but not in other cancer tissues. In the new study, the researchers tested samples of benign and cancerous primary brain tumors removed from 445 people and from tumors obtained from 494 others who had cancers of the colon, prostate, pancreas, breast, stomach, ovary or blood (leukemia).