CT colonography experts plan for growing demand

Academic radiologists who helpedinvent CT colonography are urging their community-based colleagues to gear up for a possible jump in public demand for CTC following the American Cancer Society's decision in March to add the procedure to its list of preferred colon cancer screening options.

"This is a new day for CTC," said Dr. Judy Yee, vice chair of radiology at the University of California, San Francisco. "The guidelines recognize a lot of the science. The ACRIN 6664 colonography trial created huge momentum to get CTC out there to the public."

Released in late 2007, outcomes from that trial found that CTC is equivalent to standard colonoscopy for screening intermediate- and large-sized polyps.

The ACS guidelines recommended CTC as a preferred test along with flexible sigmoidoscopy and double-contrast barium enemas to screen for cancerous polyps every five years. Colonoscopy was recommended as an alternative performed every 10 years. The exams were recommended for all men and women beginning at age 50 who carry an average risk of colorectal cancer.

The question of who should perform CTC has been the source of friction, and the guidelines may de-escalate some of that discord. Ideally, radiologists and gastroenterologists will continue to work together, but other circumstances may ultimately influence who performs CTC screening, Yee said. Local resources, expertise, and interest in performing the procedure should be taken into consideration.

"Obviously, radiologists developed the technique, and we receive our training in imaging. Gastroenterologists are the experts at looking at the colon lumen on colonoscopy," she said. "But I think gastroenterologists will be kept quite busy with referrals from the radiologists who perform CTC screening."

Proper training is a must, regardless of who conducts the exams, said Dr. Beth McFarland, chair of the American College of Radiology's colon cancer committee.

To that end, the ACR sponsored a course featuring the supervised interpretation of CTC in April. It is developing a certification process to recognize competence. The American Gastroenterological Association also offers CTC training.

CTC's developers are optimistic about the likely public response to the ACS endorsement, but no one has yet gauged the willingness of older adults to undergo the minimally intrusive procedure.

Raising the awareness of the public and general medical practitioners about the relative merits of the various colorectal cancer screening tests is key to gaining more acceptance, according to McFarland.

"It's not just a matter of doing CT colonography because it's less invasive than colonoscopy," she said. "It's a collaborative message to the community that there is an array of tests . . . and (that) different tests are better, depending on the patient's age, comorbidities, and symptoms."

-By Shalmali Pal