See BOXED
WARNINGS.
The use of unopposed estrogens in women who have a uterus is associated with
an increased risk of endometrial cancer.
1.
Cardiovascular disordersEstrogen and estrogen/progestin therapy has been associated with
an increased risk of cardiovascular events such as myocardial infarction and
stroke, as well as venous thrombosis and pulmonary embolism (venous
thromboembolism or VTE). Should any of these occur or be suspected, estrogens
should be discontinued immediately.
Risk factors for arterial vascular disease (e.g., hypertension, diabetes
mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous
thromboembolism (e.g., personal history or family history of VTE, obesity, and
systemic lupus erythematosus) should be managed appropriately.
a. Coronary heart disease and stroke
In the Women’s Health Initiative study (WHI), an increase in the
number of myocardial infarctions and strokes has been observed in women
receiving CE compared to placebo. These observations are preliminary. (See CLINICAL PHARMACACOGY, Clinical Studies.)
In the CE/MPA substudy of WHI, an increased risk of coronary heart disease
(CHD) events (defined as nonfatal myocardial infarction and CHD death) was
observed in women receiving CE/MPA compared to women receiving placebo (37 vs 30
per 10,000 women-years). The increase in risk was observed in year one and
persisted.
In the same substudy of WHI, an increased risk of stroke was observed in
women receiving CE/MPA compared to women receiving placebo (29 vs 21 per 10,000
women-years). The increase in risk was observed after the first year and
persisted.
In postmenopausal women with documented heart disease (n = 2,763, average age
66.7 years) a controlled clinical trial of secondary prevention of
cardiovascular disease (Heart and Estrogen/Progestin Replacement study; HERS)
treatment with CE/MPA (0.625mg/2.5mg per day) demonstrated no cardiovascular
benefit. During an average follow-up of 4.1 years, treatment with CE/MPA did not
reduce the overall rate of CHD events in postmenopausal women with established
coronary heart disease. There were more CHD events in the CE/MPAtreated group
than in the placebo group in year 1, but not during the subsequent years. Two
thousand three hundred and twenty-one women from the original HERS trial agreed
to participate in an open label extension of HERS, HERS II. Average follow-up in
HERS II was an additional 2.7 years, for a total of 6.8 years overall. Rates of
CHD events were comparable among women in the CE/MPA group and the placebo group
in HERS, HERS II and overall.
Large doses of estrogen (5 mg conjugated estrogens per day), comparable to
those used to treat cancer of the prostate and breast, have been shown in a
large prospective clinical trial in men to increase the risks of nonfatal
myocardial infarction, pulmonary embolism, and thrombophlebitis.
b. Venous thromboembolism (VTE)
In the Women’s Health Initiative study (WHI), an increase in VTE
has been observed in women receiving CE compared to placebo. These observations
are preliminary. (See CLINICAL
PHARMACOLOGY, Clinical Studies.)
In the CE/MPA substudy of WHI, a 2-fold greater rate of VTE, including deep
venous thrombosis and pulmonary embolism, was observed in women receiving CE/MPA
compared to women receiving placebo. The rate of VTE was 34 per 10,000
women-years in the CE/MPA group compared to 16 per 10,000 women-years in the
placebo group. The increase in VTE risk was observed during the first year and
persisted.
If feasible, estrogens should be discontinued at least 4 to 6 weeks before
surgery of the type associated with an increased risk of thromboembolism, or
during periods of prolonged immobilization.
2.
Malignant neoplasmsa.
Endometrial cancerThe use of unopposed estrogens in women with intact uteri has
been associated with an increased risk of endometrial cancer. The reported
endometrial cancer risk among unopposed estrogen users is about 2- to 12-fold
greater than in non-users, and appears dependent on duration of treatment and on
estrogen dose. Most studies show no significant increased risk associated with
use of estrogens for less than one year. The greatest risk appears associated
with prolonged use, with increased risks of 15- to 24-fold for five to ten years
or more and this risk has been shown to persist for at least 8 to 15 years after
estrogen therapy is discontinued.
Clinical surveillance of all women taking estrogen/progestin combinations is
important. Adequate diagnostic measures, including endometrial sampling when
indicated, should be undertaken to rule out malignancy in all cases of
undiagnosed persistent or recurring abnormal vaginal bleeding. There is no
evidence that the use of natural estrogens results in a different endometrial
risk profile than synthetic estrogens, of equivalent estrogen dose. Adding a
progestin to estrogen therapy has been shown to reduce the risk of endometrial
hyperplasia, which may be a precursor to endometrial cancer.
b. Breast cancer
The use of estrogens and progestins by postmenopausal women has
been reported to increase the risk of breast cancer. The most important
randomized clinical trial providing information about this issue is the Women’s
Health Initiative (WHI) substudy of CE/MPA (see CLINICAL PHARMACOLOGY, Clinical Studies). The results from observational
studies are generally consistent with those of the WHI clinical trial and report
no significant variation in the risk of breast cancer among different estrogens
or progestins, doses, or routes of administration.
The CE/MPA substudy of WHI reported an increased risk of breast cancer in
women who took CE/MPA for a mean follow- up of 5.6 years. Observational studies
have also reported an increased risk for estrogen/progestin combination therapy,
and a smaller increased risk for estrogen alone therapy, after several years of
use. In the WHI trial and from observational studies, the excess risk increased
with duration of use. From observational studies, the risk appeared to return to
baseline in about five years after stopping treatment. In addition,
observational studies suggest that the risk of breast cancer was greater, and
became apparent earlier, with estrogen/progestin combination therapy as compared
to estrogen alone therapy.
In the CE/MPA substudy, 26% of the women reported prior use of estrogen alone
and/or estrogen/progestin combination hormone therapy. After a mean follow-up of
5.6 years during the clinical trial, the overall relative risk of invasive
breast cancer was 1.24 (95% confidence interval 1.01 – 1.54), and the overall
absolute risk was 41 vs 33 cases per 10,000 women-years, for CE/MPA compared
with placebo. Among women who reported prior use of hormone therapy, the
relative risk of invasive breast cancer was 1.86, and the absolute risk was 46
vs 25 cases per 10,000 women-years, for CE/MPA compared with placebo. Among
women who reported no prior use of hormone therapy, the relative risk of
invasive breast cancer was 1.09, and the absolute risk was 40 vs 36 cases per
10,000 women-years for CE/MPA compared with placebo. In the same substudy,
invasive breast cancers were larger and diagnosed at a more advanced stage in
the CE/MPA group compared with the placebo group. Metastatic disease was rare
with no apparent difference between the two groups. Other prognostic factors
such as histologic subtype, grade and hormone receptor status did not differ
between the groups.
The use of estrogen plus progestin has been reported to result in an increase
in abnormal mammograms requiring further evaluation. All women should receive
yearly breast examinations by a healthcare provider and perform monthly breast
self-examinations. In addition, mammography examinations should be scheduled
based on patient age, risk factors, and prior mammogram results.
3.
DementiaIn the Women’s Health Initiative Memory Study (WHIMS), 4,532
generally healthy postmenopausal women 65 years of age and older were studied,
of whom 35% were 70 to 74 years of age and 18% were 75 or older. After an
average follow-up of 4 years, 40 women being treated with CE/MPA (1.8%, n =
2,229) and 21 women in the placebo group (0.9%, n = 2,303) received diagnoses of
probable dementia. The relative risk for CE/MPA versus placebo was 2.05 (95%
confidence interval 1.21 – 3.48), and was similar for women with and without
histories of menopausal hormone use before WHIMS. The absolute risk of probable
dementia for CE/MPA versus placebo was 45 versus 22 cases per 10,000
women-years, and the absolute excess risk for CE/MPA was 23 cases per 10,000
women-years. It is unknown whether these findings apply to younger
postmenopausal women. (See CLINICAL
PHARMACOLOGY, Clinical Studies and PRECAUTIONS, Geriatric Use.)
It is unknown whether these findings apply to estrogen alone therapy.
4. Gallbladder disease
A 2- to 4-fold increase in the risk of gallbladder disease
requiring surgery in postmenopausal women receiving estrogens has been
reported.
5. Hypercalcemia
Estrogen administration may lead to severe hypercalcemia in
patients with breast cancer and bone metastases. If hypercalcemia occurs, use of
the drug should be stopped and appropriate measures taken to reduce the serum
calcium level.
6. Visual abnormalities
Retinal vascular thrombosis has been reported in patients
receiving estrogens. Discontinue medication pending examination if there is a
sudden partial or complete loss of vision, or a sudden onset of proptosis,
diplopia, or migraine. If examination reveals papilledema or retinal vascular
lesions, estrogens should be permanently discontinued.
7. Hepatic adenoma
Benign hepatic adenomas appear to be associated with the use of
oral contraceptives. Although benign, and rare, these may rupture and may cause
death through intra-abdominal hemorrhage. Such lesions have not yet been
reported in association with other estrogen or progestagen preparations but
should be considered in estrogen users having abdominal pain and tenderness,
abdominal mass, or hypovolemic shock. Hepatocellular carcinoma has also been
reported in women taking estrogen-containing oral contraceptives. The
relationship of this malignancy to these drugs is not known at this time.