Adults with cystic fibrosis (CF) should undergo screening colonoscopy for colorectal cancer every 5 years beginning at age 40 years, unless they have had a solid organ transplant – in which case, screening should begin at age 30 years. For both groups, screening intervals should be shortened to 3 years if any adenomatous polyps are recovered.
The new screening recommendation is 1 of 10 set forth by the, in conjunction with the American Gastroenterological Association. The document reflects the significantly increased risk of colorectal cancer among adults with the chronic lung disorder, and his colleagues wrote in the February issue of . ; the risk approaches a 30-fold increase among CF patients who have undergone a lung transplant.
SOURCE: American Gastroenterological Association
In addition to making recommendations on screening intervals and protocols, the document asks clinicians to reframe their thinking of CF as a respiratory-only disease.
“Physicians should recognize that CF is a colon cancer syndrome,” wrote Dr. Hadjiliadis, director of the Adult Cystic Fibrosis Program at the University of Pennsylvania, Philadelphia, and his coauthors.
The increased colorectal cancer risk has become increasingly evident as CF patients live longer, Dr. Hadjiliadis and the panel wrote.
“The current median predicted survival is 41 years, and persons born in 2015 have an estimated average life expectancy of 45 years. The increasing longevity of adults with CF puts them at risk for other diseases, such as gastrointestinal cancer.”
In addition to the normal age-related risk, however, CF patients seem to have an elevated risk profile unique to the disease. The underlying causes have not been fully elucidated but may have to do with mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), which are responsible for the excess thickened mucosal secretions that characterize CF. CFTR also is a tumor-suppressor gene in the intestinal tract of mice, and is important in gastrointestinal epithelial homeostasis. “Absence of CFTR is associated with dysregulation of the immune response, intestinal stem cells, and growth signaling regulators,” the authors noted.
In response to this observed increased risk of colorectal cancers among CF patients, the Cystic Fibrosis Foundation convened an 18-member task force to review the extant literature and compile colorectal cancer screening recommendations for CF patients who show no signs of such malignancies. The team reviewed 1,159 articles and based its findings on the 50 most relevant. The papers comprised observational studies, case-control studies, and case reports; there are no randomized clinical trials of screening for this population.
The American Gastroenterological Association reviewed and approved all of the recommendations:
- Screening decisions should be a collaborative process between the CF patient and clinician, taking into account comorbidities, safety, and quality of life. This should include a discussion of expected lifespan; patients with limited lifespan won’t benefit from screening for a slow-growing cancer. Patients should also consider that the colonoscopy prep for CF patients is somewhat more complex than for non-CF patients. “Given these complexities, the task force agreed that individuals with CF and their providers should … carefully assess the risks and benefits of CRC screening and its impact on the health and quality of life for the adult with CF.”
- The decision team should include an endoscopist. An endoscopist with CF training is preferred, but the panel noted these specialists are rare.
- Colonoscopy is the preferred method of screening for CF patients, since it can both detect and remove polyps. “This is one of the main reasons why colonoscopy is the screening procedure of choice for other high-risk groups,” the panel noted.
- There is insufficient evidence to recommend alternate screening methods in CF patients, including CT scanning, colonography, stool-based tests, or flexible sigmoidoscopy.
- In CF patients without signs of CRC, screening should commence at age 40 years and be repeated every 5 years as long as the results are negative.
- Any CF patient who has had adenomatous polyps on a screening colonoscopy should have a repeat colonoscopy within 3 years, unless clinical findings support more frequent screening.
- For any adult CF patient older than age 30 years who has undergone a solid organ transplant, screening colonoscopy should commence within 2 years of transplantation. “Although the absolute risk of CRC in individuals with CF is extremely low for patients younger than 30 years, the risk … greatly increases after lung transplantation,” to 25-30 times the age-adjusted baseline, the panel wrote. “Increased posttransplantation 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 and within 2 years, unless there was a negative colonoscopy in the 5 years before transplant.
- Thereafter, patients who have had a solid organ transplant should undergo colonoscopy every 5 years, based on their life expectancy. “In cases where the expected survival time is limited (less than 10 years), screening should not be performed. For adults appropriately selected, lung transplantation usually increases survival probability. Therefore, a lung transplantation candidate with a short life expectancy is likely to become a screening candidate before and after transplantation at the appropriate ages described here, because the potential survival increases to approximately 10 years.”
- Colonoscopy should be repeated every 3 years on CF patients with transplants with a history of adenomatous polyps. This interval may be as short as 1 year for patients with high-risk, large, or multiple polyps.
- CF patients should undergo more intense bowel prep for colonoscopy, with three-four washes of a minimum of one liter of purgative per wash; the last wash should occur 4-6 hours before the procedure. Split-prep regimens (several smaller-volume washes) are better than a single larger-volume wash. The panel suggested a sample CF-specific regimen available from the Minnesota Cystic Fibrosis Center.