Women who have this gene are also more likely to be harmed by radiation, including that from mammography. Because breast tissue is highly sensitive to estrogens, the longer a women is exposed to estrogen over her lifetime, the higher the risk for breast cancer. In fact, one study reported that blood tests measuring high levels of estrogen and testosterone may eventually identify older women at increased risk for breast cancer. Early Menstruation and Late Menopause. Pregnancy and Abortion.
Pregnancy plays an odd dual role in breast cancer.
It appears to increase the risk for up to 15 years following the first birth, particularly in older women, but after that women who have given birth have a lower risk than those who have not. Subsequent births do not seem to have any additional impact. The increased risk from abortion is most likely to be very small, however. A small risk for breast cancer appears to develop in women while taking oral contraceptives and for about 10 years after stopping the Pill. Hormone Replacement Therapy.