17 July 2002
Study Highlights Potential Risk Following Prolonged Use Of Oestrogen-Only HRT
Women taking oestrogen-only hormone replacement therapy should discuss with their doctors the risks and benefits of long
term treatment with oestrogen at their next visit, Ministry of Health spokesperson Dr Stewart Jessamine said today.
This advice follows the publication of a United States Cancer Institute (NCI) study examining the risk of developing
ovarian cancer in women using oestrogen-only hormone replacement therapy (HRT).
Dr Jessamine said "previous research on whether oestrogen-only HRT was associated with an increase in the risk of
developing ovarian cancer has been inconclusive."
"While the NCI study does not provide a definitive answer, it does suggest that there may be a small increase in the
chance of developing ovarian cancer for women who have taken oestrogen-only HRT for 10 or more years. The study found
that in women who had taken oestrogen-only HRT continuously for 10 or more years, ovarian cancer developed in 6 per
10,000 women per year, compared to 4 in 10,000 women per year for women of a similar age who were not taking any form of
HRT."
Dr Jessamine said; "the study contains a number of potential flaws which limit the weight that can be given to the
findings. As the study was conducted on patients first treated in the 1970's using higher doses of oestrogen than are
used nowadays, it is difficult to extrapolate the findings of this study to patients currently on oestrogen-only HRT.
Further research is still needed to determine whether the small increase in risk of ovarian cancer reported in this
study persists at the lower doses of oestrogen used in modern treatment regimens."
Oestrogen-only HRT is quite different from the combination HRT that was the subject of the recently published Women's
Health Initiative study, as only one hormone (oestrogen) is used. Oestrogen-only HRT is predominately used in NZ only by
women who have had a hysterectomy and is used less commonly than combination HRT (oestrogen and progesterone).
"The NCI study raises the possibility that prolonged oestrogen-only HRT may be associated with an increase in the risk
of developing ovarian cancer. Until we have more thoroughly reviewed all the research on this subject, and sought advice
from our expert advisory committee, the NCI study is insufficient to lead to the Ministry issuing new prescribing advice
on oestrogen-only HRT." Dr Jessamine said.
"The study is further evidence, however, that prolonged use of any form of HRT should only take place on the basis of a
careful assessment of the risks and benefits for each individual. In the light of the information published in recent
studies, doctors should certainly be discussing with their patients the risks and benefits of prolonged HRT as set out
in the NZ Guidelines for HRT prescribing. These guidelines, promulgated by the NZ Guidelines group, already advise
prescribers not to routinely use HRT for prolonged periods in menopausal women." Dr Jessamine said.
The guideline, which was updated as recently as 2001, is already scheduled for review following publication of the WHI
study. Dr Jessamine said: " The Ministry will now be asking the NZ Guidelines group to include consideration of the NCI
study in this review".
Products used for oestrogen-only HRT include:
|----------------------------------+----------------------------------| |
Patches | Tablets |
|----------------------------------+----------------------------------| |
Climara | Estrofem | |
Estraderm TTS | Ethinyloestradiol Tab | |
Femtran | Premarin | |
| Progynova |
|----------------------------------+----------------------------------|