O, The Oprah Magazine: The Women's Health Initiative [a major government study on postmenopausal women] recently made headlines about hormone replacement therapy [HRT]: Out of 10,000 women taking combined HRT—estrogen plus progestin—for a year, eight more will develop invasive breast cancer than in a similar group not taking hormones. Should we worry about this?
Norton: Eight out of 10,000 per year is quite a lot, especially when you're talking about people taking many years of treatment. All of the evidence is very clear that there's a higher incidence of breast cancer in women who take hormones—and the longer you take them, the higher the risk.
Love: We have not yet confirmed that taking estrogen alone increases breast cancer. But it's likely to do so by about one percent a year. There simply is no good justification for long-term use of HRT. The current thinking is: short-term use for those with bad menopausal symptoms that really interfere with their lives. And "short term" means three to five years.
O: But if you go off HRT, won't you be at a disadvantage when it comes to osteoporosis?
Norton: Not at all. Non-hormonal osteoporosis drugs called bisphosphonates (Fosamax, Actonel) have been observed very carefully, and there's no evident breast cancer risk. Another good drug option is the "designer estrogen" raloxifene (sold as Evista). Unlike the estrogen in HRT, raloxifene is a "selective estrogen receptor modulator," which acts like an estrogen on bone but like an antiestrogen on breasts. And women who take it have a 50 percent reduction in new breast cancer incidence compared with those not on the drug.
Love: I tend to hedge about that last point, because the only study was done on women with osteoporosis, and those women have a lower risk of breast cancer to start with. That's because they have low levels of hormones. Women with strong bones have more breast cancer.