I have a family history of heart disease and breast cancer. What are your views of taking estrogen and tamoxifen? Would they be as effective taken together?
You raise a very complicated question. Although there is a fair amount of evidence regarding the benefits of estrogen in preventing heart disease in postmenopausal women, and tamoxifen has been shown in some studies to reduce breast cancer risk, dealing with the two risks together in the same woman raises complicated questions.
Unfortunately you don’t tell us enough about your family history to allow me to really evaluate your risk. As far as breast cancer is concerned, cancers arising in families in which the women are at higher risk than average account for only between 5 to 10 percent of all breast cancers. That means 90 to 95 percent of breast cancers arise in women who have no known family risk. Family risk is believed to be greatest if more than one first degree relative (mother or sisters) had breast cancer before age 50. Breast cancer in a grandmother, or two aunts, would not place a woman at increased risk. Nonetheless, a family history of breast cancer is one of the largest risk factors, along with advanced age, for the development of this cancer. I mention advanced age because 75 percent of breast cancers occur in women older than 50.
Other risk factors are drinking alcohol, prolonged use of estrogen after menopause, women who first start getting their periods when they are younger than average, not having children, and late age of menopause. Radiation which has involved the breasts is also a risk factor.
Exposure to pesticides and a high fat diet have not been shown to be risk factors. A low fat diet during adolescence is still possibly a preventive measure for the disease, and girls who are athletically active during adolescence are also somewhat protected. Both of these may exert changes on the developing breasts of adolescent girls in ways that reduce their risk.
Risk factors for heart disease include: family history, smoking, hypertension, diabetes, high cholesterol and an inactive lifestyle. All of these except family history can be modified.
Taking estrogen after menopause reduces a woman’s risk of heart disease substantially, although there have been two recent studies in women who had already had one heart attack that make me less confident about the benefit of estrogen as I was.
You seem to be proposing that you take estrogen for its benefit against heart disease (and osteoporosis, hot flashes, vaginal dryness, etc.) and perhaps at the same time tamoxifen, an antiestrogen in the breast, for its protective effect against breast cancer. I would not advise using this combination. Although tamoxifen has reduced the incidence of breast cancer by 48 percent in a large study of high-risk women, there is no way to say if it would reduce risk in someone also taking estrogen. Both drugs increase the risk of developing uterine cancer, obviously a bad side effect, and although that could be countered by taking progesterone, the addition of this hormone has been thought to increase the risk of breast cancer.
I would suggest that you discuss with your doctor the possibility of taking a newer relative of tamoxifen called raloxifene, by itself. Raloxifene is an antiestrogen in the breast, and although the studies are not yet complete, it probably reduces breast cancer risk as does tamoxifen. It is also an antiestrogen in the uterus, unlike tamoxifen, and therefore carries little or no risk of uterine cancer. It acts like estrogen in the bones, so it will help prevent osteoporosis and it also seems to mimic the effect of estrogen in preventing heart disease. Tamoxifen does neither of these.
Raloxifene will not, however, prevent hot flashes as does estrogen, and probably will not prevent vaginal drying. Raloxifene, therefore, appears to offer the breast protection of tamoxifen and the heart and bone protection of estrogen, without the risk of uterine cancer. It does cause increased blood clotting in some women, but this is also a risk with estrogen and tamoxifen.