Profile of HER2/neu Expression in Surface Epithelial Ovarian Tumours: A Clinicomorphological Study

Introduction: Surface Epithelial Ovarian Tumours (SEOT) are most prevalent tumours and account for about two third of all ovarian cancers. Survival of ovarian carcinoma is poor despite optimal surgical and chemotherapeutic management. Evaluation of new diagnostic and prognostic Immunohistochemical (IHC) markers will be essential in this aspect. Aim: To evaluate quantitatively the profile of Human Epidermal growth factor Receptor 2 (HER2)/neu IHC expression with standard scoring system in SEOTs and their association with various clinicpathologic variables (age, laterality, CA 125 levels, histological subtype and FIGO staging). Materials and Methods: The present ambispective study was done in the Department of Pathology, SRM Medical College Hospital and Research Centre, Kattankulathur, Tamil Nadu, India, from August 2020 to August 2022 with a sample size of 166 cases. All the histopathological samples of SEOT during the study period from August 2020 to August 2022 (prospective) and all borderline, malignant and few benign cases from June 2016 to August 2020 (retrospective) were also included in the study. Cases for which slides and blocks were not available and patient treated with neo adjuvant chemotherapy or radiotherapy were excluded in the study. For prospective cases after getting clinical history and Cancer Antigen 125 (CA 125) level, specimens were fixed, processed and Haematoxylin and Eosin (H&E), IHC staining was done as per standard lab protocol, for retrospective cases clinical history, CA 125 levels, pathological diagnosis and tissue blocks were retrieved, IHC performed and finally both prospective and retrospective cases HER2/neu IHC expression association was studied related to clinicopathological parameters. Results: Out of total sample, SEOT was the most common (n=184, 76.98%) tumour cases, followed by germ cell tumours (n=42, 17.57%) cases and least common was sex cord stromal tumour (n=13, 5.43%). HER2/neu had higher IHC expression in malignant tumours and showed statistically significant positive association with age (p-value=0.001), CA 125 level (p-value -0.001), and histological diagnosis (p-value <0.001), but there is no significant association with size of tumour (p-value=0.786), parity (p-value=0.717), laterality (p-value=0.514) and the International Federation of Gynecology and Obstetrics (FIGO) grading (p-value=0.274). Conclusion: Malignant tumours had high HER2/neu IHC expression, thus emphasising its carcinogenic role and helps in the diagnostic differentiation of benign and borderline tumours with malignant potential from actual malignant tumours and can be a therapeutic target in future.