Risk for pouch cancer not elevated after ileal pouch-anal anastomosis for UC

Last Updated: 2017-08-28

By Will Boggs MD

NEW YORK (Reuters Health) - Patients who undergo ileal pouch-anal anastomosis (IPAA) after colorectal excision for ulcerative colitis (UC) do not have an increased risk of pouch or extraintestinal cancers, researchers from Denmark report.

"It was an interesting and reassuring finding that the overall (total) risk of cancer following IPAA for UC was comparable to that of the background population," Dr. Anders Mark-Christensen from Aarhus University Hospital, in Denmark, told Reuters Health by email. "The most interesting - although not completely surprising - finding was the very low risk of pouch cancer."

Residual mucosa left at the anal transition zone and rectal cuff could present a persistent risk of cancer after IPAA, and the risk of extraintestinal cancers in UC patients appears to be slightly higher than in the general population. The cancer risk following colectomy and IPAA remains uncertain.

Dr. Mark-Christensen and colleagues investigated the risk of cancer, focusing on pouch cancer, in 1,723 patients with IPAA who were matched to 8,615 individuals from the background population. The study was published online, August 3, in the Journal of Crohn's and Colitis.

During a median follow-up of 12.9 years, only 2 patients (0.12%) with IPAA were diagnosed with pouch cancer, an incidence of 8.4 cases per 100,000 person-years. By comparison, 3 small-bowel cancers occurred in the background population, an incidence of 2.6 cases per 100,000 person-years. The overall incidence of any cancer did not differ significantly between the IPAA group and the background population.

IPAA patients had a higher risk of hepatobiliary cancer, but the finding lost significance after excluding patients who had primary sclerosing cholangitis at the time of cancer diagnosis. The IPAA patients also had a non-significantly higher risk of non-melanoma skin cancer.

Smoking-related cancers were 30% less common among IPAA patients than in the background population, but this estimate was based on few cases.

"A growing body of evidence suggests that the risk of developing cancer of the pouch is extremely low," Dr. Mark-Christensen said. "In general terms, there are several arguments against screening for these cancers in general IPAA populations: First, the natural history of pouch cancer is virtually unknown, so it is unclear if there is a therapeutic window of opportunity before the cancer becomes symptomatic, where treatment will improve prognosis. This assumption has to be fulfilled before screening can even be considered. Second, a notable number (of the overall extremely low number) of pouch cancers are not visible on endoscopy, so this is by no means a perfect screening tool!"

"As we mention in the paper, selective - rather than general - pouch cancer screening of IPAA subgroups (e.g., those with primary sclerosing cholangitis, prior colorectal cancer, family history of colorectal cancer, etc.) may be reasonable, but we do not know if such an approach benefits patients either," he concluded.

SOURCE: http://bit.ly/2vsXkie

J Crohns Colitis 2017.