There are two main types of HRT:
combination HRT contains the hormones estrogen and progesterone
estrogen-only HRT contains only estrogen
Each type of HRT seems to have a different effect on breast cancer risk.
Combination HRT increases breast cancer risk by about 75%, even when used for only a short time. Combination HRT also increases the likelihood that cancer may be found at a more advanced stage, as well as increasing the risk that a woman diagnosed with breast cancer will die from the disease.
Women who are older than 30 when they give birth to their first child have a higher risk of breast cancer than women who have never given birth (15). Recent childbirth. Women who have recently given birth have a short-term increase in breast cancer risk that declines after about 10 years. During pregnancy and lactation, the levels of estrogen and prolactin are increased, and some studies demonstrate that high levels of estrogen and prolactin are associated with the development of breast cancer.