Prolactin is a natural hormone in the body that plays a role in breast growth and the production of milk during breastfeeding. It is mainly produced in the pituitary gland (a small gland near the brain). Researchers can study prolactin by measuring levels of prolactin in the blood.
Women with higher blood levels of prolactin may have a higher risk of breast cancer than women with lower levels [201-202]. Measures of blood levels of prolactin may one day help estimate breast cancer risk.