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With Competing Technologies and a Provocative Press, Will Colonoscopy Remain the Gold Standard for Colon Cancer Screening?

By Monica J. Smith

Reprinted from Gastroenterology & Endoscopy News March 2009; Volume 60, Number 3, Pages 1, 8, 11, 15.

New York - Kicking off just days after the Annals of Internal Medicine published an article on the discrepancy between the identification of left- and right-sided colon cancers with colonoscopy, the 2008 annual meeting of the New York Society for Gastrointestinal Endoscopy (NYSGE) was abuzz with the latest negative publicity surrounding colon cancer screening. Indeed, the Florence Lefcourt State of the Art Lecture, entitled “Future Directions for Colonoscopy,” could not have been more timely - what can gastroenterologists do to improve the effectiveness and efficiency of colonoscopy?

“There have been a whole series of papers in the news starting six months ago, with papers raising concerns about finding flat polyps, articles about CTC [computed tomographic colonography] and the Annals study suggesting there is a problem with missed right-colon lesions,” said Jonathan Cohen, MD, who delivered the lecture at the NYSGE meeting.

However, his talk paid little heed to the potential fallout from the provocative publicity; rather, it centered on what can be done to decrease the incidence of colorectal cancer and keep colonoscopy the gold standard for screening.

“In some respects, all these papers are good because they heighten the attention focused on colon cancer prevention, and they also heighten the focus on quality - doing a good exam and finding the polyps you need to find,” said Dr. Cohen, clinical professor of medicine, New York University School of Medicine, New York City. “We can do a better job with our preparation, and we can detect more lesions by going more slowly or using new technology.”

Complete polyp resection is another factor that contributes to the overall success of screening colonoscopy. “Some of the cancers that occur within screening intervals might be from incompletely resected polyps,” Dr. Cohen explained. “The idea of being able to see the edges very clearly so that we make sure we get whole polyps out is an important concept, and another way the new technology may have some role” (see sidebar “Technologic Improvements Could Make Colonoscopy Easier To Perform, More Effective”).

Full polypectomy at the time of detection is the signature advantage of colonoscopy, added Dr. Cohen, “and we need to continue to look for cost-effective ways to improve on what we do.”

Good record keeping is also important; it not only provides data for comparison with alternative screening methods, but also has an effect on performance.

“Keeping track of how well we’re doing, I believe, actually makes us better,” Dr. Cohen said. “For example, a number of studies have shown that withdrawal time goes up just by virtue of the fact that you’re keeping score” (e.g., Weiser KT et al. Gastrointest Endosc 2008;67:AB78. Abstract 242a).

In the relatively near future, Dr. Cohen predicts that colonoscopy will become easier to perform as a consequence of technologic advances, that the cost-effectiveness of other screening modalities will improve and that sedation costs will become increasingly relevant.

“There are still people who are not getting screened, and I think that’s one thing that’s driving technology and other options - trying to find ways to make exams more attractive or easier to do,” Dr. Cohen said. “It’s not just technologic advances but also innovation in process - two elements - that are going to be important.”
A Better, Cheaper Colonoscopy

Given the astronomic cost of cancer treatment, it seems a no-brainer that a therapeutic screening method would have to be quite costly to be considered too expensive compared with the alternative. Nonetheless, cost-effectiveness is a constant drone in many areas of health care, and screening colonoscopy is no exception. For example, a recent paper suggests that the current guidelines used to identify patients for colorectal cancer screening are “relatively inefficient in excluding a clinically meaningful [colorectal cancer] risk for patients in whom colonoscopy is generally not indicated” (Hassan C et al. Clin Gastroenterol Hepatol 2008;6:1231-1236).

According to Sidney Winawer, MD, Paul Sherlock Chair in Medicine, Memorial Sloan-Kettering Cancer Center, New York City, almost all colorectal cancer screening modalities are cost-effective.

“Many papers show the cost-effectiveness of FOBT [fecal occult blood testing], colonoscopy and flexible sigmoidoscopy. Some studies show one to be more cost-effective than another, but they’re all basically cost-effective,” Dr. Winawer said, pointing out that the cost-effectiveness of CTC depends on the size of the polyp referred for colonoscopy and the cost-effectiveness of fecal DNA testing depends on the interval between examinations.

As scrutiny of health care costs increases, technologic advances that render colonoscopy more cost-effective would likely make the procedure more attractive in the eyes of all beholders.

“Technology will likely make the passage of the scope from one end to the other easier to do; a number of companies are working on making this an easier process,” said Dr. Cohen. “If the exam is easier, it may be possible to do the exam with less sedation, or ultimately no sedation, eliminating another part of the cost.” Furthermore, it is possible that future easy-to-pass colonoscopes could be inserted by physician extenders, freeing endoscopists to attend to multiple rooms at the same time.
Although interest has been shown in endoscope development, few new instruments are yet in wide use.

“None of this has really become mainstream yet,” Dr. Cohen said, pointing out that the drive behind this type of development is the desire to increase the ability of doctors to reach the cecum, which most already do. “Most gastroenterologists are getting to the cecum 95% to 98% of the time, so that is not as big a clinical problem.”

Improvements in optics, however, could facilitate optical diagnosis. This may improve the cost-effectiveness of colonoscopy by limiting the need for pathologic interpretation.
“If endoscopists are able to accurately characterize the lesions encountered, they can perhaps remove small polyps and not have them analyzed. Once they’re removed, they can’t cause any damage, and future screening intervals would be determined by the optical diagnosis,” Dr. Cohen said.

“It seems the learning curve is pretty quick to get up to reasonable accuracy in terms of identifying a lesion as a hyperplastic polyp or an adenomatous polyp,” Dr. Cohen said, citing an accuracy rate for the detection of advanced adenomas and cancers of approximately 90%. The physician would then be able to accurately assess when the patient should have his or her next surveillance examination. “That’s the major function of pathology for these small lesions.”

However, all of these potential technologic advances would need to be studied for their ability to improve cost-effectiveness. “We need to know if they do actually lead to safe and effective reductions in cost that will make the procedure more cost-effective and more attractive in that regard compared to alternatives,” Dr. Cohen said.

CTC - How Big Is the Threat?

Although CTC has received a lot of attention in medical journals and the lay press, a number of drawbacks may keep it from truly competing with colonoscopy.
For one thing, although the ability of CTC to detect 90% of significant polyps has been interpreted positively by both professional journals and the lay press, in Dr. Cohen’s opinion, the glass is 10% empty.

“For a large population, it seems fairly obvious that [CTC] would miss a lot of cancers.” He suspected that patients would not be comfortable with a test that could miss one of every 10 significant polyps.

Then there’s the debate over what to do with small polyps detected by CTC and other diagnostic-only screening methods. One study suggests that the removal of polyps that are 6 to 9 mm in diameter is costly and inefficient, and that patients with these types of polyps should undergo three-year follow-up surveillance (Pickhardt PJ et al. AJR Am J Roentgenol 2008;191:1509-1516).

This approach may be cost-effective, but Dr. Cohen pointed to a study showing that one in 15 asymptomatic patients whose largest polyp is 6 to 9 mm in diameter will have advanced histology (Lieberman D et al. Gastroenterology 2008;135:1100-1105). Furthermore, another study suggests that the “wait-and-see” approach is likely to result in more cancers and deaths than immediate colonoscopy and polypectomy (Hur C et al. Clin Gastroenterol Hepatol 2007;5:237-244).

“Another theoretical concern with CTC is the difficulty of locating lesions discovered by a diagnostic-only method—a small polyp detected on CTC might be difficult or impossible to find during a subsequent colonoscopy. This would make the colonoscopy a good deal more difficult to perform,” Dr. Cohen said.
The Future Is Now

Regardless of the potential of new technologies to improve polyp detection, gastroenterologists already have what they need to perform quality bowel examinations.
“We know that if screening colonoscopy is done and an adenoma is found and removed, there will be a reduction in the incidence of colon cancer,” Dr. Winawer said. “Right now, we have all the techniques that are necessary to do a good screening colonoscopy in a community: to find polyps, remove them, reduce the incidence of colon cancer and reduce the mortality.”

Ultimately, even the most careful screening colonoscopy will be compromised if bowel preparation is inadequate, which it is in approximately one-fourth of U.S. patients. Poor bowel preparation leads to longer examination times, with fewer polyps detected. In some cases, repeat colonoscopy is required, further driving up costs.
“None of the technologic advances I discussed are even applicable unless the patient has had adequate prep,” Dr. Cohen said. “And that’s why we can’t separate the advances in technology from improvements in our process.” Split dosing of bowel preparations seems to improve results; the closer the last dose of solution is taken before the examination, the better.

One useful interpretation of the Annals study is that problems can occur when colonoscopy is performed by endoscopists who are not highly experienced and skilled in the procedure. However, well-trained and diligent endoscopists are fully capable of performing high-quality examinations every time.

“If the cecum was reached each time, and the withdrawal time was slow and a good examination was done, we could right now achieve a tremendous reduction in the incidence and mortality of colorectal cancer,” Dr. Winawer said.

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