Survival outcomes and prognostic factors affecting survival in patients with metastatic breast cancer

Introduction: There is an increase in breast cancer in Africa with up to 77% of patients diagnosed with advanced disease. Late diagnosis, aggressive tumor biology and inadequate or incomplete treatments contribute to high mortality rates. However, there is little data on survival outcomes and prognostic factors affecting survival in patients with metastatic breast cancer (MBC) in Africa. The study objective was to establish the survival of patients with MBC at a single tertiary health facility and to outline the clinical and pathological characteristic of the patients and their relation to survival outcomes. Methods: This was a retrospective descriptive study conducted at Aga Khan University Hospital, Nairobi of patients diagnosed with MBC between 2009 and 2017. Survival data was collected on progression free survival, survival time between diagnosis of first metastasis and death and overall survival. Information on patient’s age, menopausal status and stage at diagnosis, tumor grade, receptor status, site of metastasis and treatment given was also collected. The Kaplan-Meier Estimator was used to estimate survival. Prognostic factors for survival outcomes were analyzed using univariate analysis. Standard descriptive statistics were used to describe patient characteristics. Results: There were 131 patient diagnosed with MBC from 2009 to 2017 included in the study. Mean and median age at first diagnosis of BC were 47.01 and 47.00 years respectively with a range from 21-79 years. The median survival was 22 months. The 3-year and 5-year survival were 31.3% and 10.7% respectively. Median follow up period was 35 months. Factors significantly affecting the overall survival were Luminal A molecular subtype (HR 0.652 95% CI 0.473-0.899) and metastasis to the liver or brain (HR 0.615 95% CI 0.413-0.915 and HR 0.566 95% CI 0.330-0.973 respectively). Age at diagnosis, menopausal status, time to metastasis, grade of the tumor and the type of chemotherapy given did not show any statistically significant effect on survival after diagnosis of MBC. Conclusion: Our study found survival rates for patients diagnosed with MBC to be lower compared to studies from other Western countries but higher than in studies from Sub Saharan Africa. Luminal A molecular subtype was found to be a positive prognostic factor and metastasis to the liver or brain were found to be negative prognostic factors