The Histological Subtypes of Breast Cancer Seen in a Tertiary Hospital in South-East, Nigeria

INTRODUCTION: Breast cancer is a disease with heterogeneous nature that may have different prognosis and respond to therapy differently despite similarities in histological type, grade and stage. It is common among women in both developed and developing countries of the world. MATERIALS AND METHODS: This study was a 2-year retrospective study involving a systematic analysis of all the formalin-fixed paraffin-embedded tissue blocks previously diagnosed as breast cancers. The study occurred at the Department of Morbid Anatomy, University of Nigeria Teaching Hospital, Enugu. We retrieved all the archived tissue blocks and subjected them to further ancillary testing using the immunohistochemistry monoclonal antibodies: (Oestrogen receptors (ER), Progesterone receptors (PR) and Her-2 neu antibodies). RESULTS: Out of 417 cases of breast cancer analysed, four hundred and Ten (410) were females representing 98.3%, seven (7) were males representing 1.7%. The mean age of all subjects in this study was 45.1±10.2 SD (years). The age of patients ranged from20 to 70 years. The age group 31 to 40 years showed the highest number of cases, 133 (32.4%). The cases positive for ER were 157 (37.6%), while 260 (62.4%) were negative. The cases positive for PR were 144 (34.5%) and 273 (65.5%) were negative. Fifty-four cases (12.9%) were HER2-neu positive, 15 (3.6%) were equivocal and could not be further analysed due to lack of the facility to do Fluorescence in-situ hybridisation, and 348 (83.5%) were HER-neu negative. Phenotypic classification based on ER, PR, and Her2 immunohistochemistry showed 113 cases (27.1%) were Luminal A, 45 cases (10.8%) were Luminal B, 23 cases (5.5%) were Her2 Enriched, 236 cases (56.6%) were Basal-like/Triple-negative, and none (0%) was Normal-like. CONCLUSION: In conclusion, this study shows that Basal-like/Triple-negative breast cancers are most common and are seen more in premenopausal women in Enugu.