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Summary Colorectal cancer (CRC) is the second cause of cancer-related mortality although its early detection allowed the survival rate to increase up to 90 %. The most common screening test in France is the classical fecal occult blood test (Hemoccult ® ) performed in families and individuals at risk, and now systematically every two years in individuals after 50 years. New biomarkers have yet appeared, particularly with the detection of hypermethylated DNA in stools or blood plasma. Gene methylation is an epigenetic phenomenon often associated with carcinogenesis, especially CRC, DNA extracted from normal tissues being not or poorly methylated, allowing the normal transcription of the gene and the expression of the protein. Recently, a new plasma assay detecting methylated DNA of a septin variant (Sept9 assay) was developed. Septins are proteins from the cytoskeletal, linked to microtubules and actin fibers; they are GTPases associated with a number of cellular functions such as cytokinesis and vesicular trafficking. They form a great family with at least 13 members that are assembled into hetero-oligomers forming filaments and rings. Among ubiquitous septins, septin9 was rapidly associated with CRC with the development of a blood-based assay (« septin9 DNA methylation assay » from Epigenomics), sensitive and specific, allowing the screening quality to be improved with better compliance in targeted populations. Septin9 assay detects adenomas (polyposis) of more than 1 cm (generally not cancerous), increases in positivity in function of the evolution stage (stages I to IV), and remains negative in normal individuals as verified with colonoscopy. This new non stool-based assay could compete with stool-based assays in development such as immunologic detection. |
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