However, some women may still be able to get pregnant during treatment. Because the effects of chemotherapy on an unborn child are not known, it is important for a woman to talk to her doctor about birth control before treatment begins. After treatment, some women regain their ability to become pregnant, but in women over the age of 35 or 40, infertility is likely to be permanent. Hormonal Therapy Hormonal therapy can cause a number of side effects. They depend largely on the specific drug or type of treatment, and they vary from patient to patient.
Tamoxifen is the most common hormonal treatment.
This drug blocks the body's use of estrogen but does not stop estrogen production. Tamoxifen may cause hot flashes, vaginal discharge or irritation, and irregular periods. Any unusual bleeding should be reported to the doctor. Younger women taking tamoxifen may become pregnant more easily and should discuss birth control methods with their doctor. Serious side effects of tamoxifen are rare, but this drug can cause blood clots in the veins, especially in the legs.