Fecal blood test cuts colon cancer deaths

Fecal blood test cuts colon cancer deaths

16/10/2013

SAN DIEGO -- Annual fecal occult blood screening reduced the mortality associated with colorectal cancer by one-third, with benefits persisting over 30 years, a researcher said here.

In a large study that began in 1975, the relative risk for colorectal cancer mortality was 0.68 (95% CI 0.56-0.82) for individuals screened annually and 0.78 (95% CI 0.65-0.93) for those screened biennially compared with those not screened, which translated into relative risk reductions of 32% and 22%, respectively, Aasma Shaukat, MD, of the Minneapolis VA Medical Center, reported at the annual meeting of the American College of Gastroenterology.

Three randomized clinical trials have evaluated the effects of screening on colorectal cancer mortality, with the longest follow-up to date being 20 years.

The first of those trials, the Minnesota Fecal Occult Blood Trial, recruited 46,551 individuals in Minnesota and Wisconsin ages 50 to 80, randomizing them to annual, biennial, or no screening.

After 18 years of follow-up, the relative risk for colorectal cancer mortality was 0.67 (95% CI 0.51-0.83) for annual screening and 0.79 (95% CI 0.62-0.97) for biennial screening, which represented relative risk reductions of 33% and 21%.

In that study, anyone who had a positive fecal occult blood test result or other suggestive symptoms underwent a colonoscopy with polypectomy if needed.

The other two randomized studies, conducted in England and Denmark, found risk reductions for colorectal cancer mortality of 18% after 13 and 20 years of follow-up, respectively.

The current analysis of the Minnesota trial extended the follow-up for the original cohort to 30 years, during which time 71% of participants died.

Of the 732 deaths from colorectal cancer, 200 were in the group that had been screened annually, 237 were in the group screened biennially, and 295 were in the control group.

On a Kaplan-Meier survival curve, there was fairly clear separation between the control group and the annual screening group, beginning at about 13 years of follow-up and continuing through 30 years, Shaukat said.

Unlike colorectal cancer mortality, no difference for all-cause mortality was seen for screening through 30 years, with relative risks of 1 and 0.99 for annual and biennial screening, respectively.

In subgroup analyses, men seemed to derive greater benefits from screening than women, particularly those ages 60 to 69 whose relative risk for colorectal cancer mortality was 0.62 (95% CI 0.50-0.78).

Throughout the study, adherence to screening was high, at 90%. Positive results were seen for 10% of individuals at each screening, and overall 83% had a colonoscopy at some point.

"The consistent 32% decrease suggests the effect of polypectomy, because many of the detected polyps could have become cancerous during the 30 years of follow-up," she said.

Limitations of the study included cause of death information being obtained from an administrative database rather than through chart review, and underpowering for comparing differences in all-cause mortality.

 

Source: MedPage Today: http://www.medpagetoday.com/MeetingCoverage/ACG/42296

Login to your account

Did you forget your password?