Study on Prognostic Implications of HER2/Neu Expression in Colorectal Cancer in Eastern India

Author(s): Mitu Mohanty1 , Debahuti Mohapatra2

BACKGROUND Colorectal cancer (CRC) is the third most common malignancy with high mortality rate and majority of them are diagnosed with endoscopic biopsy. Further, it requires markers to predict survival and treatment. Human epidermal growth factor receptor 2 (HER2) is a member of the epidermal growth factor receptor family having tyrosine kinase activity. Its gene amplification and over expression play an important role in the development and progression of certain cancer types. Targeted therapy against HER2/neu positive cases is well-established in breast and gastric carcinoma but its prevalence and significance in colon cancer is not well documented. We wanted to evaluate the commonest location of colorectal cancer, its prevalence as per age, sex, morphological type, and expression of HER2/neu by immunohistochemistry (IHC). METHODS A total of 84 paraffin wax embedded colonoscopy biopsies were studied which comprised of neoplastic lesions, out of which 46 cases of CRC were studied for HER2/neu IHC and scoring was done according to the ASCO/CAP (American Society of Clinical Oncology / College of American Pathologists) for HER2 Test guideline recommendation 2013. RESULTS The commonest cancer was adenocarcinoma NOS type; predominantly seen in the left side of colon; in patients over of 50 years of age with male preponderance. Out of 46 cases included for IHC, expression of HER2/neu with positive score 3+ (6.52%), having cytoplasmic and membranous staining was seen in moderately and poorly differentiated adenocarcinoma. Equivocal score 2+ (26.09%) with membranous staining was found in moderately differentiated adenocarcinoma. CONCLUSIONS Due to prominent membranous staining in higher stages and grades of colorectal cancer, Herceptin therapy could be helpful in patients with distant metastasis.