ThP1.10 - Expression Pattern of Arginase In Tumour Tissue In Male Breast Cancer

Abstract Aim To study the expression pattern of arginase in tumor tissue of male breast cancer (MBC) by immunohistochemistry (IHC). Methods We retrospectively analysed the data of 21 MBC patients who were treated in our centre from January 2018 to March 2022. Immunohistochemical analysis of arginase expression was performed in tumor and lymph node tissue with primary arginase-1 antibody (1:300 dilution). Results The mean patient age was 57 years (33–81 years). 10 patients (48%) had metastatic disease at presentation, while early breast cancer (EBC) and locally advanced breast cancer (LABC) constituted 19% and 33%, respectively. Invasive ductal carcinoma was the predominant histology, with luminal being the major subtype. Modified radical mastectomy was done in 9 patients (43%), and palliative chemotherapy was given to all metastatic patients. IHC analysis revealed a lack of arginase expression in the tumor tissue even though it was expressed in the surrounding neutrophils. Conclusion Contrary to the majority of existing literature, ours was an IHC-based study, which provides a more accurate estimation of arginase expression at the cellular level. The lack of arginase expression obtained in our study may point towards the non-expression of the enzyme in MBC. This suggests that arginase is not a tissue biomarker in MBC. Taking other studies with protein expression into account, arginase should be treated, if necessary, only as a blood biomarker.