[Screening for colorectal cancer: even with virtual colography?]

Colorectal cancer (CRC) is responsible for 27,000 deaths and 65,000 new cancers in Germany each year, although this should be unnecessary as CRC is preventable because it is possible to remove the precursors, harmless polyps and adenomas. However, only 2.5 % of people in health insurance make use of screening colonoscopy annually so that it becomes necessary to check out other screening tests. The most commonly used test is the Guaiak-based test for fecal occult blood (gFOBT) which is highly specific but not very sensitive (only approximately 10 %). New immunological stool tests are more sensitive but the specificity is reduced from 90 % to approximately 80 %. Virtual colonoscopy based on computed tomography (CT) or magnetic resonance imaging (MRI) is comparable to endoscopy for diagnostics with overall accuracy rates of approximately 80-90 % for polyps larger than 5 mm but for radiation protection reasons CT is not usable in Germany and MRI is internationally not adequately established by large study trials. For the future there is much hope in molecular blood tests. It is of great importance that every physician is aware of the different tests, their strengths and weaknesses and advises all patients to use the different screening possibilities.