Hormonal and HER2 Receptor Immunohistochemistry of Breast Cancer in North-Eastern Nigeria: a preliminary report

Background: Morphologically identical breast carcinoma can display divergent clinical outcomes and response to therapies, withdifferences in incidence, clinical picture and mortality rates across various patient populations. This could be attributed to differences in the molecular characteristics of the carcinoma. Recently, gene expression profiling and its surrogate Immunohistochemistry (IHC) markers classified breast cancer into 4 molecular subtypes, and these receptor-defined subtypes are a major determinant of treatment options and disease outcomes. However, there remains an uncertainty regarding the frequency of the various subtypes in Africa. To date, there has been no comprehensive study of the molecular subtypes of breast cancer in our environment. Objective: To conduct a preliminary study on Estrogen (ER), Progesterone (PR) and Her2 receptor status of breast cancers at the University of Maiduguri Teaching Hospital, North-Eastern Nigeria. Materials and Methods: A prospective study spanning three years and four months was done on breast cancers seen at a surgical unit at the University of Maiduguri Teaching Hospital, from November 2012 to March 2016.Standard histological and immunohistochemicalanalysis were done for ER, PR and Her2 status. Results: A total of 50 cases of breast cancer were seen in the unit over a period of three yearsand four months with an age range of 20 – 75 years, and a mean age of 46.1 ±13.4 SD (years). Of these, 38 had available Immunohistochemistry results for receptorstatus. Proportion of ER+, PR+ and Her2+ tumors were 36.8%, 34.2% and 21.1% respectively. Phenotypic classification based on ER, PR and Her2 immunohistochemistry showed that more than half were Triple Negative (52.6%, 20/38), while 10 cases (26.3%) were Luminal Type A, 5 cases (13.2%) were Luminal Type B, and 3 cases (7.9 %) showed overexpression of Her2. Conclusion: We observed that breast cancer in our cohort occurs at a young age group, mostly premenopausal, with more than half of the patients having thetriple negative phenotype. While a significant proportion are ER positive, majority are hormone receptor negative, favoring chemotherapy over hormonal treatment. There is need for effective screening programs, and immunohistochemistry of breast cancers should be standard and routine.