The past year has witnessed substantial gains in our knowledge regarding colorectal cancer screening tests. In this issue of The Journal, Ahlquist et al1 provide the best estimate yet of the sensitivity of currently available fecal occult blood tests (FOBTs) for asymptomatic cancer. Confirming what has been suspected previously,2-4 their data indicate that both Hemoccult and HemoQuant methods detect less than 50% of these cancers. Even if we adjust this estimate upward to account for some loss of sensitivity during mailing, estimated sensitivity would not approach 50%.
The authors describe clearly the errors inherent in the many, usually higher, estimates of sensitivity that have been offered over the years. Simply put, the sensitivity of FOBT for asymptomatic cancer cannot be accurately estimated from studies in persons with symptomatic cancers. Both FOBT and full colonoscopy must be performed in several thousand asymptomatic persons to identify those with cancer in