Abstract
We examined the usefulness of two methods as screening tests for colorectal cancer, and compared their usefulness to that of the fecal occult blood test (FOBT). The first method was the detection of the K-ras gene mutation in feces as a related genetic marker. The second method was the measurement of fecal lactoferrin (Lf) as a related inflammatory marker. The K-ras gene mutation was not detected in normal control subjects (0/20), and it was detected in only 13 out of 31 cancers. Therefore, it was determined that the sensitivity of this detection is less than that of the FOBT. Also, this method implies complicated procedures which require more than 2 days to complete, so it cannot be utilized as a screening test, like the FOBT. Measurement of Lf had a higher sensitivity (61.1%) than the FOBT (50.0%) for colorectal cancers, and its sensitivity was 3times higher than that of the FOBT in early-stage colorectal cancer (35.8%/11.8%). For mass screenings at the work place, the positive rate of Lf was 2.5%, lower than that of the FOBT (3.3%). This suggests that measurement of Lf can decrease the check-up rate and increase detection of cancers. The positive rate of Lf measurement and the FOBT combined was 0.4% in mass screenings at the work place. Lf can be measured by an automatic analyzer, so this method would easily increase the efficiency of mass screenings for colorectal cancer, whether it is used alone or in combination with the FOBT.
