Laboratory study on occult gastrointestinal bleedings: differential diagnostic method for the parallel study of intact and fragmented hemoglobin

[The state of the colorectal screening in Hungary: lessons of the pilot programs]

In Hungary, colorectal cancer is the second most common malignant disease. Due to its natural history, colorectal cancer is particularly suitable for screening. At present, epidemiological evidences of the effectiveness of detection of the symptomless colorectal cancer and its precursors are only available for the demonstration of fecal occult blood, endoscopic methods are also in use. For mass screening, fecal occult blood tests are recommended. Guaiac-type chemical methods are widely criticized because of the lack of specificity. Out of the emerging technologies, immunochemical methods based on the antigenicity of blood proteins (hemoglobin) seem to be the most suitable. In the model programmes organized in the frame of the National Public Health Programme, an immunochemical method using two blood proteins (hemoglobin and albumin) have been used. The compliance was not more than 30-45%. About one-third of those with positive blood test refused colonoscopy. The programmes revealed a great number of adenomatous polyps and early cancers, and in the way, the effectiveness of the method has been proved. The model programmes are still continued. Before the continuous and gradual extension of colorectal screening, the validity of the specific method needs to be tested and proved in order to be recognized as a routine procedure for screening. There is a need to test the feasibility of total colonoscopy, however, to this effect the colonoscopic capacity in the country has to be further developed.

Early detection for colorectal cancer: new aspects in fecal occult blood screening

The authors report on promising diagnostic methods of occult intestinal bleeding and discusses the potential new strategy of early detection of colorectal carcinomas in respect to old and new diagnostic measures available. Because of the limited sensitivity and specificity of classical methods used for the demonstration of occult fecal blood, the authors recommend the introduction of new techniques and markers in screening practice. It is presumed that new discoveries in molecular biology will improve the accuracy of early colorectal cancer prevention. Their implementation into routine screening, however, will not take place in the near future. Until their realization, improved screening efficacy is expected from the use of more specific and sensitive blood tests.