Treatment patterns and outcome of her2-positive breast cancer patients in Tanzania

Abstract

ABSTRACT Background: Breast cancer is the second leading cause of death among women globally, with an approximately 20% rate of the HER2-positive (HER2+) subtype. This subtype is linked to poorer outcomes and higher mortality rates. Despite trastuzumab being the preferred treatment, many patients, especially in developing countries like Tanzania, are unable to access it due to financial constraints. Therefore, there is a need for local data on the survival outcomes and treatment patterns of HER2-positive breast cancer patients in resource-limited settings to guide optimal management strategies. Objective: to assess the treatment and survival outcomes of Tanzanian patients diagnosed with HER2—-positive (HER2+) breast cancer at Ocean Road Cancer Institute (ORCI) and Muhimbili National Hospital (MNH). Materials and Methods: This hospital-based retrospective study was conducted at ORCI and MNH from January 2018 to May 2021 by enrolling patients with HER2+ non-metastatic breast cancer. The dependent variable was a three-year overall survival rate. The independent variables were social demographics and clinic pathological characteristics such as hypertension, diabetes mellitus, histology, HIV, ER/PR status, stage at diagnosis, laterality, ECOG, age, marital status, occupation, menopause status, parity, education level, smoking, alcohol, and payment mode and treatment pattern. Survival analysis was done by using the Kaplan-Meier method. Cox regression analysis was used in the multivariate analysis. Results: In this study, 169 patients with HER2-positive breast cancer had a median age of 50. The majority had ductal carcinoma (92.3%), were estrogen receptor-positive (50.3%), and had stage III cancer (58.6%). Approximately 70.4% of the patients received Trastuzumab, 24.3% had neoadjuvant chemotherapy, and 95.9% underwent surgical treatment. Trastuzumab was commonly used in the adjuvant setting compared to the neoadjuvant setting and was more accessible to patients with higher socioeconomic status. The 3-year overall survival rate was 57%, with a median survival time of 72 months. Trastuzumab was associated with a 74% lower risk of mortality. Extended therapy with Trastuzumab was more beneficial in hormone negative HER2+ breast cancer compared to hormonal receptor-positive. Advanced-stage disease increased the likelihood of death, while not smoking and premenopausal status were linked to lower mortality. An ECOG score of more than one was associated with a higher mortality risk. Conclusion: The study found that trastuzumab improved overall patient outcomes in breast cancer care. Extended trastuzumab therapy was associated with better survival rates, particularly in hormone receptor-negative HER2+ patients. The study also highlighted the significant role of socioeconomic factors in treatment accessibility and outcomes, including the impact of health insurance on survival rates. It also showed the association between a higher mortality rate and advanced cancer stage, ECOG, smoking, and menopausal status. Keywords: HER2-positive, breast cancer, trastuzumab, treatment outcome, treatment pattern