[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 low sensitivity of the common guaiac screening test (Haemoccult II) makes practitioners and public health deciders 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 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 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, Japanese, Chinese 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 can 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.
Launoy
Guy
G
Cancers & Populations, ERI3 Inserm, EA 3936 Université Caen, UFR Médecine, Centre hospitalo-universitaire, avenue de la Côte-de-Nacre, 14032 Caen Cedex. guy.launoy@unicaen.fr
Berchi
C
C
D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005602:France; D006138:Guaiac; D006441:Hemoglobin A / Q000032:analysis; D006801:Humans; D007159:Immunologic Tests; D007202:Indicators and Reagents; D009780:Occult Blood; D011446:Prospective Studies; D012680:Sensitivity and Specificity
D007202:Indicators and Reagents; D006138:Guaiac; D006441:Hemoglobin A