Women face dilemma over HRT use
For many women taking hormone replacement therapy (HRT) the benefits of short-term use will outweigh the risks, according to the Committee on Safety of Medicines. Women using HRT in the longer term must be
made aware of the increased incidence of breast cancer and other adverse
effects, it says.
The CSM’s advice follows publication of the Million Women Study
in The Lancet last week (PJ, 9 August, p169), which revealed the levels
of risk associated with different types of HRT (see Panel).
Million Women Study
The Million Women Study recruited 1,084,110
women aged 50–64
years between 1996 and 2001. Half had used HRT. Incidence of
breast cancer was increased for current users of combined HRT
(adjusted relative risk 2.00, 95 per cent confidence interval
1.88–2.12, P<0.0001), oestrogen-only HRT (1.30, 1.21–1.40,
P<0.0001) and tibolone (1.45, 1.25–1.68, P<0.0001).
The relative risks were increased separately for oral, transdermal
and implanted oestrogen-only formulations. |
Use of HRT containing oestrogen plus progestogen was shown to double
a woman’s chance of developing breast cancer. This means that for
every 1,000 women who use combined HRT continuously for five years, there
will be an extra six cases of breast cancer diagnosed. For oestrogen-only
products the risk is lower, with an extra one or two cases of the disease
being diagnosed for every 1,000 women who use this type of HRT for five
years.
The study also examined the risk associated with tibolone (Livial), another
type of drug used to relieve menopausal symptoms. The investigators found
that tibolone use was associated with an increased risk of breast cancer,
although the risk was not as high as with combined HRT.
Dr Nuttan Tanna, specialist pharmacist at Northwick Park menopause clinical
and research unit, North West London NHS Trust, told The Journal the
study confirmed much of what is known about the breast-cancer risk associated
with HRT. “Women considering using HRT need to decide how bad their
menopausal symptoms are and should have an individualised risk benefit
evaluation, with the opportunity to consider their increased risk of
breast cancer with time,” she said. What the study did not do,
however, was clarify the length of time that women can safely use HRT. “We
need further research before we can give patients a definite time scale,” she
added.
Commenting on the study, Professor Gordon Duff, chairman of the CSM,
said: “We ... realise that these findings may present women and
their doctors with a dilemma about long-term HRT treatment. However,
what this study clearly shows is that, in all cases, the additional risk
of breast cancer begins to decline when HRT is stopped and by five years
reaches the same level as in women who have never taken HRT. The new
findings mean that it is even more important that each decision to start
HRT is made on an individual basis, and is reassessed at least annually.” |
