Findings of women's health initiative trial need not alarm
users
Observational studies have suggested a major health benefit of postmenopausal
hormone replacement therapy, including reductionsin coronary heart
disease, osteoporotic fractures, and colorectalcancer. Such studies
have also suggested an increased risk forbreast cancer and possibly
stroke. Critics have said that thebenefits, but not the risks, may
simply reflect a healthy userbias and have demanded randomised
trials. The women's health initiativeis a randomised trial of these
health outcomes to assess risksand benefits of intervention
strategies in a postmenopausal population.The trial has shown harm
for cardiovascular diseases, includingcoronary heart disease (the
primary outcome) and stroke, althoughit showed benefits for hip
fractures and bowel cancer. The relativerisks for invasive breast
cancer, coronary heart disease, andstroke were increased, although
the absolute risks were very small.The findings may not be the same
for types of hormone replacementtherapy other than those used in
this trial, or for lower dosesof the regimen that was useda
point that is acknowledged by theauthors of thestudy.
One treatment arm of the trial included over 16 000 postmenopausal women who
were taking continuous combined oestrogen-progestogenhormone
replacement therapy, using conjugated equine oestrogens0.625 mg plus
medroxyprogesterone acetate 2.5 mg daily, testedagainst placebo.1
This primary prevention study was due torun for 8.5 years but was
halted at just over 5 years becausethe number of cases of breast
cancer had reached a prespecifiedsafety limit. For 10 000 women
taking hormone replacement therapyeach year, compared with those not
taking it, there would be anadditional eight cases of invasive
breast cancer, seven heartattacks, eight strokes, and eight
pulmonary embolisms. However,there would also be six fewer bowel
cancers and five fewer hipfractures. Overall mortality was not
increased withtherapy.
Survival of the human species over two million years implies that female sex
hormones by themselves are not dangerous to health.If harm is
established, we must therefore examine the types ofsubstitutes that
we use and their means of delivery. The smallincrease in the number
of patients with breast cancer accordswith previous population
studies,2 as are the increases invenous
thromboembolism and the decreases in fractures and in bowelcancer.
Given the biological effects of oestrogen on the cardiovascular
system, the lack of benefit on coronary heart disease is surprisingbutthese findings apply only to this particular hormone replacementtherapy regimen, and other coronary heart disease studies of thishormone replacement therapy have not shown benefit.3-5
Hormone replacement therapy regimens using different oestrogens and
progestogens, and different routes of administration,may be similar
in their effects on the breast, bowel, and skeleton.But the
metabolic effects of different regimens are clearly different,6and this is most likely to have an impact on their cardiovasculareffects. Indeed, the women's health initiative trial also has
an oestrogen-alone arm for women with hysterectomies, which hasnot
been stopped. We need to see these findings to know whetherthe
medroxyprogesterone acetate is causing the harm. It is mostunhelpful
that this point about different oestrogens and progestogenswas not
appreciated by the recent recommendations of the Committeefor Safety
of Medicines and the Medicines Control Agency,7which were inappropriate with respect to cardiovascular disease.Particularly for coronary heart disease, the dose (and possibly
type) of oestrogen and the type of progestogen may be crucial.
Similar studies using different types of hormone replacement therapy
than the one used in this trial must be carriedout.
Women who are currently taking continuous combined oestrogen-progestogen
should not panic, as it is most unlikely to havecaused considerable
harm. Certainly the risk of breast canceris not appreciably
increased during the first four years, so womenwishing to take this
therapy for the short term relief of menopausalsymptoms should be
reassured. However, they need to discuss withtheir doctor whether
they should shift to a different preparation,which could
theoretically have a more beneficial effect on thecardiovascularsystem.
There is no right or wrong hormone replacement therapy to use in the short
term, but in the light of the findings of thistrial the use of
hormone replacement therapy regimens containingconjugated oestrogens
0.625 mg together with medroxyprogesteroneacetate (at any dose)
should be avoided in the long term. Thefindings of this trial may
not apply to lower doses of conjugatedequine oestrogens, given with
or without other progestogens. Thelong term effects of alternative
hormone replacement therapy preparationshave not yet been tested in
large randomised trials, and thismust become a research
priority.
At present, long term hormone replacement therapy should be given only on an
individual basis, depending on the needs andrisk factors of the
patient. Long term therapy could still beconsidered for prevention
of osteoporosis, used as part of themanagement of women with
particular cardiovascular risk factors,and used for better quality
of life. We do not yet know the effects,if any, for the prevention
of dementia, although preliminary evidenceis encouraging. Women who
are already taking long term hormonereplacement therapy should be
reviewed and counselled. If theyneed further treatment,
consideration should be given to switchingthem to another form of
hormone replacement therapy if they aretaking a regimen of
conjugated equine oestrogen and medroxyprogesteroneacetate.
For women starting hormone replacement therapy, we continue to recommend that
the starting dose of oestrogen is kept low inwomen over the age of
60. For example, this would be 1 mg fororal, or 50 µg for
transdermal, oestradiol 17the
0.3 mg doseof conjugated equine oestrogens is not currently
available inthe United Kingdom. The risks and benefits of
alternatives tohormone replacement therapy (such as tibolone and
raloxifene)are still to be determined, but they are unlikely to be
the sameas the regimen used in the women's health initiativetrial.
John C Stevenson, reader in metabolic medicine.
j.stevenson@ic.ac.uk, Endocrinology
and Metabolic Medicine, Faculty of Medicine, Imperial College, London W2 1NY
JCS and MIW have been investigators in various clinical trials of hormone
replacement therapy regimens. JCS is an investigatorin the MRC
women's hormones intervention secondary prevention(WHISP) trial. MIW
is an investigator in the UK national trialof use of hormone
replacement therapy in women with early breastcancer. They have
attended meetings and lectured on hormone replacementtherapy,
sometimes with the support of various pharmaceuticalcompanies.
Writing group for the Women's Health Initiative
Investigators. Risks and benefits of estrogen plus progestin in healthy
postmenopausal women. JAMA 2002; 288: 321-333.
Collaborative Group on Hormonal Factors in Breast Cancer.
Breast cancer and hormone replacement therapy: collaborative re-analysis of
data from 51 epidemiological studies of 52 705 women with breast cancer and
108 411 women without breast cancer. Lancet 1997; 350: 1047-1059[Medline].
Hulley S, Grady D, Bush T, Furberg C, Herrington D, Riggs
B, et al. Randomized trial of estrogen plus progestin for secondary
prevention of coronary heart disease in postmenopausal women. JAMA
1998; 280: 605-613[Medline].
Herrington DM, Reboussin DM, Brosnihan KB, Sharp PC,
Shumaker SA, Snyder TE, et al. Effects of estrogen replacement on the
progression of coronary-artery atherosclerosis. N Engl J Med 2000;
343: 522-529[Abstract/Full
Text].
Schulman SP, Thiemann DR, Ouyang P, Chandra NC, Schulman
DS, Reis SE, et al. Effects of acute hormone therapy on recurrent ischemia
in postmenopausal women with unstable angina. J Am Coll Cardiol 2002;
39: 231-237[Medline].
Medicines Control Agency, Committee on Safety of Medicines.
New product information for hormone replacement therapy. Curr Problems
Pharmacovigilance 2002; 28: 1-2.
ALL INFORMATION, DATA, AND
MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION
PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS
OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR
LEGAL ADVICE. THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND
COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH
YOUR HEALTH CARE PROVIDER.
"A foolish faith in authority is the worst enemy of truth."
-- Albert Einstein, letter to a friend, 1901
"I know of no safe depository of the ultimate powers of the society but the people themselves, and if we think them not enlightened enough to exercise control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."
-- Thomas Jefferson, letter to William C. Jarvis, September 28, 1820
"What's the point of vaccination if it doesn't protect you from the unvaccinated?"
-- Sandy Gottstein
"Who gets to decide what the greater good is and how many will be sacrificed to it?"