Abstract :
Introduction: KRAS mutation occurs in colorectal cancers in about 35%-45% cases. Colorectal carcinoma develops from precursor lesions and KRAS mutations occur early in carcinogenesis. KRAS mutation status can help to predict the course and also determine optimal adjuvant therapy.
Aims and Objectives: To detect the presence of KRAS mutations in the deoxyribonucleic acid (DNA) isolated from tissue of colorectal carcinomas and precursor lesions and infer the rate of positivity and negativity of these mutations and correlate them with the type and grade of lesion.
Materials and Methods: This was a retrospective hospital based study done in three years (2009 to 2012) at MGM Hospital, Warangal. Tissue from precancerous lesions and diagnosed cases of colorectal carcinomas was studied for histopathology; and for KRAS mutation by PCR-SSCP.
Observations and Results: On histopathology, there were 35 cases of adenocarcinomas, 21 (60%) being well differentiated, 9 (25.7%) and 3 (8.5%) being moderate and poorly differentiated and 2 cases (5.7%) being mucinous carcinoma. PCR-SSCP was performed on 32 cases. 9 cases (33.3% adenomatous polyps and 38% adenocarcinomas) were positive. The KRAS mutation positivity was 50% for poorly differentiated colorectal adenocarcinoma and was 33% each for both well and moderately differentiated adenocarcinoma.
Conclusion: In our study, 38% of colorectal adenocarcinomas and 33.3% of adenomatous adenomas were positive for KRAS mutation. As KRAS has a role in adenoma-carcinoma sequence, and also considering the treatment aspects, we recommend KRAS mutation study for above lesions.
Keyword :
Adenomatous polyps, Colorectal adenocarcinomas, KRAS mutation, PCR-SSCP