Advantage of immunochemical fecal occult blood test in screening for colorectal cancer

Colorectal cancer screening is a high public health priority in all industrialized countries. However: the loan sensitivity of the common guaiac screening test (Haemoccult II (R)) snakes practitioners and public health decider, reluctant to set up national screening program. In recent years, immunochemical tests based on the use of a specific antibody have been found to be more sensitive than the Haemoccult II (R) test. However; for screening purposes, any gain in sensitivity is of interest only if specificity and positive predictive value are satisfactory. As instance, rehydration of the Haemoccult II (R) test prior to lecture can increase sensitivity, but the associated decrease in specificity and positivity predictive value and the high positivity rate render its value in mass screening debatable. Moreover, extra costs, if existing, must be acceptable for the society. Until recently, immunochemical tests costs made it unaffordable in our societies. The arrival of automated reading is likely to remove this obstacle. Moreover it offers the opportunity of positivity cut-off choice. A recent study was conducted in Cotentin (France) to assess the performance. of an immunochemical test with an automated reading technique (Magstream 1000) for different haemoglobin content cut-off points, As previous American, Japenese, Chines and Italian studies. this study suggests that the use of immunochemical tests could lead a substantial gain, in screening sensitivity. Moreover by choosing a higher haemoglobin content as cut-off point (50 ng/ml instead of usual cut-off at 20 ng/ml), a gain in sensitivity cart be obtained with a satisfactory specificity (97 %) and positivity rate (3 %()). Considering the increasing number of publications; the use of an immunochemical test with an automated reading technique could improve the prospects for mass-screening for colorectal cancer, since it offers a promising alternative to guaiac tests.