The OncoDefender-MMR test helps physicians assess the prognosis for individual colorectal cancer (CRC) patients; OncoDefender-MMR helps physicians decide which treatment strategy is required based a patient’s individual prognosis.
Recent advances in molecular diagnostics and genomics have revealed that colorectal cancer is not a single disease but in fact consists of three very different types of colorectal cancer disease. Independent of whether colorectal cancer is diagnosed at stage 1, 2, 3 or 4, the type of colorectal cancer a patient has is of enormous medical importance in defining tumor aggressiveness, determining aggressiveness of each type way each type that exhibit chromosomal instability (CIN), microsatellite instability (MSI), or CpG island methylation, (Ogino and Goel 2008), with overlap between the groups.
The Mismatch Repair System (MMR) is responsible for the detection and correction of insertion/deletion mutations of short tandem repeat sequences and single base pair mismatches that occur during cell division. Failure of the MMR system may result from an inherited mutation in an MMR gene, a somatic mutation in an MMR gene, epigenetic suppression of MMR gene function, or a combination of the above any of which leads to microsatellite instability (MSI-H). Several studies1 have shown that MSI-H tumors have a more favorable prognosis and are less prone to lymph node and systemic metastasis.1
MSI-H status has been shown to correlate with CRC patient survival. A meta-analysis of 7,642 CRC patients from 32 studies, including 1,277 MSI-H patients, revealed that MSI-H tumors were associated with better prognosis than MSS tumors (hazard ratio for overall survival was 0.65)2.
- MSI-H was an independent prognostic marker associated with a favorable outcome in CRC and these tumors were less prone to lymph node involvement and systemic metastases.
- Several studies support this further by confirming that only 4% of MSI-H tumors exhibit metastatic disease vs. 15-17% of MSS tumors.
- CRC tumors harboring a V600E BRAF mutation are associated with an unfavorable outcome. While MSI-H CRC without an associated BRAF mutation has a favorable prognosis, patients showing MSI-H and a BRAF mutation have a prognosis similar to MSS CRC.
1,2 College of American Pathologists, Prognostic Uses of Microsatellite Testing, May 12, 2011
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