By GARY TAUBES
Once upon a time, women took estrogen only to
relieve the hot flashes, sweating, vaginal dryness and the other discomforting
symptoms of menopause. In
the late 1960s, thanks in part to the efforts of Robert Wilson, a Brooklyn
gynecologist, and his 1966 best seller, “Feminine Forever,” this began to
change, and estrogen therapy evolved into a long-term remedy for the chronic
ills of aging. Menopause, Wilson argued, was not a natural age-related
condition; it was an illness, akin to diabetes or
kidney failure, and one that could be treated by taking estrogen to replace the
hormones that a woman’s ovaries secreted in ever diminishing amounts. With this
argument estrogen evolved into hormone-replacement therapy, or H.R.T., as it
came to be called, and became one of the most popular prescription drug
treatments in America.
By the mid-1990s, the American Heart
Association, the American College of Physicians and the American College of
Obstetricians and Gynecologists had all concluded that the beneficial effects
of H.R.T. were sufficiently well established that it could be recommended to
older women as a means of warding off heart disease and osteoporosis.
By 2001, 15 million women were filling H.R.T. prescriptions annually; perhaps 5
million were older women, taking the drug solely with the expectation that it
would allow them to lead a longer and healthier life. A year later, the tide
would turn. In the summer of 2002, estrogen therapy was exposed as a hazard to
health rather than a benefit, and its story became what Jerry Avorn, a Harvard epidemiologist, has
called the “estrogen debacle” and a “case study waiting to be written” on the
elusive search for truth in medicine.
Many explanations have been offered to make sense of the
here-today-gone-tomorrow nature of medical wisdom — what we are advised with
confidence one year is reversed the next — but the simplest one is that it is
the natural rhythm of science. An observation leads to a hypothesis. The
hypothesis (last year’s advice) is tested, and it fails this year’s test, which
is always the most likely outcome in any scientific endeavor. There are, after
all, an infinite number of wrong hypotheses for every right one, and so the
odds are always against any particular hypothesis being true, no matter how
obvious or vitally important it might seem.
In the case of H.R.T., as with most issues of diet,
lifestyle and disease, the hypotheses begin their transformation into
public-health recommendations only after they’ve received the requisite support
from a field of research known as epidemiology. This science evolved over the
last 250 years to make sense of epidemics — hence the name — and infectious diseases.
Since the 1950s, it has been used to identify, or at least to try to identify,
the causes of the common chronic diseases that befall us, particularly heart
disease and cancer. In the
process, the perception of what epidemiologic research can legitimately
accomplish — by the public, the press and perhaps by many epidemiologists
themselves — may have run far ahead of the reality. The case of
hormone-replacement therapy for post-menopausal women is just one of the
cautionary tales in the annals of epidemiology. It’s a particularly glaring
example of the difficulties of trying to establish reliable knowledge in any
scientific field with research tools that themselves may be unreliable.
What was considered true about estrogen therapy in the 1960s and is still
the case today is that it is an effective treatment for menopausal symptoms.
Take H.R.T. for a few menopausal years and it’s extremely unlikely that any
harm will come from it. The uncertainty involves the lifelong risks and
benefits should a woman choose to continue taking H.R.T. long past menopause.
In 1985, the Nurses’ Health Study run out of the Harvard Medical School and the
Harvard School of Public Health reported that women taking estrogen had only a
third as many heart attacks as women who had never taken the drug. This
appeared to confirm the belief that women were protected from heart attacks
until they passed through menopause and that it was estrogen that bestowed that
protection, and this became the basis of the therapeutic wisdom for the next 17
years.
Faith in the protective powers of estrogen began to erode in 1998, when a
clinical trial called HERS, for Heart and Estrogen-progestin Replacement Study,
concluded that estrogen therapy increased, rather than decreased, the
likelihood that women who already had heart disease would suffer a heart
attack. It evaporated entirely in July 2002, when a second trial, the Women’s
Health Initiative, or W.H.I., concluded that H.R.T. constituted a potential
health risk for all postmenopausal women. While it might protect them against
osteoporosis and perhaps colorectal cancer, these benefits would be outweighed
by increased risks of heart disease, stroke, blood clots, breast cancer and
perhaps even dementia. And that was the final word. Or at least it was until
the June 21 issue of The New England Journal
of Medicine. Now the idea is that hormone-replacement therapy may indeed
protect women against heart disease if they begin taking it during menopause,
but it is still decidedly deleterious for those women who begin later in life.
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