It has been reported that ALDH1A1 expression could be a predictor of poor prognosis in a wide range of cancers such as ovarian carcinoma [6], lung cancer [7], breast cancer [8, 9], esophageal squamous cell carcinoma [10], prostate cancer [11], papillary thyroid carcinoma [12], colorectal carcinoma [13, 14] and gastric cancer [15]. Here, ALDH1A1 is linked to breast cancer.