Diagnostic Imaging
October 2003

X-RAY VISION

Virtual colonoscopy brings opportunity and obligation

Radiology should lead the way in screeening for prevention of colon cancer

By: John C. Hayes, Editor

It's time for radiology to step up to the plate and strongly promote CT colonoscopy as a screening tool for the prevention of colon cancer. As our cover story this month demonstrates, virtual colonoscopy is no longer an academic effort but something that is within the reach of many radiology practices. They should put this important new tool to use.

Although Medicare has reimbursed screening for colon cancer since 1997, it remains the second leading cause of cancer deaths in the U.S. and the most common cause of cancer deaths among nonsmokers. This year, it is estimated that 147,000 new cases of colorectal cancer and 57,100 deaths will occur.

Ever since the 1990s, radiology and gastroenterology have bickered over colon cancer screening. In 1997, radiology won an important victory in getting double-contrast barium enema endorsed and funded by Medicare as a screening test for colon cancer. Unfortunately, the DCBE scan, which even then was losing support within radiology, failed to catch on and the gastroenterologists were left with a clear field for optical colonoscopy, which is today the dominant method for a whole-colon screening exam.

But optical colonoscopy, even with its relatively high accuracy, also has failed to catch on. Concerns about the requirement for sedation, the discomfort, and the safety profile, combined with embarrassment and some degree of fear, have depressed enthusiasm for the procedure. One result is a lackluster screening rate (39% to 44% for endoscopic exams, according to the CDC) among the 50-and-over population that should be getting screened.

With virtual colonoscopy, radiology has a chance to boost that screening rate and improve the health of middle-aged and elderly Americans. Here's why:

  • Radiology has the tools and the infrastructure. Widely available and sophisticated multidetector CT scanners and computerized viewing programs are making CT colonoscopy scans faster and easier to interpret. Accuracy in the hands of a skilled radiologist is now equal to what is possible with optical exams. New developments in the works, including imaging agents that minimize difficulty and discomfort in bowel preparation, stand to make the process even easier for patients.

  • Radiology has the public perception. As uncomfortable as many people are with the idea of optical colonoscopy, no such hesitation greets virtual imaging with CT. In fact, noninvasive imaging procedures have a high-tech patina that many find attractive, and it could reach those who are skipping all screening exams right now. CT dose remains a concern, but this can be addressed with low-dose strategies.

  • Radiology has a practice strategy that makes sense. Virtual colonoscopy is a less invasive and more comfortable screening procedure than optical colonoscopy. If pathology is found, the patient can proceed to the optical exam and polypectomy, which can be performed more efficiently with guideposts established by the CT scan. For the majority among whom no pathology is found, the virtual exam offers a much better option.

    Some big issues remain. Consensus has yet to be reached on which polyps need to be excised, clouding the referral picture. Also, CT colonoscopy is not yet approved for Medicare payment, and many insurers take the same position. Those exams that are performed are under clinical trial or private pay situations.

    But these issues can be resolved, and should be, because virtual colonoscopy has too much recommending it to be left on the sidelines while screening rates remain suboptimal and death rates high. Radiologists and their professional associations need to do everything they can to make CT colonoscopy a central and integrated part of colon cancer prevention.