It is frequently downregulated in various types of cancer, including lung cancer [21,55,56,57], skin cutaneous melanoma [58], pancreatic cancer [59], gastric cancer [60], breast cancer [61,62], colorectal cancer (CRC) [63], glioblastoma [64], nasopharyngeal carcinoma (NPC) [65], hepatocellular carcinoma (HCC) [66], uterine endometrial cancer [67], head and neck cancer [68,69], thyroid cancer [70,71], choriocarcinoma [19], skin cutaneous melanoma (SKCM) [58], and esophageal cancer [72], suggesting a broad tumor-suppressive activity of HOPX in carcinoma. This evidence concerns the gene HOPX and breast cancer.