The Lesson for Men and Women
At the time of this writing there has been a flurry of public and scientific commentary on the subject of Hormone Replacement Therapy (HRT) for menopausal and post-menopausal women.  Somewhere between 6 and 20 million women in America have been told that because of the medicine they are taking they could be at risk for heart attacks, strokes, and breast cancer.  Physicians who have prescribed these medicines for many years are hit with the realization that the new information about their routinely prescribed medicines may be leading to serious risks while accomplishing some beneficial effects such as preventing or slowing osteoporosis, reducing the symptoms of menopause such as hot flashes and mood swings, and improving skin and vaginal dryness

What Actually Happened
Medicine, as scientifically based as it is, has different degrees of scientific soundness.  The general progress in medicine is marked by roller coaster ups and downs -whether it is a medication or a surgical procedure or a new technology.  There is an understandable reason for this.  Someone has an idea - generally considered an hypothesis.  The hypothesis might be simple: women at menopause have less estrogen produced by the ovary and this leads to consequences like hot flashes at the time of menopause.  The hypothesis is then tested by the administration (replacement) of estrogen to perhaps several hundred peri-menopausal women and it is found that menopause is better tolerated by treated women than those who did not get the medicine.  Then drug companies produce lots of drugs with different ratios of estrogen and add progesterone since it decreases some of the adverse effects, and in clinical trials overseen by the FDA they all show that symptoms of menopause are reduced by hormone therapy.  They also find that bone density and osteoporosis are improved with the therapy.  In the natural course of the "science" of medicine millions of women are then given HRT and everyone is pleased - patients, doctors and the drug industry.  Next comes the first downer on the roller coaster, it is noticed by alert physicians that it seems that women on HRT may be having more clotting problems and even a higher incidence of breast cancer.  Both of these adverse outcomes are relatively rare and would never have been noted in the small trials that led to FDA approval, but when millions of patients are taking the drugs then the rare events begin to be noticed.