A Norwegian study of screening with one-time flexible sigmoidoscopy demonstrated a drop in the colorectal cancer incidence rate by 20 percent and the death rate by 27 percent.

The study, published in the August 13 issue of JAMA, found that randomized screening with flexible sigmoidoscopy and fecal occult blood testing (FOBT) lowered the risk of cancer each year in the screened group after the first year, wrote author Øyvind Holme, MD, and colleagues, of the Sorlandet Hospital Kristiansand in Kristiansan, Norway.

A total of 98,792 participants included 78,220 in the control group and 20,572 in the screening group. The screening group was divided into two subgroups: one comprised of 10,283 who received a flexible sigmoidoscopy, and another made up of 10,289 participants who got a flexible sigmoidoscopy and FOBT. The median follow-up time was 11.2 years in the screening group and 10.9 years in the control group.

The authors reported that 253 participants in the screened group were diagnosed with colorectal cancer versus 1,086 in the control group, (112.6 vs. 141.0 cases per 100,000 person-years) an absolute rate difference of 28.4 percent.

“Our results are in accordance with those reported from the previous trials and extend them,” the authors wrote.

After a median of about 11 years, 71 participants died of colorectal cancer in the screened groups vs. 330 in the control group, an absolute rate difference of 11.7 percent per 100,000 person years.

Adding FOBT did not make a difference in outcomes, according to Holme and colleagues.

The screening was conducted in 1999-2000 (55 – 64 year age group) and in 2001 (50-54 year age group), with a follow-up in December 2011. Only screened participants who were diagnosed with cancer were offered a colonoscopy. Adherence to screening was 63 percent.

Younger participants aged 50 to 54 years seemed to benefit at least as much from the screening intervention as older participants aged 55 to 64 years, wrote the authors.

In an associated editorial on the study, Allan S. Brett, MD, of the University of South Carolina School of Medicine, wrote that the study highlights an irony for U.S. clinicians. “By far, colonoscopy has become the most commonly recommended and performed endoscopic colorectal cancer screening tool in the United States, whereas screening by sigmoidoscopy has all but vanished.”

Brett also noted that the debate between sigmoidoscopy, colonoscopy or CT colonography may soon be rendered moot by another screening technique, stool DNA testing, which has shown 92 percent sensitivity for detecting cancer and 42 percent sensitivity for detecting advanced precancerous lesions.

“Repeated at some defined interval, stool DNA testing has potential to reduce colorectal cancer mortality substantially while sharply reducing the number of routine colonoscopies,” wrote Brett. “For now, however, the muddled landscape of colorectal cancer screening in the United States continues, and the place of flexible sigmoidoscopy among screening tools remains unsettled.”