ESR1 and breast cancer: At least 1 mutation was detected in all 39 genes represented on the panel (range 1–73) with the most frequently altered genes being TP53 (36.0% of patients), PIK3CA (32.7%), MAP3K1 (27.7%), CDH1 (24.5%), PTEN (17.6%), and ESR1 (16.4%), closely resembling that of other studies that have undertaken genomic profiling of breast cancer [19–22].