In serrated polyposis syndrome, certain factors predict cancer risk

Last Updated: 2015-08-18

By Laura Newman

NEW YORK (Reuters Health) - In patients with serrated polyposis syndrome, the number and location of proximal sessile serrated adenomas/polyps can help predict risk for colorectal cancer, a new report says.

The retrospective study involved 296 patients at 18 specialized centers across Spain, including 47 (15.8%) who presented with colorectal cancer at a mean age of 53.9.

Overall, the authors found a median of 26 serrated polyps and 3 adenomas per patient, with nearly a third of the polyps located proximally, 15.9% in the descending colon, and 52.7% in the rectosigmoid colon.

As reported online August 11 in Gut, pathologic review found cytological dysplasia in 5.4% of the polyps, low-grade dysplasia in 5%, and high-grade dysplasia in 0.4%.

The prevalence of cancer "was similar across the different colonic phenotypes (criterion I vs III vs I+III), and tumors were equally distributed throughout the colon," the authors reported, with 22 (46.8%) in the proximal colon and 25 (53.2%) in the distal colon.

In 35 patients (74.5%), the cancer was found at the initial colonoscopy. Another eight patients were diagnosed with cancer before the diagnosis of serrated polyposis syndrome.

Four tumors (8.5%) were detected during scheduled surveillance colonoscopies. Three of the four were found at an early stage.

"The cumulative risk for patients with no prior history of colorectal cancer (267/296, 90.2%) was 1.9% with a mean follow-up of 4.9 years," the researchers reported.

"After statistical evaluation of the most meaningful cut-offs," the authors came up with two independent predictors of higher cancer risk. The first - more than two sessile serrated polyps proximal to the splenic flexure - was present in 55.3% of patients with cancer vs 36.9% of those without it (OR=2.11, p=0.02). The second - any proximal sessile serrated polyp with high-grade dysplasia - was present in 12.7% of patients with cancer vs 4.8% of those without it (OR=2.90; p=0.03).

Patients with neither risk factor showed a 55% decrease in cancer risk (p=0.01). By comparison, in patients with either of the two risk factors and in those with both risk factors, the authors observed a twofold linear increasing probability of developing a colorectal cancer for each additional risk factor (incremental OR=2; p=0.006).

The authors call for surveillance to be done at specialized centers, but they don't recommend specific follow-up intervals. "Annual surveillance could be excessive," they write. Instead, follow-up "should be tailored according to the presence of colorectal cancer risk factors."

"This is a really informative study," Dr. Charles Kahi, GI Section Chief at the Roudebush Veteran Administration Hospital in Indianapolis, Indiana, told Reuters Health by phone.

"There is no one-size-fits-all for these polyps, and the number and degree of aggressiveness varies," he added.

Dr. Kahi stopped short of saying the study will change surveillance practice, but he did say it would help in selecting lower risk patients who need less frequent surveillance.

Dr. Anne Zauber of Memorial Sloan-Kettering Cancer Center in New York City told Reuters Health by email that while the study is "well-balanced," the retrospective design and the relative short follow-up are limitations.

Also, she noted, "Information on risk factors for colorectal cancer at surveillance colonoscopy is limited given only four CRC cases were detected."

Dr. Sabella Carballal, the study's lead author, from the Department of Gastroenterology, Hospital Clinic in Barcelona, wrote in an email that "serrated polyposis syndrome is still unknown for many gastroenterologists," and she hopes the new data will help guide clinical practice.

Still, she said, "I firmly think that more studies are needed to confirm our findings."

SOURCE: http://bit.ly/1JoLrj4

Gut 2015