Artikel
Blood markers for early detection of colorectal cancer. A systematic review
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Autoren
Veröffentlicht: | 6. September 2007 |
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Gliederung
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Background: Despite different available methods for colorectal cancer (CRC) screening and their proven benefits, morbidity and mortality of this malignancy are still high, partly due to low compliance with screening (about 70,000 new cases and 30,000 deaths per year in Germany). Minimally invasive tests based on the analysis of blood specimens may overcome this problem.
Methods: We searched the MEDLINE database for relevant studies published until November 2006. Information on the markers under study, on the underlying study populations and on performance characteristics was extracted. Special attention was given to performance characteristics by tumor stage.
Results: Overall, 97 studies evaluating 74 different markers were included. Most studies have been done on protein markers (71 studies, 54 different markers) and RNA markers (20 studies, 13 different markers). Genetic and epigenetic markers were assessed in 6 studies and cytological assays were investigated in 3 studies. Performance characteristics varied widely between different markers, but also between different studies using the same marker. Promising results were reported for some novel assays, e.g. assays based on SELDI-TOF MS or MALDI-TOF MS, for some proteins (e.g. soluble CD26 and bone sialoprotein) and also for some genetic assays (e.g. L6 mRNA), but evidence so far is restricted to single studies with limited sample size and without further external validation. In addition only very few studies examined sensitivity of markers among patients bearing adenomas. As regards controls, they had often not undergone colonoscopy.
Discussion: Larger prospective studies using study populations representing a screening population are needed to verify promising results. In addition, future studies should pay increased attention to the potential of detecting precursor lesions. Furthermore practical issues and costs need to be considered, because screening for colorectal cancer is typically implemented as a population-based, mass screening program.