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 Cystic Fibrosis Foundation , in conjunction with the American Gastroenterological Association. The document reflects the significantly increased risk of colorectal cancer among adults with the chronic lung disorder, Denis Hadjiliadis, MD, and his colleagues wrote in the February issue of Gastroenterology . CF patients face up to a 10-fold risk of colorectal cancer, compared with the general population; the risk approaches a 30-fold increase among CF patients who have undergone a lung transplant.
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:
The new document reflects expert consensus on the currently available data, the panel said. As more data emerge, the recommendations might change.
“It is possible that different subpopulations will need more or less frequent schedules for rescreening and surveillance. Our recommendations are making an effort to balance the risk of missing advanced colorectal cancer and minimizing the burden and risk of too frequent examinations.”
None of the panel members had any financial disclosures.
SOURCE: Hadjiliadis D et al. Gastroenterology. 2017 Dec 28. doi. org/10.1053/j.gastro.2017.12.012