Pathological characteristics of triple negative breast cancer phenotype in a cohort of Sri Lankan females

Breast cancer is the commonest cancer among Sri Lankan women. Triple negative is a type of breast cancer that is negative for expression of oestrogen receptors (ER), progesterone receptors (PR) and human epidermal growth factor 2 receptors (HER 2). Objective: To identify the pathological characteristics of triple negative breast cancer phenotype in a group of Sri Lankan women. Method: 200 cases of diagnosed breast cancers were analysed to determine the prevalence of triple negative breast cancers. All the slides were re-examined histologically to find out whether there were specific morphological features in the triple negative group when compared with the ER/PR positive HER 2 negative group, ER/PR negative HER2 positive group and ER/PR positive HER2 positive group. Results and conclusion: The prevalence of triple negative breast cancer in the study group was 36%. The mean age affected by this tumour category was 49.5 years. The commonest age group affected was 41-50 years. The commonest histological type in all categories was invasive ductal carcinoma. A significant number of triple negative tumours were histologically Grade 3 compared to the ER/PR positive HER2 negative group. The mean tumour size was 2.73 cm. Although the percentage of triple negative tumours among the lymph node stages was similar, a statistically significant number of triple negative tumours was in stage 3 and showed tumour necrosis. The triple negativity was also associated with a lymphocytic reaction at the host tumour interface and infiltrative margins. Triple negative status showed a negative association with skin and nipple invasion, lymphovascular invasion and an in-situ component.