Microsatellite instability (msi) causes hereditary non-polyposis colorectal cancer (hnpcc), and occurs in about 15 per cent of sporadic colorectal cancers. one of the reasons of the microsatellite instability (msi) status assessment is be as a prognostic marker. we assessed the role of msi status in survival of individuals diagnosed with primary colorectal cancer.
Methods
In this study the msi analysis was performed on 258 formalin-fixed paraffin-embedded tumors and their matched normal tissues from patients who underwent curative surgery.
the pentaplex panel including 5 quasi mononucleotide microsatellite markers (nr-21, bat-26, bat-25, nr-27 and nr-24) for determination of msi status was used.
cox proportional hazard modeling was performed to assess the clinical prognostic significance.
Results
The subjects were subdivided into three groups by msi testing: msh, msl, mss.
of 258 patients, msh, msl, and mss phenotypes were 40(%15.5), 49(%19), and 169(%65) respectively.
we found that msi-h colorectal cancer were located predominantly in proximal colon sites versus rectal sites, associated with poorer differentiation and tnm stage ii/iii of tumors.
based on our results in crc patients with stage ii, msi-l showed significantly poorer survival compared with patients who had msi-h or mss tumors.
Conclusion
This study suggests that the clinical prognostic role of msi status is dependent on stage and location of the tumor. it seems that, msi-l characterizes a distinct subgroup of crc patients who have a poorer clinical outcome.
