Distribution of Immunohistochemical Subtypes of Breast Cancer in Nigeria: A Systematic Review

Breast cancer remains the most common cancer seen in women worldwide. Great strides have been made in its management even in low- and medium-income countries such as Nigeria. Immunohistochemistry is essential in planning treatment, with the increasing availability of hormonal and other targeted therapies. This systematic review aims to review the immunohistochemical subtypes of breast cancer seen in Nigeria. A literature search was done on PubMed, Google Scholar, and African Journal Online databases for publications on the immunohistochemical subtypes of breast cancer in Nigeria using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Articles were selected on the basis of their relevance to immunohistochemistry of breast cancer in Nigeria. A total of 17 studies published between 2005 and 2024, comprising 3,017 patients, met the inclusion criteria. Geographically, most were from the South West region (n=8), followed by South South (n=4), North Central (n=3), and one each from the South East and North West. Sixteen studies, with a total of 2,846 subjects, reported hormone receptor status. Estrogen receptor-positive (ER+) rates ranged from 10.9% to 65.1%, progesterone receptor-positive (PR+) rates from 12.5% to 70.7%, human epidermal growth factor receptor 2-positive (HER2+) rates from 5.2% to 62.5%, and triple-negative breast cancer (TNBC) rates from 12.2% to 79.3%. Ten studies (n = 2,220) reported molecular subtypes, with luminal A subtype ranging from 4.7% to 61.9%, luminal B from 2.1% to 22.8%, and Basal-like cancers ranging from 12.5% to 40.7%. Regional analysis revealed the highest ER and PR positivity in the South West and the lowest in the South South region of the country, where TNBC and HER2+ tumours were relatively higher. This review provides an up-to-date synthesis of immunohistochemical subtype distribution of breast cancer in Nigeria, highlighting marked regional variability. The predominance of ER+ and luminal A subtypes supports the role of endocrine therapy in many patients, while high TNBC prevalence in certain regions underscores the need for improved access to chemotherapy and novel targeted treatments. These findings reinforce the importance of incorporating local epidemiological patterns into personalised breast cancer management strategies.