麻豆传媒

LAS VEGAS -- Treatment advancements appear to have helped cut colectomy rates to treat colorectal cancer among patients with ulcerative colitis (UC), according to a presentation here.

With emerging advances in treatment and surveillance, colectomy rates in Canada's Alberta province declined 8.6% annually from 2003 to 2015 for colorectal cancer, reported Sherman Picardo, MBBS, of University of Calgary in Alberta, at the .

From about 2.8 per 1,000 UC patients at risk in 2003, colectomy rates in Alberta dipped to 0.5 per 1,000 in 2015, Picardo said. The analysis was based on provincial registry data, allowing researchers to identify UC patients who had colorectal cancer diagnoses and colectomies, as well as their histories of colonoscopy.

UC patients face increased risk of colorectal cancer. Severity of histologic bowel inflammation, gender, age, duration and degree of disease activity, simultaneous primary sclerosing cholangitis, and a family history of sporadic colorectal cancer are independent risk factors of colorectal cancer, Picardo noted.

There are a number of international guidelines on the technique and frequency of surveillance. (AGA) in 2010 recommended a screening colonoscopy in all patients with colitis up to 8 years following diagnosis. Clinicians are advised to biopsy each segment to quantify the extent of the microscopic disease activity. A follow-up colonoscopy is recommended 1 to 2 years after the initial procedure and after two negative examinations. These follow-up colonoscopies can be spread out every 1 to 3 years, or more often depending on the patient's risk factors, Picardo noted here.

The AGA guidelines also suggested chromoendoscopy if the operator is trained in the technique. When chromoendoscopy is performed, target biopsies are advised. However, if white light endoscopy is done, each segment should be biopsied and a minimum of 33 biopsies should be taken, Picardo continued.

The overall "decline is likely attributable to development and utilization of surveillance programs and improvements in treatment options for patients," Picardo told congress attendees.

Picardo and his colleagues identified 112 colorectal cancer cases among UC patients, of whom 86 had colonoscopy in the year preceding colectomy and 26 did not. Of those that did have a recent colonoscopy, 33 had not had another in the previous 5 years. Of the 26 without a recent colonoscopy, none had one in the previous five years. Both findings suggested that the guideline recommendations for follow-up colonoscopy in UC patients were not uniformly followed.

The researchers' analysis of yearly rates assumed a Poisson distribution, using admission year as the primary predictor, with adjustment for gender and age, and using a generalized linear model.

One of the researchers' goals in the study, Picardo said, was to identify significant "inflection points" in the time course of colectomy rates. Although the overall decline was not entirely linear -- there were spikes in 2009 and 2013-2014 -- these did not qualify as inflection points, Picardo said.

He cited some limitations of the investigation. "We are using administrative data so that makes it prone to data entry error and because the databases are deidentified we are unable to validate individual diagnostic codes. We were also unable to look at risk factors such as disease extent and duration as well as other potential risk factors of obesity such as smoking," Picardo said.

"We did not have access to information about medications such as biologic therapy in women, which influence cancer rates. We were also unable to link to cancer databases to identify that site of the cancer, but we are hopeful we will be able to do this in the near future. We also lacked information about dysplasia detection," he continued.

"Future prospective studies are needed to evaluate the efficacy of surveillance programs in detection of dysplasia and survival outcomes," Picardo concluded.

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