Comparative Study of DNA ploidy and BRAF Immunohistochemistry between Colonic Adenocarcinoma and Inflammatory Colonic Lesions

Abstract

Objectives: To evaluate DNA ploidy and S-phase fraction (SPF) in non-Lynch colonic adenocarcinoma, ulcerative colitis (UC), Crohn disease (CD) which are known as risk factors, and colitis. We correlated ploidy and SPF with tumor grading, staging and BRAF expression. Methods: All studied adenocarcinomas have intact mismatch repair genes as proved by immunohistochemistry. All were assessed for ploidy by automated image-based DNA cytometry and histograms were drawn. Immunostaining by anti- BRAF V600E was performed. Diagnostic laparoscopy (DL) was done as a preliminary step for staging GI cancers. Results: there is significant difference in DNA ploidy between groups; 77.5% and 17.5% of aneuploid cases are adenocarcinoma and UC. Groups are compared in terms of 2C, 4C, above 4C DNA content and SPF and significant difference is principally found between adenocarcinoma group and others. In adenocarcinomas, DNA ploidy is significantly correlated with tumor staging and grading. Regarding BRAF expression, there is significant difference between groups; all adenocarcinomas, 83.33% of UC were positive, while all cases of colitis, bilharzial colitis, CD were negative. There is significant relation between BRAF and SPF among all diploid cases including adenocarcinoma, and among non-neoplastic diploid cases. There is direct significant relation between BRAF intensity and adenocarcinoma staging. There is no significant difference between BRAF and ploidy among UC cases, although 75% of aneuploid UC are positive. DL helps in GI cancer staging. Routine laparoscopy before laparotomy, especially in cancers which have equivocal operability helps to avoid unnecessary laparotomies. Conclusion: Based on significant difference in ploidy between adenocarcinoma and UC and between SPF and ploidy, assessment of ploidy by DNA cytometry for UC and other colitis could therefore predict impending malignant transformation before development of colonic dysplasia. Also measuring SPF in adenocarcinoma helps to select patients who could greatly benefit from chemotherapy. DL has vital role in staging GI cancers.