A randomised controlled trial of adults in Norway found that a single screening sigmoidoscopy led to a sustained reduction in colorectal cancer (CRC) incidence for more than two decades after screening, with women seeing a more modest risk reduction than men.

Sigmoidoscopy screening also reduced the risk of death from CRC in only men.

While previous studies have shown sigmoidoscopy screening reduces CRC incidence and mortality for 15 years, these findings suggest that a single flexible sigmoidoscopy can have an even longer-lasting effect on CRC incidence and death, potentially reducing the need for repeated examinations within the usual screening age range.

The study is published in Annals of Internal Medicine.

Researchers from the Cancer Registry of Norway, University of Oslo, and colleagues conducted the NORCCAP (Norwegian Colorectal Cancer Prevention) trial to examine whether the benefits of sigmoidoscopy screening for CRC last beyond 15 years.

They followed over 98,000 adults aged 50 to 64 in Norway who were randomly assigned to either once-only sigmoidoscopy screening, with or without a stool test, or no screening.

After 23 years, sigmoidoscopy screening was associated with a 28% reduction in CRC incidence and a 37% reduction in CRC death in men.

In women, sigmoidoscopy screening was associated with an 11% reduction in CRC incidence and no corresponding reduction in CRC death. The authors conclude that a single sigmoidoscopy screening provides a sustained benefit in CRC incidence reduction, particularly in men.

Source: American College of Physicians