The use of continuous combined hormone replacement therapy, consisting of an
oestrogen and a progestogen taken daily by postmenopausalwomen, is
increasing. Its possible benefits are the preventionof endometrial
hyperplasia and reduction in the occurrence ofendometrial bleeding
with time. Daily exposure to oestrogen andprogestin without a break
may be more important than using oestrogenintermittently in
prevention of disease. A major concern is theoccurrence of
endometrial cancer in women using cyclic or sequentialhormone
replacement with the progestin being given for eitherless than
10 days each month, 10-16 days each month, or everythree months for
14 days. 12 The
case-control studies indicatea significant increased risk in
endometrial cancer with a reductionin the number of days of exposure
to progestin. The use of continuouscombined hormone replacement
therapy not only does not increasethe incidence of endometrial
cancer but could even be protectivecompared with non-use of hormone
replacement.3
Most clinical trials of continuous combined hormone replacement therapy have
been for one year in order to obtain regulatoryapproval for the
products.4 In some instances two and threeyears of use have been reported, but these data are limited.5The end point in clinical trials is endometrial hyperplasia ratherthan endometrial cancer because of the low incidence of endometrialcancer in the general population. In clinical situations we assumethat inhibition of endometrial hyperplasia implies endometrial
protection. This assumption has been challenged recently, witha call
for randomised prospective clinical trials to documentthe efficacy
of progestins in preventing endometrial cancer.6
To date, all clinical trials of unopposed oestrogen at moderate and high
doses have shown an increase in the incidence ofendometrial
hyperplasia, which is related to dose and duration.4The same is true for endometrial cancer after use of unopposed
oestrogen. 12 The
rate of endometrial hyperplasia was nodifferent for continuous
combined hormone replacement and placeboin a Cochrane meta-analysis.4
With use of sequential hormonereplacement, the rates of endometrial
hyperplasia were no differentfrom placebo, although there was an
increase in the occurrenceof hyperplasia after 24 months (odds ratio
4, 95% confidence interval1.2 to 14.0).
Doctors are confronted with women who have taken continuous combined hormone
replacement for several years and then experienceendometrial
bleeding and spotting. Assessment of these women hasentailed
ultrasound imaging of the endometrium, hysteroscopy,and endometrial
assessment through biopsy. The accuracy of ultrasonographyin
diagnosing endometrial disease in these patients is open toquestion.7
The reason for this intensity of evaluation of thebleeding is that
doctors have been trained to evaluate aggressivelyany endometrial
bleeding in postmenopausal women. These investigationshave usually
failed to document any malignant cause of the bleedingin women
taking continuous combined hormone replacement; rather,endometrial
polyps or uterine fibroids seem to be the most commonfinding.
A paper in this issue (p 239)
addresses the issue of limited published data in long term users of continuous
combined hormonereplacement by presenting a 5 year follow up of
postmenopausalwomen taking a preparation of 2.0 mg oestradiol and
1.0 mg norethindroneacetate (Kliofem/Kliogest; Novo Nordisk,
Denmark).8 The paperfound no evidence
of endometrial hyperplasia after five yearsof continuous combined
hormone replacement therapy. Moreover,75% of the women had a final
endometrial assessment. This is noteworthybecause the usual
attrition rates in clinical trials are higherthan that in thisstudy.
These data are reassuring because they are in agreement with case-control
studies that have documented a reduction in theincidence of
endometrial cancer in women taking continuous combinedhormone
replacement therapy.1-3 These data should, however,
betaken in context with the formulation of oestrogen and progestinused in the studyoestradiol-17
and norethindrone. Other formulationsof oestrogen and progestin may
not result in the same outcome.This is a speculative statement,
based on the fact that each progestinhas a different biological
profile. On the basis of biochemicalparameters, norethindrone could
be considered a more potent progestinthan either medroxyprogesterone
acetate or progesterone.9 Todate
endometrial morphology has been used to determine the safetyof the
progestin used with oestrogen in hormone replacement preparations.
The end point in clinical trials has been the morphological changes
seen in the endometrial tissue acquired through biopsy. The accuracy
of the interpretation of the histology of the endometrium between
pathologists has been questioned because of the discrepanciesfound
in the interpretation of the endometrium in clinical trials.10
Better markers of endometrial stimulation and inhibition than that of
histology alone are needed. Until these are available,we must rely
on the pathological interpretation of the findings,as was done in
this study, to reassure us that the endometriumis protected with
continuous combined hormone replacement therapy.For clinicians this
means that investigation of a woman takingcontinuous combined
hormone replacement without bleeding is notrequired, and with
bleeding and spotting the chances of findinga neoplasm are low to
non-existent.
David F Archer, director, clinical research centre
and professor of obstetrics and gynaecology.
The Jones Institute for Reproductive Medicine 601 Colley Avenue, Norfolk, VA
23507 USA (archerdf@evms.edu)
Footnotes
David F Archer has received research grants support from Wyeth, Organon,
Ortho, Schering-Plough, Solvay, TAP Pharmaceuticals,Novo Nordisk,
and Besins for several clinical trials includingmany related to
menopause. He is or has been a consultant to Wyeth,Organon, Novo
Nordisk, Solvay, Schering-Plough, TAP, and Watsonlaboratories. He
has received support as a speaker from Wyeth,Ortho, Organon, Novo
Nordisk, andSolvay.
Beresford SA, Weiss NS, Voigt LF, McKnight B. Risk of
endometrial cancer in relation to use of oestrogen combined with cyclic
progestagen therapy in postmenopausal women. Lancet 1997; 349:
458-461[Medline].
Weiderpass E, Baron JA, Adami HO, Magnusson C, Lindgren A,
Bergstrom R, et al. Risk of endometrial cancer following estrogen
replacement with and without progestins. J Natl Cancer Inst 1999; 91:
1131-1137[Abstract/Full
Text].
Hill DA, Weiss NS, Beresford SA, Voigt LF, Daling JR,
Stanford JL, et al. Continuous combined hormone replacement therapy and risk
of endometrial cancer. Am J Obstet Gynecol 2000; 183: 1456-1461[Medline].
Lethaby A, Farquhar C, Sarkis A, Roberts H, Jepson R,
Barlow D. Hormone replacement therapy in postmenopausal women: endometrial
hyperplasia and irregular bleeding. Cochrane Database Syst Rev
2000;2:CD000402.
Writing Group for the PEPI Trial. Effects of hormone
replacement therapy on endometrial histology in postmenopausal women. The
postmenopausal estrogen/progestin interventions (PEPI) trial. JAMA
1996; 275: 370-375[Medline].
Langer RD, Pierce JJ, O'Hanlan KA, Johnson SR, Espeland MA,
Trabal JF, et al. Transvaginal ultrasonography compared with endometrial
biopsy for the detection of endometrial disease. Postmenopausal
estrogen/progestin interventions trial. N Engl J Med 1997; 337:
1792-1798[Abstract/Full
Text].
Wells M, Sturdee DW, Barlow DH, Ulrich LG, O'Brien K,
Campbell MJ, et al. Effect on endometrium of long term treatment with
continuous combined oestrogen-progestogen replacement therapy: follow up
study. BMJ 2002; 324: 239-242[Full
Text].
Whitehead MI, Townsend PT, Pryse-Davies J, Ryder TA, King
RJ. Effects of estrogens and progestins on the biochemistry and morphology
of the postmenopausal endometrium. N Engl J Med 1981; 305: 1599-1605[Abstract].
Pickar JH, Yeh I, Wheeler JE, Cunnane MF, Speroff L.
Endometrial effects of lower doses of conjugated equine estrogens and
medroxyprogesterone acetate. Fertil Steril 2001; 76: 25-31[Medline].
PAPERS Effect on endometrium of long term treatment with continuous combined
oestrogen-progestogen replacement therapy: follow up study.
Michael Wells, David W Sturdee, David H Barlow, Lian G Ulrich, Karen
O'Brien, Michael J Campbell, Martin P Vessey, and Anthony J Bragg
BMJ 2002 325: 239. [Abstract][Abridged text][Full text]
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