English

Abstract

BACKGROUND Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity from cancer. The risk group ranges from 69-79 years and the mean age being 62 years. This study was done to assess and compare the clinicopathological characteristics of colorectal carcinoma in adults above and below 50 years and also study the expression of MLH1 for demonstration of microsatellite instability in colorectal carcinoma. METHODS This was a cross-sectional study conducted in the Government Medical College, Trivandrum, Kerala, after obtaining ethical committee clearance (IEC.15/18/2017/MCT dt 19/12/2017). All cases of colorectal carcinomas that had surgical resection and the specimen brought to the Pathology department were included in the study. Carcinomas which were secondary deposits from elsewhere were excluded. Sample size was 61 calculated using the formula n=4pq/d2. Study variables included age, site, histology type, stage, differentiation, lymphatic and vascular spread and lymphocyte infiltration were recorded. Routine H&E sections were used to observe the morphology, invasion, grade, and stage of the tumours. Then MSI was detected using MLH I. Clinical details were collected from the patients and medical records. Data were entered in excel sheets. categorical variables are expressed as proportions and quantitative variables are expressed as mean and standard deviation. Chi square test was used as the test of significance for categorical variables. RESULTS Clinicopathological features of 61 cases were studied and the mean age was 61 years. Most cases were left-sided cancer with moderately differentiated classical adenocarcinoma being the most common histopathological subtype. Individuals less than 50 years presented with adenocarcinoma with mucinous and signet ring cell morphology and with poor differentiation. 67.2 % had no lymphovascular invasion. The majority of the cases were positive for MLH1. The cases which showed negativity for MLH1 were cases with mucinous differentiation or signet ring cell type and were predominantly moderate to poorly differentiated and this relation was found to be significant. CONCLUSIONS The study concludes that the majority of CRC occurred in individuals between 61 - 70 years of age, they were left-sided moderately differentiated adenocarcinomas with stage IIB disease, most were negative for lymphovascular invasion and tumour infiltrating lymphocytes. Younger patients had a higher percentage of mucinous and signet-ring cell histology. 78.7 % were positive for MLH1. KEY WORDS Colorectal carcinoma, MLH1, Microsatellite instability