Detecting colorectal cancer with a large scale fecal occult blood testing program.

The researchers analyzed outcome data for 439 persons who had positive fecal occult blood tests in a 1984 statewide program for Connecticut residents. Among those with positive test results, colorectal cancer was diagnosed in 33 persons, 7.5 percent of the sample, during 3.5 years of follow-up. More than one-half of all cases found, 15 of 29 persons, or 52 percent, were diagnosed with in-situ or localized tumors, which are most likely to be treated successfully. The predictive value of a positive test varied according to the screened person's age and the number of positive tests obtained from that person. Among those 60 years or older, the positive predictive value of the screening test was 9 percent, compared to 3 percent for persons younger than 60 years. Having more than one positive test was associated with a positive predictive value of 12 percent, compared to 5 percent for one positive test. The findings support the use of fecal occult blood testing for early detection of colorectal cancer.