2011-04-08 05:57:22 UTC

Post-Colonoscopy Era Ahead? Not Immediately

April 8, 2011


John B. Marshall, MD, AGAF

Professor of Medicine, Division of Gastroenterology, University of Missouri School of Medicine, Columbia


The familiar quote, “The report of my death was an exaggeration,” by my fellow Missourian, Mark Twain, is apropos to my premise, namely that reports of us entering a post-colonoscopy era are premature. Colonoscopy, with its ability to remove polyps and to take biopsies, will endure for a long time. Colonoscopy has also been the dominant colorectal cancer (CRC) screening modality over the past decade, though its dominance will be challenged in coming years. Even if other screening modalities come into use, colonoscopy will still be a part of managing their positive results.

Though optical colonoscopy has set a high standard as a CRC screening technique, it is not perfect, if for no other reason than its invasiveness. Problems include the need for IV sedation in most patients, infrequent serious complications (particularly perforation) and the need for most patients to miss a day of work.

It is inevitable that some other less invasive, preferably non-invasive, modality will eventually take over. However, it remains unclear what that modality (or modalities) will be and how soon it (they) will take over. Consequently, the future of screening colonoscopy and overall colonoscopy procedure volumes is difficult to predict as we consider the next three to seven years.

CTC, the next challenger to colonoscopy’s dominance

Though CT colonography (CTC) would seem to be the next major challenger in the CRC screening arena, its widespread incorporation into practice has gone slower than many had anticipated. There are a number of reasons for this:

  • CTC is highly operator dependent.
  • Serious questions remain regarding management of polyps less than 10 mm.
  • CTC fails to detect flat polyps.
  • There are risks of radiation exposure.
  • Questions remain on how to handle incidental extracolonic findings.
  • There is a current need for full bowel preparation.
  • The test is performed without sedation and can be painful because of the need to distend the colon.
  • It is not clear that CTC will improve CRC screening adherence rates over those seen with colonoscopy.

In most studies, small polyps (less than or equal to 5 mm) have not been reported because of poor accuracy of CTC for polyps of this size and the low prevalence of advanced neoplasia in diminutive polyps. However, the ethics of not reporting these polyps is still a matter of debate, particularly when there are three or more. The American College of Radiology recommends the reporting of polyps greater than or equal to 6 mm found on CTC.1 However, the management of medium-sized polyps (6 to 9 mm) is contentious. It has been a common practice of radiologists to recommend repeating CTC in three years rather than referring the patient for colonoscopic polypectomy.2, 3 This carries risks in terms of CRC development, the potential of losing patients to follow-up, cost and radiation exposure.2

Management of 6 to 9 mm polyps found on CTC has several implications. First, we have little information to know if CTC follow-up of such polyps is effective in preventing CRC. Second, the polyp threshold size for referral for colonoscopy is a major factor determining whether CTC is a cost-effective screening modality — the smaller the polyp size prompting referral, the less the cost effectiveness. Third, the selection of threshold size for referral for colonoscopy (6 mm versus 10 mm) has large implications on the volume of patient referrals for colonoscopy if and when CTC becomes a widely used screening test. In one American study reported by Schwartz et al., which looked at the impact of a CTC screening program on colonoscopy in clinical practice and utilized a threshold of greater than or equal to 10 mm (or three or more polyps 6 to 9 mm), only 8 percent of those screened with CTC were referred for colonoscopy.4 However, this study found no decrease in the total number of colonoscopy exams or the number of screening colonoscopies performed during the study period. Utilizing a threshold size of greater than or equal to 6 mm would result in a much greater colonoscopy referral percentage.

Post-colonoscopy era coming?

Can we expect an era in the next few years where screening colonoscopy might vanish? At some point, CMS will likely approve payment for CTC as a screening test for CRC. Theoretically, at that point, the number of colonoscopies could drop precipitously if CTC quickly became the dominant screening test and if the threshold size of polyps prompting referral for colonoscopy is 10 mm. However, it is unclear how rapidly CTC would be incorporated into practice or how rapidly referrals for screening colonoscopy would decrease. The study by Schwartz et al. suggests that colonoscopy numbers may not decline as much as projected.4 Also, CTC is less invasive than colonoscopy, but definitely not non-invasive. Having one’s colon distended with air or CO2 while unsedated is not fun. It remains to be seen how accepting Americans will be of this. And will they be willing to have a repeat CTC every three to five years? But, while I think screening colonoscopy will hang in longer than many think, we cannot expect screening colonoscopy, in its present form, to be with us forever.

We have to expect change

Over at least the past decade, businesses, employees and students graduating from college have been constantly reminded that in our 21st century world, they will need to periodically re-invent themselves to remain successful. Should we as gastroenterologists expect it to be any different? When I first learned to perform colonoscopy during my fellowship from 1980 to 1982, colonoscopy practice was just starting to explode. Barium contrast studies of the upper and lower GI tract were still widely done, but their use steadily fell to a trickle. Now, radiographic colonic imaging is poised for a comeback. However, the pendulum could swing back to GI if capsule colonoscopy is eventually shown to be an effective screening tool.

Unfortunately, our current GI practice model is dominated and funded largely by screening colonoscopy to the detriment of many other aspects of endoscopic and GI practice. As stated, this cannot go on forever. Recently, Banerjee and Pasricha put it aptly that it’s time for us to better diversify our GI practice portfolios in order to minimize the financial risks to our practices.5

The future of gastroenterology, post-colonoscopy

Rather than contemplating “the future of endoscopy, post-colonoscopy,” I think it is better to look at “the future of gastroenterology, post-colonoscopy.” The threat of an end of screening colonoscopy actually has the potential to be a blessing in disguise. For one thing, gastroenterologists need to be more aggressive in pursuing innovation and advancing evolving technologies.5, 6 Endoscopic submucosal dissection, for instance, will become an increasingly important alternative to colectomy for the management of lateral spreading tumors. It is much more demanding from a technical and time standpoint compared to standard polypectomy. Will gastroenterologists or surgeons be the future practitioners? What about Natural Orifice Translumenal Endoscopic Surgery®, an area with significant turf barriers and uncertainty regarding adequate training? Unless we get more aggressive quickly, we will miss the boat. Many other innovative procedures are being introduced for the motivated, talented and properly trained gastroenterologist. How many endoscopists will want to master increasingly complex endoscopic procedures remains a question. Restoration of the cognitive aspects of gastroenterology will also be important in the future.7 Ultimately, we must change the way we train our future gastroenterologists to emphasize both the cognitive aspects and innovation, particularly in a multidisciplinary approach.


The future of colonoscopy volumes is uncertain, though the numbers may not drop off over the next five years nearly as much as some have projected. However, we know that (a) screening colonoscopy for the entire adult population in its present form cannot endure forever and (b) the need to periodically re-invent ourselves and our profession is certain. Basketball coaching legend John Wooden said: “Failure is not fatal, but failure to change might be.” We need to be more proactive and aggressive in transforming our practices. It is a time for dynamic and visionary leadership in our professional societies, particularly given the economic realities that confront us. Young gastroenterologists have much to consider as they plan out their careers.


1. McFarland EG, Fletcher JG, Pickhardt P, et al. ACR Colon Cancer Committee White Paper: Status of CT colonography 2009. J Am Coll Radiol 2009; 6: 756-772.

2. Rex DK. Colonoscopy: The dominant and preferred colorectal cancer screening strategy in the United States. Mayo Clin Proc 2007; 82: 662-664.

3. Schoen RE, Hashash JG. Con: CT colonography—Not yet ready for community-wide implementation. Am J Gastroenterol 2010; 105: 2132-2137.

4. Schwartz DC, Dasher KJ, Said A, et al. Impact of a CT colonography screening program on endoscopic colonoscopy in clinical practice. Am J Gastroenterol 2008; 103: 346-351.

5. Banerjee S, Pasricha PJ. Embracing new technology in the gastroenterology practice. Clin Gastroenterol Hepatol 2010; 8: 848-850.

6. Barkun A, Ginsberg GG, Hawes R, et al. The future of academic endoscopy units: challenges and opportunities. Gastrointest Endosc 2010; 71: 1033-1037.

7. Friedman LS. Cognitive GI must be resurrected. AGA Perspectives 2010; 6: 4-6.


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