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TREATMENT
16
Oestrogen plus progestogen increased risk of breast cancer in
postmenopausal women
Chlebowski RT, Hendrix SL, Langer RD, et al. Influence of estrogen plus progestin on breast cancer and mammography in healthy
postmenopausal women: the Women’s Health Initiative Randomized Trial. JAMA 2003;289:3243–53.
...............................................................................................................................
postmenopausal women, does oestrogen plus progestogen hormone therapy increase the risk of abnormal
Q Inmammographic
results and diagnosis of breast cancer?
METHODS
higher proportion of abnormal mammography results. The difference
was seen at 1 year (9.4% v 5.4%, p,0.001) and continued throughout
the study (total study period 32% v 21%, p,0.001).
Design: randomised, placebo controlled trial (Women’s Health
Initiative).
CONCLUSION
Allocation: concealed.
In postmenopausal women, oestrogen plus progestogen hormone
therapy increased cases of total and invasive breast cancer and
abnormal mammogram results.
Blinding: blinded (clinicians, participants, data collectors,
outcome assessors, and monitoring committee).
A modified version of this abstract appears in ACP Journal Club.
Follow up period: mean 5.6 years.
Setting: 40 US clinical centres.
Commentary
T
Patients: 16 608 postmenopausal women who were 50–79
years of age (mean age 63 y). Exclusion criteria: previous
hysterectomy, breast cancer, or probable survival ,3 years.
Interventions: 1 daily tablet of conjugated equine oestrogen,
0.625 mg, and medroxyprogesterone acetate, 2.5 mg (Prempro,
Wyeth Ayerst, Philadelphia, PA, USA) (n = 8506) or placebo
(n = 8102).
Outcomes: incidence of breast cancer (total, invasive, and in
situ) and abnormal mammography results.
Patient follow up: 96%.
MAIN RESULTS
Analysis was by intention to treat. Women who received oestrogen
plus progestogen had a greater incidence of total and invasive breast
cancer than did women who received placebo; in situ breast cancer
cases were not increased (table). The increase in invasive breast
cancer with oestrogen plus progestogen was seen across almost all
risk categories. Invasive breast cancers were larger in the oestrogen
plus progestogen group (mean 1.7 cm v 1.5 cm, p = 0.04) and were
diagnosed at a more advanced stage (regional or metastatic
[compared with local] 25% v 16%, p = 0.04) than in the placebo
group. Women who received oestrogen plus progestogen also had a
.............................................................
For correspondence: Dr R T Chlebowski, Harbor-UCLA Research and
Education Institute, Torrance, CA, USA. [email protected]
Sources of funding: National Heart, Lung and Blood Institute and WyethAyerst Research Laboratories.
he complex issues surrounding hormone replacement therapy have
been escalating over the past decade. Initial results of the Women’s
Health Initiative (WHI) trial released in 20021 have served to further
complicate the decisions made by prescibers and potential consumers of
hormone therapy. The WHI report by Chlebowski et al provides specific
details about breast cancer outcomes for the oestrogen plus progestogen
and placebo groups. Similar results regarding hormone therapy and
breast cancer have been reported in European studies.2 3
It was previously believed that the increased risk of breast cancer with
hormone therapy was seen in women with longer term (.5 y) use. These
recent results reveal unexpected findings of early development of invasive
breast cancers with the use of oestrogen plus progestogen. Additionally,
the use of combined hormone therapy resulted in higher rates of
mammographic abnormalities, adding to the emotional and economic
burden for both patients and providers.
Future reports of the WHI trial results will help to discern the survival
outcomes for the 2 groups and may provide insight about the use of
oestrogen alone hormone therapy. In the interim, the results of the WHI to
date provide a convincing argument against the use of oestrogen plus
progestogen. It seems the increased risk of breast cancer and
mammographic abnormalities is truly not worth the potential benefit
derived from the therapy.
Cathy R Kessenich, RN, DSN, ARNP
Department of Nursing, University of Tampa
Tampa, Florida, USA
1 Rossouw JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen
plus progestin in healthy postmenopausal women: principal results from the
Women’s Health Initiative randomized controlled trial. JAMA
2002;288:321–33.
2 Beral V; Million Women Study Collaborators. Breast cancer and hormonereplacement therapy in the Million Women Study. Lancet 2003;362:419–27.
3 Gayet A, Esteve J, Seradour B, et al. Does hormone replacement therapy
increase the frequency of breast atypical hyperplasia in postmenopausal
women? Results from the Bouches du Rhone district screening campaign.
Eur J Cancer 2003;39:1738–45.
Oestrogen plus progestogen (Oest + Prog) v placebo for postmenopausal women*
Outcomes at mean 5.6 years
Oest + Prog
Placebo
Hazard ratio (95% CI)
Cases of breast cancer (all)
Cases of invasive breast cancer
Cases of in situ breast cancer
245
199
47
185
150
37
1.24 (1.02 to 1.50)
1.24 (1.01 to 1.54)
1.18 (0.77 to 1.82)
*CI defined in glossary.
Not significant.
www.evidencebasednursing.com
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Oestrogen plus progestogen increased risk of
breast cancer in postmenopausal women
Evid Based Nurs 2004 7: 16
doi: 10.1136/ebn.7.1.16
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