Real-World Clinicopathological Characteristics, Metastatic Distribution, and Treatment Patterns of Triple-Negative Breast Cancer: A Single-Institution Experience from Nigeria

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype associated with poor prognosis and a disproportionate disease burden among women of African ancestry. Contemporary data describing its clinicopathologic characteristics, metastatic patterns, treatment, and factors associated with advanced presentation in sub-Saharan Africa remain limited. Methods: We conducted a retrospective cohort study of 869 women with histologically confirmed TNBC managed at a major tertiary cancer centre in Nigeria between May 2019 and December 2025. Demographic, clinicopathologic, treatment, and metastatic data were extracted from institutional electronic medical records. Advanced-stage presentation was defined as American Joint Committee on Cancer (AJCC) Stage III-IV disease, and multivariable logistic regression was performed to identify factors independently associated with advanced-stage presentation. Results: The mean age at diagnosis was 52.1 +/- 12.3 years. Most patients presented with Stage III (42.9%) or Stage IV (35.1%) disease, while only 21.9% presented with Stage I-II disease. Grade II (51.3%) and Grade III (36.5%) tumours predominated, and invasive ductal carcinoma accounted for 83.0% of cases. Among 305 patients with Stage IV disease, lung, bone, liver, and brain metastases occurred in 48.5%, 38.7%, 20.0%, and 18.4%, respectively. Overall, 73.1% underwent surgery, 83.2% received chemotherapy, and 63.5% received radiotherapy. On multivariable analysis, tumour grade was independently associated with advanced-stage presentation. Compared with Grade I tumours, Grade II tumours were associated with significantly greater odds of advanced-stage disease (adjusted odds ratio [aOR] 2.45, 95% confidence interval [CI] 1.39-4.32; p = 0.002), while Grade III tumours demonstrated more than five-fold higher odds (aOR 5.15, 95% CI 2.73-9.82; p < 0.001). Conclusion: These findings demonstrate that TNBC in this Nigerian cohort presented predominantly at advanced stages and showed a visceral, lung-predominant metastatic distribution. The independent association between higher tumour grade and advanced-stage presentation underscores the need for earlier diagnosis, appropriate staging pathways, and strengthened multidisciplinary management in resource-constrained settings. Keywords: Triple-negative breast cancer; Metastasis; Advanced-stage disease; Treatment patterns; Nigeria