Accuracy of Fecal Occult Blood Screening for Colorectal Neoplasia: A Prospective Study Using Hemoccult and HemoQuant Tests

Objectives. —To define the validity of fecal blood as a marker for colorectal neoplasia in the screening setting and to compare yields by Hemoccult and HemoQuant fecal occult blood screening tests. Design. —A multicenter masked comparison of fecal blood test results against structural colorectal evaluations and longitudinal follow-up, serving as criterion standards, in nonreferred subjects at risk for colorectal neoplasia. Setting. —Communities, primary care centers, referral centers. Participants. —Two groups: (1) 1217 patients aged at least 18 years undergoing routine structural surveillance evaluations following curative resection of a colorectal tumor and (2) 12312 relatives of colorectal cancer patients aged at least 50 years. Interventions. —Blinded Hemoccult II and HemoQuant testing on three mailedin stool samples per subject. Main Outcome Measure. —Sensitivity of fecal blood tests for colorectal neoplasia. Results. —In the postresection group, surveillance evaluations revealed 46 malignant colorectal neoplasms and 402 polyps. At matched specificity, sensitivity of either test for cancer was 26% (95% confidence interval, 13% to 39%). Hemoccult was positive in 21% of intraluminal recurrences, 33% of all new primary tumors, and 29% of Dukes A or B cancers; HemoQuant was elevated in 24%, 28%, and 29%, respectively. Sensitivity for polyps 1.0 cm or larger was 13% by Hemoccult and 11% by HemoQuant. In the group of relatives, estimated sensitivity for cancer at 1 to 3 years of follow-up was 25% to 33% by Hemoccult, not significantly different from the 29% to 43% by HemoQuant. Conclusions. —Based on our observations in the screening setting, fecal blood appears to be a poor marker for colorectal neoplasia. Most cancers and the vast majority of polyps will be missed. Hemoccult and HemoQuant are similarly insensitive.