Colorectal cancer (CRC) is the third most common cancer worldwide. The most common form of hereditary cancer is Lynch syndrome which accounts for ∼1%–3% of all CRC burden. These alterations pave the way to Microsatellite Instability (MSI).Microsatellite instability is the result of defect in DNA mismatch repair which results in repeat length polymorphism of a microsatellite marker, resulting in DNA hypermutability. Carcinoembryonic antigen (CEA) serves as the most cost-effective & widely used tumor marker in colorectal cancer. Influence of genetic instability on tumor marker expression is not known. Thus, the aim of this study was to investigate the role of microsatellite instability (MSI) & CEA serum levels in hereditary CRC.
Forty one patients (18years to above 70 years) were included in this study after confirmed endoscopic examinations. A detailed clinical history was taken. The signs and symptoms of these patients have been critically observed along with their serum CEA level before surgery & immediate after surgery. DNA from the extracted tumors was investigated for MSI. Mutational analysis of the above said genes is still continuing. MSI screening was carried out by PCR-SSCP.
From the present study, of the cases 29.27% (12/41) was familial CRC whereas 70.7% (29/41) was sporadic.Most frequently detected colorectal cancer was in 40-49 years age group (29.27%) with 65.85%male and 34.15% females. CEA showed a significant association with TNM staging, tumor size and smoking habit (p < 0.05) but did not show any significance with sex and site of cancer (p > 0.05). Microsatellite instability was observed in approximately 60% of the populations. Overall, significant association was observed with germline MSI and CEA expression (p value: 0.004). Significant association was observed with germline MSI status with MSH2 and MLH1 mutation (p value: 0.023).
For both familial as well as sporadic colorectal carcinoma, besides CEA, microsatellite instability can be used as a prognostic marker for disease progression.
Clinical trial identification
All authors have declared no conflicts of interest.