Introduction: With the advent of era of targeted cancer therapy, the serious side effects of chemoradiotherapy have been minimised. Considering the success story of anti-HER2/neu drugs in breast cancer oncology, the present study was conducted. The study evaluates the immunohistochemical expression of HER2/neu in endometrioid cancer among Iraqi patients. Aim: To assess the immunohistochemical expression of HER2/neu in endometrioid carcinoma of uterus and to find the relationship of this expression with FIGO stage and grade and with patient age. Materials and Methods: In this cross sectional study, formalin-fixed, paraffin-embedded tissue blocks of 62 hysterectomy specimens that were diagnosed as endometrioid carcinoma in the teaching laboratories in the Medical City complex, Baghdad were retrieved and assessed by three pathologists using the same scoring system for HER2/neu as in breast cancer with positivity regarded as +2 or +3. Statistical correlation using Chi-square test analysis was done. Results: Out of 62 cases of endometrioid carcinoma, 30 (48.38%) were positive for HER2/neu and a significant statistical relationship between expression of this marker with histological grade and patient age was seen. The cases which were immunohistochemically positive for HER2/neu were closely associated with high grade morphology and patients younger than 40-year-old. Conclusion: Endometrioid carcinoma is a type of endometrial adenocarcinoma commonly having a well differentiated morphology (Grade I) and low stage at presentation. The study concludes that young patients with a high grade endometrioid carcinoma would hopefully benefit from the application of targeted anti-HER2/neu therapy in future.
