Background: Human Epidermal Growth Factor (Her-2/neu) has strong therapeutic implications in certain cancers like breast and gastric cancer. Literature on its frequency in colorectal cancer is scarce. In this study, we have investigated the frequency of Her-2/neu expression in colorectal adenocarcinomas and its association with various clinicopathological variables.
Methods: A total of 95 patients who underwent colonoscopic biopsy or colectomy were studied after Institutional Ethical Approval. Hematoxylin & eosin (H&E) staining was performed on all the tissue sections. Expression of Her-2/neu was investigated by immunohistochemistry using α-Her-2 antibody. In order to quantify Her-2/neu expression, three criterias were applied that includes the pattern of staining, intensity of staining and percentage of tumor cells stained. Furthermore, its association was seen with various clinicopathological variables including age, gender, histopathological type, grade and stage of the tumor. Data was entered and analyzed using SPSS version 21. A p-value of < 0.05 was considered as significant.
Results: From the total of 95 cases, 75 (78.9 %) cases showed Her-2/neu expression. Pattern of Her-2/neu staining was significantly associated with the grade of colorectal cancer depicting cytoplasmic Her-2/neu expression higher in low grade (50 %) while membranous Her-2/neu expression more in high grade colorectal cancer (45 %) (P-value = 0.030). Pattern of Her-2/neu staining was also significantly associated with the type of colorectal cancer representing membranous Her-2/neu expression to be more common in mucinous type (38.5 %) while cytoplasmic Her-2/neu expression to be more frequent in non mucinous type (42.7 %) of colorectal cancer (p-value = 0.024). We observed a significant association between percentage of cells stained & tumor type, with score 3+ maximum in non mucinous type of colorectal cancer (p-value = 0.006).
Conclusion: Her2/neu is considerably expressed in colorectal adenocarcinoma in Pakistani population. Our findings indicate a significant strong association of cytoplasmic Her-2/neu expression with low grades and membranous Her-2/neu expression with high grades of colorectal cancer. These findings add to the body of information & may help in conducting clinical trials in future to explore its therapeutic significance as well.
Keywords: Colorectal adenocarcinoma; Her-2/neu; Immunohistochemistry; Trastuzumab.