Patients with concomitant inflammatory bowel disease and primary sclerosing cholangitis often develop colon cancer soon after they are found to have the two coexisting diseases, reported Dr. Erin Withers Thackeray and colleagues in the January issue of Clinical Gastroenterology and Hepatology.
The finding supports the current guideline of annual colonoscopies in these patients, and reinforces the need for counseling and education in this population, she added. The yearly colonoscopies should begin when PSC is diagnosed in an IBD patient, or when IBD is diagnosed in a PSC patient, the authors said (Clin. Gastroenterol. Hepatol. 2011 January [doi:10.1016/j.cgh.2010.09.020]).
Dr. Thackeray of the division of gastroenterology and hepatology at the Mayo Clinic in Rochester, Minn., performed a retrospective chart review of all adult patients with both IBD and PSC who had available pathology reports from colonoscopy or surgery, and who had a biopsy showing colon cancer or dysplasia.
Patients who had undergone colon resection or had a history of previous colorectal cancer or dysplasia were excluded from the study; patients with liver transplant were not excluded.
A total of 54 patients met the study criteria of having both IBD and PSC, plus colonic neoplasia. The study included 16 women and 38 men, with a mean age of 44 years for diagnosis of both diseases.
Overall, 38 of the patients had a diagnosis of IBD that preceded PSC diagnosis by a median of 11 years (with IBD defined as Crohn’s disease, chronic ulcerative colitis, or indeterminate colitis). IBD and PSC were diagnosed simultaneously in seven patients, and nine patients developed IBD a median of 4 years following PSC diagnosis. For the current study, analysis began once both diagnoses were confirmed.
Patients were followed for a mean of 4.2 years, during which time each patient had a median of three colonoscopies (range, two to four). The breakdown of biopsy findings included 14 patients with colorectal carcinoma, 7 with high-grade dysplasia, 3 with dysplasia-associated lesions or masses, and 30 patients with low-grade dysplasia. The dysplasia grade was determined according to the Inflammatory Bowel Disease/Dysplasia Morphology Study Group (Hum. Pathol. 1983;14:931-68).
According to the authors, in the 2-year period following diagnosis of PSC and IBD, there were 21.5 occurrences of either colon cancer or dysplasia per 100 person-years, including 7.6 occurrences of cancer. That was similar to the rate of cancer or dysplasia that occurred 8-10 years after dual diagnosis (20.4 cases per 100 person-years of follow-up, including 6.8 occurrences of cancer).
The authors also sought to characterize the type and location of these early cancers in the patients with IBD and PSC. They found that all 14 cancers were adenocarcinomas, 2 of which were located in the cecum; 5 were in the ascending colon, 4 were in the transverse colon, and 3 were in the rectosigmoid colon.
Regarding the stage of the cancers, the authors noted that "according to the [American Joint Committee on Cancer] staging system for colon cancer, 2 patients had stage I cancer, 4 had stage IIA cancer, 4 had stage IIIB cancer, 2 had stage IIIC, and 2 had stage IV cancer." Four patients died of their malignancy.
In addition to confirming the early occurrence of dysplasia in this population, the study offers what the authors call the first evidence to support the current recommendation for annual colonoscopies in patients with PSC and IBD.
It also characterizes the "widespread" nature of neoplasms that do develop, the authors said, "demonstrating that colonoscopy rather than sigmoidoscopy is important for surveillance purposes in this population."
However, there were limitations, including the fact that the study depended on the accuracy of the medical record, and that the Mayo Clinic is a referral center, "which may influence our patient population and limits follow-up in some cases."
Nevertheless, "future directions for research in this population include determining specific clinical characteristics that can identify patients who are at higher risk for developing colon cancer," wrote the authors.
The authors stated that they had no disclosures relevant to this study.