Seifu, Daniel (PhD)Hadgu, Endale2018-06-212023-11-292018-06-212023-11-292017-07http://etd.aau.edu.et/handle/123456789/2525In this study from Tikur Anbessa Specialized Hospital, 114 breast cancer patients diagnosed between 2012 and 2015 were enrolled. Estroge receptor (ER), Progesterone Receptor (PR), Ki- 67 and Human Epidermal Growth factor (HER-2) receptor status were assessed using immunohistochemistry (IHC) from tissue microarrays (TMA). Fluorescence in situ hybridization (FISH) and Gene Protein Assay (GPA) was used for assessment of gene amplification in all equivocal tumor samples and for confirmation in HER2-enriched cases. Androgen Receptor (AR) was assessed using IHC from TMA and BRCA1 was assessed using IHC from whole section. EBV, HCMV and HPV viral proteins or/and DNA were assessed using IHC or/and multiplex qPCR. The 2013 St. Gallen international panel of expert’s recommendation for classification of breast carcinoma based on IHC was applied to molecularly classify the tumors. Information obtained also included age, tumor grade, histological type, and stage of disease. In this study, the most common molecular subtypes was Luminal A (40%) followed by Luminal B (26%), TNBC (23%) and HER2-enriched (10%). ER were positive in 65% of all tumors and 43% the participants were positive for PR. There was statistically significant variation in median age at diagnosis between the different molecular subtypes (P<0.05). There was a bimodal distribution of molecular subtypes in different age ranges at diagnosis with Luminal B subtype being more common at younger ages (median=36) and Luminal A subtype being more prevalent at older ages (median=42). There were no statistically significant differences in tumor grade, histology, and stage between the molecular subtypes of breast cancer. AR was expressed in 80% of breast cancers, which is higher than the expression rates of both ER and PR. There was a statistically significant variation (P<0.05) in the proportion of AR positivity between ER-positive (93%) and ER-negative tumors (60%). There was a statistically significant variation (P<0.05) in the proportion of AR positive cases between PR-positive (98%) and PR- negative (70%) tumors as well. There was no statistically significant variation in the expression of AR between HER2-positive and HER2-negative tumors in this study (P=0.145). AR expression among TNBC was 48% which is significantly different (P<0.05) than the other molecular subtypes. No statistically significant correlation was found between the clinicopathological parameters and AR expressionenBreast CancerThesis