[Sensitivity of immunochemical occult blood testing in detecting early colorectal cancer]

Sensitivity of immunochemical occult blood testing (IFOBT) for early colorectal cancer (CRC) calculated in known cases is reported to be around 50-60%. Sensitivities of IFOBT for cancer in the preclinical stage were reported based on findings of colonoscopy performed on all screenees. Of 5715 asymptomatic persons who underwent flexible sigmoidoscopy (FS), 13 cases of early cancer were found, within the reach of FS. Sensitivities were 53.8%, 76.9 and 84.6% for one-day test, two-day test and three-day test of IFOBT by immunochemical hemagglutination, respectively. While corresponding figure was only 15.4% for three-day Hemoccult test. Other reports indicated that sensitivity of IFOBT is around 30% for small lesions of early CRC less than 1 cm in diameter. IFOBT is much more sensitive in detecting early CRC than Hemoccult test but is poorly sensitive for tiny early CRC.