Cystic Fibrosis Colorectal Cancer Screening Consensus Recommendations

Denis Hadjiliadis; Alexander Khoruts; Ann G. Zauber; Sarah E. Hempstead; Patrick Maisonneuve; Albert B. Lowenfels


Gastroenterology. 2018;154(3):736-745. 

In This Article


The task force found limited information on CRC screening in adults with CF, and available reports consisted mostly of retrospective reviews of patient records and case−control studies. The task force identified no randomized clinical trials comparing results in screened vs nonscreened patients or reports comparing results of colonoscopy with results of less-invasive screening procedures.

The task force developed ten recommendations (Table 1). Based on the quality and limited number of studies, the recommendations represent the consensus opinion of the task force. All but 2 statements reached 100% agreement; recommendations 4 and 7 reached 94% agreement. The American Gastroenterological Association reviewed and agrees with the recommendations in this statement.

Results of Microsimulation Screening Analysis−colon Cancer Model for Colonoscopy

The Microsimulation Screening Analysis-Colon model predicted that in non-transplant CF patients, the optimal colonoscopy strategy was colonoscopy every 5 years between age 40 and 75 years. This strategy resulted in 44 extra years of life per 1000 CF patients screened at a net cost of $0.7 million compared to no screening. The incremental costs per life-year gained (LYG) compared to a similar strategy that ended screening at age 70 were $84,000 per LYG.[30]

For CF patients with an organ transplant, the optimal colonoscopy strategy was colonoscopy every 3 years from age 35 to 55 years. Age 55 years was utilized because of the small population of individuals over the age of 55 years. The recommendations below have no upper age limit. This strategy resulted in 56 extra life-years per 1000 patients screened at a net cost of $1.3 million compared to no screening. The incremental costs per LYG compared to colonoscopy every 5 years in the same age range were $71,000. However, the optimal colonoscopy interval was sensitive to the age of transplant (optimal interval of 5 and 10 years for organ transplant ages of 25 and 20 years, respectively, and beginning screening at 30 years). The task force additionally considered the modeling projection that 64 extra life-years were gained compared to no screening if colonoscopy was started at age 30 years. This more than doubled cost to $166,000 per LYG. Because transplantation is already an expensive and high-risk procedure, the committee judged that improving the likelihood of achieving the potentially high benefit by reducing deaths from CRC was consistent with the original intent to undergo transplantation. In both cohorts (organ transplant and non-transplant), the upper age limit was a result of a small number of individuals in these age groups rather than lack of efficacy based on modeling.[30]


1. The Cystic Fibrosis Foundation recommends that all decisions on colorectal cancer screening and surveillance in individuals with cystic fibrosis be based on shared decisions between the provider and individual with cystic fibrosis about treatment, comorbidities, safety, and quality of life. The decision to proceed with screening is more complicated in the CF population than in the non-CF population. The complexity arises from several issues: (1) although individuals with CF are at considerably higher risk of developing CRC than non-CF persons, all other factors being equal, the overall survival may be limited in certain subgroups of people with CF due to serious concurrent comorbidities;[32] (2) preparation for colonoscopy (see below) is more time-consuming in individuals with CF than in other populations;[18] (3) the risk associated with colonoscopy in the general population is low but may be increased in individuals with CF;[33] and (4) other modalities, such as FIT, which may be suitable for the general population, have not been evaluated in the CF population. Given these complexities, the task force members unanimously agreed that individuals with CF and their providers should engage in a shared decision-making process to carefully assess the risks and benefits of CRC screening and its impact on the health and quality of life for the adult with CF. Importantly, screening and surveillance recommendations presented in this manuscript were developed for asymptomatic CF patients. Physicians should recognize that CF is a colon cancer syndrome and consider diagnostic evaluation when patients present with new, suggestive symptoms or laboratory abnormalities.

2. The Cystic Fibrosis Foundation recommends that all colorectal cancer screening and surveillance for individuals with cystic fibrosis are jointly managed by cystic fibrosis health care professionals and an endoscopist. Ideally, colonoscopic screening is performed by a CF-trained endoscopist familiar with the multiple gastrointestinal challenges in the CF patient population. However, many CF Foundation−accredited care centers do not have a dedicated adult gastroenterologist. Individuals with CF are often referred to an endoscopist who may have limited experience in CF and may be unfamiliar with the unique preparation required for CRC screening. Further management may be provided by a gastroenterologist, endoscopist, and other care providers. To ensure CF-specific CRC screening issues are addressed, the task force recommends that close cooperation between the CF care provider and an endoscopist must precede and continue after completion of the CRC screening.

3. The Cystic Fibrosis Foundation recommends colonoscopy as the screening examination for colorectal cancer in individuals with cystic fibrosis. Recommendations for the method of screening differ depending upon the risk category of the person or group selected for screening[34] Colonoscopy, unlike other screening procedures, can detect as well as remove polyps. This is one of the main reasons why colonoscopy is the screening procedure of choice for other high-risk groups, for example, Lynch syndrome.[35] Similar reasoning applies to CF, which is another genetically determined high-risk group. In addition, there are no published data of utilization of other modalities in individuals with CF.

4. The Cystic Fibrosis Foundation concludes that the evidence is insufficient to recommend the use of computed tomography colonography, stool-based tests, or flexible sigmoidoscopy in individuals with cystic fibrosis for the purpose of colorectal cancer screening. The task force found no published evidence on the utility of any of these procedures in CRC screening for individuals with CF. Given the high prevalence of polyps in the CF population, the pretest probability of requiring a colonoscopy after any other type of screening procedure is high. Stool-based tests, such as FIT, or perhaps multi-targeted stool DNA testing, might be valuable as a first-line test, as suggested by the results obtained by modeling, but they have never been evaluated in the CF population. Until further data are available, the task force cannot recommend for or against FIT testing. If FIT test characteristics (ie, specificity and sensitivity) are similar to the general population, these tests could be useful for the CF population. Sigmoidoscopy alone examines only the descending colon and is unsuitable in the CF population because of the increased frequency of polyps and cancers beyond the reach of this instrument.[3,36] Similarly, computed tomography colonography cannot be recommended.

5. The Cystic Fibrosis Foundation recommends that colorectal cancer screening begin at age 40 years in individuals with cystic fibrosis with continued re-screening every 5 years. Colonoscopic screening starting at age 40 years has demonstrated high frequency of adenomatous polyps, including advanced adenomas.[19] Although starting screening at age 30 years may uncover polyps and even some tumors, screening has to balance the risk of screening with the benefits of early detection. With respect to the screening interval, approximately half of the patients with negative index screening colonoscopies developed adenomatous polyps including advanced adenomas, within 5 years.[19] Given the high recurrence rate of adenomas and advanced adenomas, an interval of 5 years for re-screening, compared to 10 years in the general population, is recommended for individuals with CF. The recommendation to initiate screening with colonoscopy at age 40 years is consistent with and supported by the modeling estimates.

6. The Cystic Fibrosis Foundation recommends that individuals with cystic fibrosis who have undergone a colonoscopy that had any adenomatous polyps have surveillance colonoscopy in 3 years, unless a shorter interval is indicated by individual findings, with subsequent intervals based on the most recent endoscopic examination. The shorter intervals (3 years) for most surveillance examinations recommended for individuals with CF vs 5 years in the general population are similar to recommendations for patients with other genetic colon cancer syndromes.[35] However, the CF Foundation recommendation for a 3-year interval for surveillance of patients with multiple or advanced polyps does not differ from the general population with the same findings.[37] The recommendation takes into consideration the burden of a more intensive bowel preparation regimen that is necessary for colonoscopic examinations in CF patients and additional commonly present comorbidities. The endoscopist should also consider quality of the colon preparation and level of confidence that all polyp tissue has been resected in providing individualized recommendations for surveillance interval and utilize a shorter interval when appropriate.

7. The Cystic Fibrosis Foundation recommends that individuals with cystic fibrosis who are 30 years of age and older and have adequately recovered after receiving a solid organ transplant begin colorectal cancer screening within 2 years of transplantation except when they have had a negative colonoscopy within the past 5 years. Although the absolute risk of CRC in individuals with CF is extremely low for patients younger than 30 years, the risk of CRC in individuals with CF greatly increases after lung transplantation, with the risk being 25−30 times the age-adjusted baseline.[2–4,19,36] Median survival of transplant patients, especially those patients that survive the first postoperative year, has now increased beyond 10 years.[38] Increased post-transplantation survival means that many transplant patients will enter older age groups where there is an increased risk of cancer. Screening should be performed after recovery from the operation and within 2 years after the procedure, unless they have had a negative colonoscopy within the previous 5 years.

8. The Cystic Fibrosis Foundation recommends continued colorectal cancer rescreening every 5 years in individuals with cystic fibrosis who have received a solid organ transplant. There is a paucity of data on the re-screening of individuals with CF after lung transplant and an initial screen that discovers no adenomas or CRC, except for one single center study.[19] Based on generally more-intensive screening recommendations for other high-risk populations,[34] the task force voted to recommend rescreening every 5 years (see Figure 2).

Figure 2.

Clinical decision support tool for CRC screening with colonoscopy in adults with CF. *Negative = no adenomatous polyps on examination with good to excellent bowel preparation (score ≥6 on the Boston Bowel Preparation Scale). Testing should be repeated if the bowel preparation is not considered good. ‡Screen = screening colonoscopy.

9. The Cystic Fibrosis Foundation recommends that individuals with cystic fibrosis who have undergone a solid organ transplant and had colonoscopy that had any adenomatous polyps have surveillance colonoscopy in 3 years, unless a shorter interval is indicated by individual findings, with subsequent intervals based on the most recent endoscopic examination. Limited data[9,19] suggest that there is an increased risk of recurrent high-grade polyps in individuals with CF, therefore surveillance should be performed every 3 years. However, in cases with extremely high-risk findings, such as very large polyps or multiple polyps, the standard surveillance interval of 3 years may have to be shortened, potentially requiring retesting within 1 year.[39]

10. The Cystic Fibrosis Foundation recommends that adults with cystic fibrosis undergoing a colonoscopy receive intensive regimens for bowel preparation to allow for optimal examination. The intensive regimen should include: three to four washes (minimum of 1-liter purgative per wash) with the last wash occurring within 4−6 hours before the examination. An adequate bowel preparation is necessary for a quality colonoscopy and optimal detection of colon polyps;[40,41] however, bowel preparation is difficult in CF patients. Groups that reported systematic results of colonoscopies in CF patients used intensive CF-specific bowel preparation regimens.[9,18,19] The main elements to a better preparation include split prep regimens, that is, several smaller volume washes are superior to a single larger-volume wash; performance of the examination soon after the last wash; and (3) patient education to emphasize the importance of bowel preparation for the examination and different elements involved. A sample CF-specific preparation from the Minnesota Cystic Fibrosis Center is included in Supplementary Material.