Among various subtypes of breast cancer, Breast Invasive Ductal Carcinoma exhibited the highest mutation frequency of SIX1 followed by Breast Invasive Lobular Carcinoma; whereas, Breast Invasive Mixed Mucinous Carcinoma and Breast Invasive Carcinoma (NOS) demonstrated minimal mutational changes of SIX1. This evidence concerns the gene SIX1 and breast cancer.