Comparison of Clinicopathological Features and Survival in Triple-Negative and Non-Triple Negative Breast Cancer Patients in Tanzania.

Purpose: Breast cancer is a heterogeneous disease with a wide spectrum of subtypes, each with distinct biological features. Data on tumor subtypes in East Africa is sparse despite the rising incidence of breast cancer in this region. We aimed to determine the prevalence of triple-negative breast cancer (TNBC) and to compare clinicopathological features, overall survival (OS), and factors affecting OS of patients with TNBC and non-TNBC in Tanzania.

Patients and methods: This retrospective nested case-control study included patients with histologically proven breast cancer treated at Ocean Road Cancer Institute (ORCI) in Tanzania from January 2018 to December 2019. Logistic regression was used to determine factors associated with TNBC, and Cox proportional hazards regression was used to determine the factors independently associated with overall survival.

Results: TNBC constituted 23.3% of all breast cancer diagnoses. Patients in the TNBC group were younger (median age 46 vs 53 years p < 0.001) and more often presented with stage IV disease (12% vs 4%, p = 0.001). Three-year overall survival (OS) was significantly lower in the TNBC group (36%) compared to the non-TNBC group (57%) (p = 0.004) and remained lower for the TNBC group across every tumor stage. Brain metastasis was higher in the TNBC group (34% vs 7%, p < 0.001). Factors associated with improved survival included shorter symptom duration (0.53, (0.36-0.78), earlier stage (0.23, (0.12-0.46)), use of neoadjuvant chemotherapy (0.59 (0.40-0.86)), and surgery with clean margins (0.34 (0.19-0.60)).

Conclusions: TNBC accounted for nearly a quarter of the breast cancers at ORCI. TNBC was associated with younger age, more aggressive clinicopathologic features, and worse survival. Efforts toward earlier diagnosis and optimized therapies will be critical to improving TNBC outcomes in Tanzania.