ABSTRACT
Colorectal adenocarcinoma is the most common type of gastrointestinal cancers in Iraq, and according to the Iraqi cancer registry [ICR] reports, the incidence of colorectal carcinoma was 2.99% of whole body malignancies [ICR 2010]. In males, it's the 5[th] common cancer while in females it's the 4[th] most common cancer. Her2/neu is an important oncogene in breast cancer, but its prevalence and significance in colorectal carcinoma have been documented. To determine the frequency and the pattern of Her2/neu expression in colorectal adenocarcinoma by immunohistochemical technique and to correlate this expression with different clinicopathological parameters. Twenty five cases of colorectal adenocarcinoma were studied, these cases were diagnosed in private laboratories in Baghdad/Iraq from November 2011 to march 2013. Clinicopathological parameters such as age, gender, pathological diagnosis, including the tumor site, size, lymph nodes status, grade and stage of tumor were taken from patients file. Sections of 4 µm stained by H and E stain and immunohistochemical stained for Her2/neu. Using infiltrative ductal carcinoma of the breast as control positive, evaluation of Her2/neu expression by immunohistochemistry in all cases was performed. Fourteen [56%] of the cases were males, 11 [44%] case were females, with age distribution ranging from [24-89] years, with a mean age of 56.5 years. Tumor size ranges between 2.5-10 cm, with mean of 6.25 cm. Seven [28%] cases were localized in the cecum, 5 [20%] from each rectum, sigmoid and left colon, respectively and 3 [12%] involving more than one segment of the colon. Histologically the tumor grade ranges from moderately differentiated in 23 [92%] cases and poorly differentiated in 2 [8%] cases. Regarding pathological staging [TNM system], 5 [20%] were stage T2, 17 [68%] were stage T3 and 3 [12%] were T4. Lymph node involvement found in 10[40%] of the cases and distant metastasis was found in 2 [12%] cases. Her2/neu expression was present in 4[16%] cases of 25 colorectal adenocarcinoma; there was no correlation with age, sex, histopathological grade, location, lymph nodes status and tumor invasion. Concerning data exists about the prevalence of her2/new expression in colorectal adenocarcinoma, there was no significant correlation between her2/neu over expression and tumor size, grade, localization of the primary tumor, lymph nodes status and depth of invasion