A number of studies have looked at women who have had an early menopause as a result of having their ovaries surgically removed. These have shown that early menopause reduces a woman's risk of breast cancer. The earlier menopause occurs the greater the reduction in risk but by the age of 50 the level of risk is the same as for other women.

Although the studies all agree that early menopause reduces the risk of breast cancer before the age of 50 years it is not clear how great the reduction is. It is important to remember that the younger a woman is, the less likely she is to develop breast cancer, whether she has her ovaries or not.