Visualizing Cancer: Images of Tumors Can Detect Gene Expression

Article excerpt

Radiologists have found a way to use X-ray scans to identify which genes in a tumor are active.

The ability to glean genetic information about tumors from routine medical imagery could increase the use of cancer therapies that target a tumor's genetic quirks. Targeted therapies promise better cancer treatments with fewer side effects than current approaches do. But doctors rarely profile a tumor's genes, in part because it's expensive to do and requires surgical removal of tissue.

"Genetic analysis of tumors is not usually done, but the first thing a doctor will do to a cancer patient is give them [an X-ray] scan, says Michael Kuo of the University of California, San Diego, a coleader of the study. The new technique infers gene activity from such scans and so "lets us see gene expression of a tumor in a noninvasive way."

The researchers looked at computerized tomography (CT) scans of liver tumors in 28 patients. CT scans use X rays to render virtual slices through a person's body. Kuo and his colleagues identified 32 visible features--such as a dark halo or a region with mixed textures--that at least two radiologists could independently identify as present or not.

The scientists also measured the activity of 6,732 genes to create genetic profiles of the tumors. Comparisons of these profiles with the occurrence of the visual features revealed strong correlations between profiles and sets of features.

With this system, Kuo and his colleagues could use a CT scan to deduce the activity of more than 80 percent of the profiled genes in each tumor. …