Triple-negative Breast Cancer (TNBC) and Its Luminal Androgen Receptor (LAR) Subtype: A Clinicopathologic Review of Cases in a University Hospital in Northwestern Nigeria

Background: Breast cancer (BC) is a common malignancy; the most frequent in Nigeria. BC characteristically exhibits great biologic diversity. Amongst its variants, the triple-negative subtype is also characterized by heterogeneity (thus making it a study in diversity within diversity) and also by some unique clinicopathologic features including clinical aggressiveness, lack of response to current targeted therapies, and tendency to cluster amongst young premenopausal women especially in populations of women of African ancestry. Aims: The objective of this study was to conduct a retrospective clinicopathologic survey of all breast carcinomas to profile the triple-negative breast cancers (TNBCs) amongst them and illustrate their immunohistochemical pattern of luminal androgen receptors (LARs) expression. Patients and Methods: All the cases entered into the departmental records as breast carcinomas over the study period were extracted including patients' request cards, hematoxylin and eosin-stained slides, and paraffin-embedded tissue blocks of those diagnosed as triple-negative cancers. These were immunohistochemically stained using a monoclonal antibody for androgen receptor (AR). The whole data were analyzed and presented in tabular formats. Results: A total of 660 breast carcinomas of which 89 (13.48%) cases were identified as TNBCs with a mean age of occurrence of 42.89 ± 11.88 years. Most TNBCs (95.5%) were carcinoma no special type and 61.8% had low or intermediate histologic grading. LAR expression was noted in 11.24% of the TNBCs. Conclusion: Triple-negative cancer in this study shares some of the known characteristics but also portrays some divergence from the commonly described features.