Abstract
Sub-Saharan African women face a high burden of breast cancer, influenced by genetic and lifestyle factors. However, the lack of comprehensive, age-stratified data hinders the identification of risk factors and the development of effective, population-specific interventions. This study aimed to assess age-related variations in breast cancer prevalence among Nigerian women, providing insight into associated risk factors and disease trends. A retrospective review of 3,263 breast histopathology records (9.46% of total from 2015 to 2023) was conducted. Lesions-benign and malignant-were analyzed across five age groups: children and adolescents (0-19), young adults (20-39), middle-aged (40-59), higher-aged (60-79), and elderly (≥ 80), using MS Excel and GraphPad Prism 8.0. Statistical comparisons were performed by age and lesion type. Most cases were in young adults (45.97%) and middle-aged women (33.83%). The left breast was more commonly affected (46.86%) and had higher malignancy rates than the right (44.41%) or bilateral lesions (7.20%). Benign lesions were predominant (56.76%), especially among young adults (57.34%). Malignancy incidence increased with age, peaking in middle-aged women (53.30%). Fibroadenoma was the most frequent benign lesion in children and adolescents and young adults, while fibrosis predominated in middle age. Invasive ductal carcinoma (IDC) was the leading malignant subtype, with a sharp rise by 2023-particularly among middle-aged (172 cases) and young adult women (71 cases). Among 339 immunohistochemically profiled cases, triple-negative breast cancer (TNBC; 42.77%) and ER+/PR+ tumors (36.87%) were most common. TNBC was the only subtype detected in children and adolescents. Middle-aged women bore the highest burden of all subtypes, with a marked increase in TNBC and ER+/PR+ cases in 2023. The rising incidence of aggressive subtypes, particularly TNBC, highlights the need for enhanced molecular diagnostics and personalized therapies. Age-specific trends reinforce the urgency for targeted screening, especially for young and middle-aged Nigerian women.