Are hormones (menstruation) related to breast cancer?
Breast cancer is thought to be a hormone-related disease. One clue for this is the observation that women are over 100 times more likely to develop breast cancer than men (even though men also have breast tissue). Some scientists believe that it is the great hormonal difference between men and women that explains a woman’s higher risk. One hormone that has been of particular interest is estrogen, because estrogen stimulates the growth of breast cells. Beginning menstruation at an early age (before 13) or having a late menopause (after 55) are risk factors. This may be because a woman’s circulating levels of estrogen are highest during the years between menarche and menopause. The greater the number of years in which menstruation occurs, the greater will be the woman’s lifetime exposure to high levels of estrogen. Breast cancer risk is also higher for women who had their first child after the age of 30 and for those who never had children. Tall women have a slightly higher risk for prem
