Does hrt cause cancer ?

Depends on the type: It is well known that unopposed estrogen therapy can cause endometrial cancer. While some literature suggests that there is a relationship between "hrt" (ie: estrogen/progesterone) and breast cancer, there are no definitive studies confirming a cause and effect relationship. Yet, is is also known that some, but not all, breast cancers will grow faster when stimulated by estrogen.

Increases risk: Although it is hard to prove that ert "causes" breast cancer, there are many suggestive studies that show that women who take ert for a prolonged period of time have an increased risk of developing breast cancer. Most post-menopausal breast cancers are estrogen receptive and a drug (tamoxifen) that blocks estrogen clearly decreases a woman's risk.