Histopathological profile of triple negative breast carcinomas seen in patients in National Hospital, Abuja over a 10-year period (January 2010 - December 2019)

BackgroundTriple negative breast carcinoma (TNBC) cases in Africa and the black race which are most commonly seen among the reproductive age group are highly aggressive and have a high mortality rate. Based on its protein expression using immunohistochemical methods it does not express the hormone receptors (oestrogen and progesterone) and the human epidermal growth factor receptor 2 (HER2). As a result the only means of treating TNBC patients so far is by conventional chemotherapy +/- radiotherapy. Even then only 50.0 % of these patients will respond to the chemotherapy. Further studies which may help improve treatment and survival in these patients are important. ObjectiveThis study is aimed at knowing the histopathological profile of TNBCs in Abuja with the expression of androgen receptor; an important marker in these patients. MethodTwo hundred formalin-fixed paraffin embedded TNBC tissue blocks were selected for the study. The histological type and their respective histological grades (based on the Nottingham grading system) were noted from the haematoxylin and eosin(H&E) sections. Immunohistochemical staining was done using antibodies against androgen receptor (Biocare) and CK5/6 (Invitrogen) with in-house controls. The androgen receptor and CK5/6 expressions were analysed using a semi-quantitative scoring method: - A tumour was considered positive for LAR if [≥] 1.0 % of tumour cell nuclei were staining and positive for CK5/6 if [≥]10.0 % of tumour cells had membrane staining. Other biographic data like tumour size, presence or absence of lymphovascular permeation were also analysed. Correlation between the histological types and grades were also done using SPSS version 21 statistical package. ResultsThe 30-49 age group had the highest frequency of TNBC. The commonest histological type seen among TNBCs is Invasive carcinoma; NST at 93.0%. The most frequent histological grade is grade 2 at 56.0 %. The androgen receptor subtype constituted 19.0 %. The basal subtype formed 28.5 % of the total sample size. There was no significant correlation between the histological type and grade of TNBC. 73.3% of the patients had tumour size of pT1 and pT2. ConclusionThis study shows that the percentage of androgen positive cases among triple negative breast carcinomas is significant enough to warrant routine luminal AR testing for TNBCs. Furthermore, this study has shown that the most frequent histological type is Invasive carcinoma; Non-specific type (NST) regardless of the molecular subtype and presence or absence of lympho-vascular permeation. It has also shown that the most frequent histological grade seen among patients with TNBCs is Grade 2.