ABSTRACT
Background: Breast's Invasive Ductal Carcinoma (IDC), which is the commonest type of malignancy in females worldwide, can be characterized using immunohistochemistry in view of personalized cancer therapy. In this study, we aimed to determine the pattern of immunohistochemical profiles of IDC using oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 receptor (HER2) and proliferative index (Ki-67) biomarkers in our tertiary healthcare facility in Uyo, Akwa Ibom State, Nigeria given the dearth of its data in our environment. Materials and methods: We carried out a retrospective hospital-based immunohistochemical study of archival IDC tissue blocks over a four- and half-year period. Using systematic random sampling method, 64 formalin fixed paraffin embedded (FFPE) IDC tissue blocks were selected for this study. We carried out immunohistochemical evaluation using ER, PR, HER2 and Ki-67 biomarkers. Subsequently, we presented the results and classification schemes as text, tables, graphs, and photomicrographs. Results: We found that the proportion of expressions were ER-negative (88.7%), PR-negative (87.3%), HER2-negative (68.3%) and Ki-67 (<20%) being 83.6% respectively. The immunohistochemical-based classification which was done using combined immunohistochemical profiles of ER/PR/HER2 and ER/PR/HER2/Ki-67 biomarkers respectively, revealed five immunohistochemical-based subtypes. These subtypes were ER-positive luminal A (ER+/±PR+/HER2-) [5.56%], ER-positive luminal B (ER+/±PR+/HER2+) [5.56%], HER2-overexpression (ER-/±PR+/HER2+) [16.66%], Triple negative (ER-/PR-/HER2-) [66.67%] and Unclassified subtypes (ER-/PR+/HER2-) [5.56%]. Furthermore, these five subtypes were further subcategorized into low (Ki-67 <20%) and high (Ki-67 ≥20%) proliferation subtypes accordingly. Conclusion: The commonest pattern of immunohistochemical profile expression of IDC in Uyo was found to be the Triple negative subtype.