Immunohistochemical profile and age distribution of breast cancer at a tertiary referral center in Abuja, Nigeria: A two-year retrospective study.

e13116 Background: Breast cancer outcomes in sub-Saharan Africa are often poor, driven by late presentation and aggressive tumor biology. Immunohistochemistry (IHC) plays a critical role in guiding treatment; however, data on tumor subtype distribution in Nigerian populations remain limited. This study describes the socio-demographic characteristics and IHC patterns of breast cancer patients managed at the National Hospital Abuja and examines the association between age and tumor biological subtype. Methods: A retrospective descriptive study was conducted among 425 breast cancer patients diagnosed between 2024 and 2025 at the National Hospital Abuja. Data on age, sex, and IHC subtype were extracted from pathology records. Tumors were classified by Scarff–Bloom–Richardson (SBR) grade and receptor status. Associations between age groups (≤30, 31–40, 41–50, ≥51 years) and IHC subtypes were analyzed using chi-square statistics. Results: The mean age at diagnosis was 49.6 ± 13.3 years in 2024 and 47.8 ± 12.0 years in 2025, with the highest burden observed among women aged ≥51 years (41.9%). Females accounted for 96.5% of cases. Triple Negative Breast Cancer (TNBC) was the predominant subtype, comprising 58.8% of all tumors (48.7% SBR II and 10.1% SBR III). Hormone receptor–positive tumors (ER/PR positive) accounted for 33.4%, while HER2-positive tumors were rare ( < 3%). TNBC remained the dominant subtype across all age groups, including younger women, with no statistically significant association between age and IHC subtype (χ² = 32.68, p = 0.208). Conclusions: Breast cancer in this Nigerian population is characterized by a striking predominance of aggressive TNBC across all age groups, with low rates of hormone receptor and HER2 positivity. The absence of age-related differences in tumor biology suggests widespread aggressive disease irrespective of age. These findings highlight the urgent need for improved early detection, expanded diagnostic capacity, and context-specific treatment strategies to improve breast cancer outcomes in Nigeria.