Survival pattern of rare histological types of breast cancer in a Nigerian institution

INTRODUCTION: breast cancer is the most common cancer affecting women worldwide. It is a heterogeneous disease with diverse histological types that are associated with different natural history and response to therapy. Invasive ductal and lobular carcinoma are the most common histological types. There are rare histological types with different biological behaviours from the common types, although treatment approaches are the same. Data on rare histological types of breast cancer in our population are scarce raising the need to identify these patients and document their treatment outcome. The objectives of this study are to determine the proportion and treatment outcomes of breast cancer patients with rare histological types. METHODS: this was an observational retrospective study using records of patients treated for breast cancer at the University College Hospital Ibadan Nigeria from 2008 to 2012. Patients with rare histological types were selected for further analysis. Data on patient and tumour characteristics were extracted and five-year survival pattern was determined using Kaplan Meier method. RESULTS: the total number of patients with breast cancer was 761. Thirty-two (4.2%) had rare histology that consisted of medullary carcinoma 14(1.9%), mucinous carcinoma 10(1.4%) and 2(0.3%) each for squamous cell carcinoma, stromal sarcoma, cribriform carcinoma and Paget's disease. The overall five-year survival was 50% with median survival of 52 months. CONCLUSION: the proportion of breast cancer patients with rare histology is low similar to other reports among Caucasians. Medullary adenocarcinoma was the most common subtype followed by mucinous adenocarcinoma.