Fecal Blood Test Defines Risk of Colorectal Cancer

Immunochemical fecal occult blood testing (iFOBT), uses antibodies to detect hidden human hemoglobin in stool, and is widely used to screen for colorectal cancer.

Individuals with fecal hemoglobin concentrations higher than 100 ng/mL are at increased risk of colorectal neoplasia, but little is known about the subsequent risk of developing colorectal neoplasia for people who have a negative result.

A team from the National Taiwan University (Taipei, Taiwan) examined 44,324 participants from a community-based iFOBT screening program for residents aged 40-69 years, between 2001 and 2007. The participants who had negative results at the first screen were followed up to find cases of colorectal neoplasia. Modeling was used to calculate the risk of developing neoplasia after controlling for conventional risk factors including age, sex, family history of colorectal cancer, consumption of meat, and body mass index. They also calculated the subsequent risk for nonreferrals, individuals with fecal hemoglobin concentrations higher than 100 ng/mL who refused colonoscopy, and false positives, in whom colonoscopy did not find disease.

Among individuals with negative results, hemoglobin concentration was predictive of neoplasia and subsequent progression to cancer. The median follow-up was 4.39 years for all participants, during which the incidence of colorectal neoplasia increased from 1.74/1,000 person-years for those with baseline fecal hemoglobin concentration 1 ng/mL - 19 ng/mL, to 7.08/1,000 person-years for those with a baseline concentration of 80 ng/mL - 99 ng/mL. The higher the initial fecal hemoglobin concentration was, the greater the likelihood there was of developing colorectal neoplasia. Nonreferrals had the highest risk of colorectal neoplasia and false-positive cases the lowest risk.

The fecal hemoglobin was measured using the OC-Sensor iFOBT kits manufactured by Eiken Chemical Co. (Tokyo, Japan). The authors suggest that fecal hemoglobin could be used to define groups at low, intermediate, and high risk and tailor screening strategies accordingly. Callum G. Fraser, PhD, a professor at the University of Dundee, (UK), commenting on the study said, "There is likely a continuum of risk of colorectal neoplasia as fecal hemoglobin increases from zero. These findings have important implications for the design of future screening programs." The study was published on May 16, 2011, in Lancet Oncology.

Related Links:
National Taiwan University
Eiken Chemical Co.