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23-05-2012 | Article

Routine flexible sigmoidoscopy screening reduces CRC incidence, mortality


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MedWire News: Routine flexible sigmoidoscopy screening is associated with a significant reduction in overall colorectal cancer (CRC) incidence and mortality, according to results of a large randomized clinical trial.

Flexible sigmoidoscopy was associated with a 21% reduction in CRC incidence among patients randomized to be routinely screened with the technique, compared with participants assigned to usual care, reported Robert Schoen (University of Pittsburgh, Pennsylvania) and co-authors in the New England Journal of Medicine.

The routine sigmoidoscopy approach was also was associated with a 26% reduction in overall cancer mortality compared with usual care, and with a 50% lower incidence of deaths from cancers arising in the distal colon. There was no significant difference in deaths from cancers in the proximal colon, however.

"Endoscopic testing appears to have a more potent protective effect than fecal occult-blood testing in reducing the incidence of colorectal cancer and requires fewer rounds of testing, presumably because endoscopic testing detects more precursor adenomas. However, whether endoscopic evaluation is a better screening test depends on the population and available resources," the authors comment.

The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial enrolled 154,890 participants from 1993 through 2001, aged 55 to 74 years, and randomly assigned them to undergo routine screening with flexible sigmoidoscopy at baseline and again at 3 or 5 years, or usual care, in which they underwent sigmoidoscopy only on request or on the recommendation of a physician. Of the 77,445 assigned to sigmoidoscopy, 83.5% underwent baseline screening, and 54.0% underwent baseline and follow-up screenings.

At least one screening was positive for the presence of a polyp or mass in 26.5% of participants. Of this group, 80.5% had a diagnostic intervention, primarily colonoscopy within 1 year.

After a median 11.9 years of follow-up, there were 1012 cases of CRC in the screening group, yielding an incidence of 11.9 cases per 10,000 person-years. In comparison, there were 1287 cases among the 77,445 participants assigned to usual care, for an incidence of 15.2 cases per 10,000 person-years (relative risk [RR]=0.79).

Flexible sigmoidoscopy was associated with a lower relative risk for distal cancers (RR= 0.71) and proximal CRC (RR=0.86).

The incidence of death from CRC was 2.9 per 10,000 person-years in the sigmoidoscopy group, compared with 3.9 per 10,000 in the usual care group (RR=0.74). Deaths from distal CRC were 50% lower among patients who underwent sigmoidoscopy (RR=0.50), but there was no between-group difference in mortality from proximal CRC (RR=0.97).

By Neil Osterweil