Screening for Colorectal Cancer: The Accuracy of Fecal Occult Blood

Abstract

In Reply. —Dr Greegor speculates that our colorectal cancers were young and, accordingly, that detection rates were very good. Many primary cancers in the postresection group may have been synchronous rather than metachronous, as they were discovered at the first colorectal follow-up evaluation and were large in size. Nevertheless, premalignant adenomas or early-stage cancers, rather than late-stage cancers, are the important targets for screening. The observed miss rates of about 70% for cancer and 90% for polyps will certainly compromise the efficacy of screening or case detection. We are unaware of data on how a high-roughage diet affects FOBT validity. As we stated in the Methods section, HemoQuant results were expressed as hemoglobin equivalents for the very reasons given by Drs Young and St. John. The various classes of FOBTs detect different components or analytes of hemoglobin, and none measures the molecule in total. Because its analytes include both intact