Computerized tomographic colonography, also known as virtual colonoscopy, is comparable to standard colonoscopy in its ability to accurately detect cancer and precancerous polyps in people ages 65 and older, says a paper published online last month in Radiology.

This is consistent with results of the ACRIN clinical trials cooperative's national CT colonography trial, published in the New England Journal of Medicine in 2008. That trial demonstrated CT colonography can serve as a primary colorectal cancer screening option for adults ages 50 and older, researchers asserted, but it didn't break out data specifically for participants ages 65 and older included in the overall analysis.

The Centers for Medicare and Medicaid Services has deferred coverage for CT colonography, primarily citing a lack of data on the exam's performance in Medicare-eligible recipients ages 65 and older.

"Our goal in carrying out this secondary analysis was to determine if the accuracy of CT colonography to detect polyps of clinical concern in patients 65 and older is comparable to the test's accuracy for the 50 and over population studied in the 2008 ACRIN trial. We found no significant difference in the screening exam's performance between the two age groups," says Dr. C. Daniel Johnson, the paper's primary author who works at the Mayo Clinic in Scottsdale, Ariz., and is the principal investigator of the National CT colonography trial.

"CT colonography is a perfectly viable colorectal cancer screening tool for the traditional Medicare age population. Wider availability made possible by Medicare coverage of CT colonography would attract more seniors to be screened for colorectal cancer, which is so successfully treated when detected early. Making CT colonography more available to seniors ultimately could save lives," Johnson contends.

ACRIN is a National Cancer Institute clinical trials cooperative group. It's made up of investigators from more than 100 academic and communitybased medical facilities in the U.S. and several international institutions. Its mission is to develop information through clinical trials of diagnostic imaging and image-guided therapeutic procedures that will result in earlier diagnosis of cancer and allay the concerns of those who don't have cancer, while improving the length and quality of lives of cancer patients.

The group's National CT colonography trial recruited 2,600 study participants ages 50 and over from 15 U.S. medical centers to compare the accuracy of state-of-the-art CT colonography to the gold standard of conventional colonoscopy. Ninety percent of the polyps 1 centimeter or larger—the polyps most likely to become cancerous—were detected by CT colonography. Polyps as small as one-half centimeter also were detected by CT colonography with a high degree of accuracy.

In the secondary analysis of the 65-and-over cohort, data were available for 477 study participants. The percentage of participants with large polyps was significantly greater among the older participant group—3.7 percent for people younger than 65 years old compared with 6.9 percent for people older than 65.

ACRIN Chairman Dr. Mitchell J. Schnall, professor of research radiology at the University of Pennsylvania, says, "These results demonstrate the wealth of data that are collected in ACRIN clinical trials that can be used to explore important cancer screening and other research questions."

CT colonography employs virtual reality technology to produce a three-dimensional visualization that permits a thorough and minimally invasive evaluation of the entire colon and rectum, proponents assert. The ACRIN trial is said to be the largest multi-center study to compare the accuracy of CT colonography to conventional colonoscopy in patients 50 years old and older.

Colorectal cancer is the third most frequently diagnosed cancer and second leading cause of cancer death in men and women in the U.S. Yet, despite the known benefits of,24,29,30 screening, studies indicate that millions of Americans age 50 and older aren't being screened for the disease.