Regarding breast cancer, CEACAM1 has been shown to be down-regulated compared to normal breast tissue (Yang et al., 2015), similar to its expression in prostate (Busch et al., 2002; Liu J. et al., 2020), endometrial (Bamberger et al., 1998), gastric (Takeuchi et al., 2019) and colon cancer (Fournes et al., 2001; Song et al., 2011), identifying it as a tumor suppressor. This evidence concerns the gene CEACAM1 and breast cancer.