Abstract
The immunological test for occult blood in feces is recognized as an effective means of detecting colorectal cancers, and has been used for community and workplace mass screenings. However, fewer detailed examinations than recommended are actually performed, which presents a problem, and this tendency is felt particularly with the workplace mass screenings. In order to increase the rate of detailed examinations, we analyzed the results of the immunological tests for occult blood in feces in order to identify any high-risk group for colorectal cancer. We conducted immunological tests for occult blood in feces (twice-sampling method) on 73,955 people who underwent mass screenings for colorectal cancer in our facility in 1999 through 2001. The results showed that 52% of advanced cancer cases and 54% of early cancer (submucosal invasion) cases had a high total value of occult blood in feces: 1500ng/ml or more. This level is significantly different from that of early cancer (mucosal invasion) cases and other benign diseases (p<0.05). In cases with a test value of 1500ng/ml or more, the ratio of positive reactions indicating colorectal cancer was 11.7%. The number of cases of colorectal cancer detected in males was 1.5 times greater than the number detected in females. The rate of detection for people aged 45 or older was increasing with age. However, the rate of detailed screenings only increased for patients aged 60 or older. Consequently, we believe that cases in which the patient is aged 45 or older, and for which the total value as obtained by means of the immunological test for occult blood in feces (twice-sampling method) is 1500ng/ml or higher, should be included in the high-risk group. We are strongly advising these patients to undergo detailed examinations from 2003 onwards.
