Study Finds Virtual Colonoscopy
Spots More Than Colon Cancer

Virtual colonoscopy can spot cancers and growths beyond the colon because it takes a picture of the entire abdominal cavity and pelvis, a new study says.

That means that, besides detecting colorectal cancers, a virtual colonoscopy can find cancers and other "clinically important" conditions that would be missed with standard colonoscopy. And this can be done at very little additional cost, the study researchers added.

Virtual colonoscopy -- called computed tomographic colonography -- is a noninvasive screening method for detecting colon cancer. It uses a series of images to visually reconstruct the interior of the colon on a computer. Unlike standard colonoscopy -- an invasive procedure that looks only at the interior of the colon -- virtual colonoscopy sees surrounding areas of the lower torso as well.

While the U.S. Food and Drug Administration has approved virtual colonoscopy, some doctors and physicians' groups have been slow to embrace the technology because they don't think it's as reliable as a standard colonoscopy.

"This is a test that is being proposed for colorectal cancer screening," said lead researcher Dr. Judy Yee, chief of radiology at the Veterans Affairs Medical Center and an associate professor and vice chairwoman of radiology at the University of California, San Francisco School of Medicine. "But it can detect significant findings outside the colon as well."

Yee's report appears in the August issue of Radiology.

Yee's team performed virtual colonoscopies on 500 male patients, with a median age of 62.5 years, and then evaluated the incidences of "extracolonic findings" -- potential health problems outside the colon. Of these patients, 315 had "extracolonic findings," and 45 patients of them had "clinically important" ones. They included large aneurysms, suspicious lesions and masses in the solid organs of the abdomen, as well as thickening of the gallbladder wall, among other problems, the researchers reported.

The additional cost per exam to look for these conditions was $28.12, the researchers said.

Yee sees the study as another step toward broader acceptance of virtual colonoscopy as a screening tool for colorectal cancer.

"We are hoping to develop virtual colonoscopy as a noninvasive technique to screen the colon so that we can bring more people in for screening," Yee said. "Currently, less than 30 percent of individuals in this country come in for colon cancer screening."

Virtual colonoscopy should be a viable option for colorectal cancer screening, Yee said, adding, "It has an added advantage over colonoscopy in that it can look outside the colon."

One expert thinks this study offers more evidence of the value of virtual colonoscopy.

"This study reminds us the virtual colonoscopy is a CT scan of the whole abdomen and pelvis," said Dr. Joseph T. Ferrucci, chairman of department of radiology at Boston University School of Medicine. "This is a potential additional indication for approving computed tomographic colonography for screening."

Ferrucci believes virtual colonoscopy could replace standard colonoscopy for detecting colon cancer. "Yee's data adds to the argument to have an imaging test rather than invasive colonoscopy. Computed tomographic colonography, right now today, is a viable alternative to colonoscopy," he said.

However, another cancer expert doesn't think Yee's study adds anything to the debate over virtual colonoscopy as a screening tool.

"The question is: Is anyone helped by all this?" said Dr. Herman Kattlove, a medical oncologist and spokesman for the American Cancer Society. "The answer is they [Yee's research team] didn't help anyone."

To see if detecting these additional problems has any merit, one would have to do a study to see determine the benefit, Katllove said. "When you do little studies like this, you may find something that's treatable, but before anyone rushes to recommend this, you really have to do a clinical trial to see if it makes a difference in patient mortality or even quality of life."

Another study in the same issue of the journal found that using magnetic resonance spectroscopy to measure biochemical changes in breast tumors lets radiologists more accurately distinguish benign tumors from cancerous ones.

"Spectroscopy gives us an additional piece of information about the biochemical composition of the tumor," study author Michael Garwood, associate director of the Center for Magnetic Resonance Research at the University of Minnesota, said in a prepared statement. "When the standard MR imaging exam is inconclusive, the spectroscopy measurement can improve the rate of detecting a cancerous breast tumor."

Reference Source 101
August 4, 2005

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