Colorectal Cancer Risk Clarified in High-Risk Group

Tara Haelle

August 19, 2015

Approximately one in six patients with serrated polyposis syndrome will go on to develop colorectal cancer, according to a study published online August 11 in Gut.

This incidence is lower than previously suspected, and the researchers identified factors associated with elevated risk.

Moreover, surveillance with colonoscopy effectively drops the risk to 1.9% in 5 years, Sabela Carballal, MD, from the University of Barcelona in Spain, and colleagues report. They note, however, that annual surveillance may not necessarily be required.

"Our results also demonstrate that [colorectal cancer] risk is independently associated with specific phenotypic characteristics of serrated polyps," the researchers write. "Indeed, the number of proximal [sessile serrated adenomas/polyps] and the presence of high-grade dysplasia in proximal [sessile serrated adenomas/polyps] are able to identify patients at high risk of developing colorectal cancer."

The researchers retrospectively enrolled 296 patients with serrated polyposis syndrome from 18 Spanish centers between March 2013 and September 2014. All patients met World Health Organization criteria 1 and/or 3 for serrated polyposis syndrome, diagnosed at a mean age of 57.2 years, and 78% had been diagnosed during screening colonoscopies. Nearly a third of patients (29.4%) had a first-degree family history of colorectal cancer.

The researchers identified colorectal cancer risk factors based on medical, endoscopy, and histopathology report data dating back as early as 1993, although 82.8% of the patients received their diagnoses in 2010 or later. They then tracked the patients, with a median 26 serrated polyps and three adenomas, for a median 45 months. In total, the patients had 1008 colonoscopies, 31.6% of which were for surveillance, with median intervals of 16 months. Among 11,270 polyps identified, 87.2% were serrated and 12.8% were adenomas.

During follow-up, 47 patients (15.8%) developed colorectal cancer at a mean age of 53.9 years; four of these cases (8.5%) were detected during surveillance. An average 12 months passed between the last surveillance colonoscopy and detection of colorectal cancer (without clinical symptoms) in these four patients, none of whom had clinical symptoms.

Among, patients diagnosed with colorectal cancer, 46.8% of tumors were in the proximal colon, and 53.2% were in the distal colon. Among patients with no prior history of colorectal cancer, cumulative risk during a follow-up of 4.9 years was 1.9%.

The researchers were able to identify three risk groups among the patients, based on the presence or absence of two features: more than two sessile serrated adenomas/polyps proximal to splenic flexure and at least one proximal serrated adenoma/polyp with high-grade dysplasia. The presence of one feature increased risk by nearly twofold compared with none (odds ratio [OR], 1.98; 95% confidence interval [CI], 1.02 - 3.81; P = .04), and the presence of both features was associated with a 4-fold increase (OR, 4.27; 95% CI, 1.30 - 14.03; P = .01). Presence of the former occurred in 55.3% of catients with cancer and 36.9% of patients without cancer. The latter occurred in 12.7% of patients with cancer pnd in 4.8% of patients without cancer.

The researchers did not identify any demographic characteristics or other clinical features associated with colorectal cancer development.

"Overall, our results indicate that intensive surveillance should be tailored according to the presence of risk factors in order to offer the optimal treatment and surveillance protocol for patients with [serrated polyposis syndrome]," the authors write.

"[F]urther prospective studies are needed to clarify the relationship between histopathology factors identified in this study and [colorectal cancer] development."

The research was funded by the Instituto de Salud Carlos III, the European Regional Development Fund, A Way of Making Europe, Gonzalo Miño scholarship of the Spanish Association of Gastroenterology, Ministry of Economy and Competitiveness, Scientific Foundation of the Spanish Association Against Cancer, Agency for Administration of University and Research, and Tumor Bank Network of Catalonia. The authors have disclosed no relevant financial relationships.

Gut. Published online August 11, 2015. Abstract

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