Another HRT trial stopped as women with previous breast cancer found to be at high risk of recurrence
Another hormone replacement therapy trial has been terminated because initial results show that women with a history of breast cancer allocated to receive HRT for menopausal symptoms were at “unacceptably high” risk of breast cancer compared with women allocated to best treatment without hormones.
The HABITS (hormonal replacement therapy after breast cancer — is
it safe?) trial was an open randomised clinical trial started in Sweden
in 1997, in which 434 women previously treated for breast cancer were
allocated to either HRT or best symptomatic treatment without hormones.
Treatment with adjuvant tamoxifen was allowed.
At a median follow up of 2.1 years, data from 345 women showed that 26
out of 174 women in the HRT group had a new breast-cancer event compared
with seven out of 171 women in the non-HRT group (relative hazard 3.5,
95 per cent confidence interval 1.5–8.1). Eight serious adverse
effects were reported in the HRT group compared with four in the non-HRT
group. The steering committee decided to stop the trial and to recommend
that all patients on HRT stop the treatment.
Data were pooled with a similar trial taking place in Stockholm, where
women on HRT were found to be less likely to have a breast cancer event
than those not on HRT (relative hazard 0.82). There are not yet enough
data to explain why the two trials differ in findings, but the investigators
of the Stockholm trial also decided to terminate, due to anticipated
difficulties in recruitment and compliance. The authors acknowledge that
results may change after the complete assessment of all patients’ original
records (Lancet 2004;363:453).
Authors of an accompanying commentary (ibid, p410) say: “Although
the HABITS trial may arguably not be the definitive word on the use of
HRT in women with breast cancer, it will probably be the last word when
considered in the context of our evolving understanding of the effects
of HRT on chronic disease in women.” They note that the results
are consistent with the women’s health initiative trial, which
was terminated in 2002 (PJ, 13 July 2002, p43). This in turn prompted
termination of the
women’s international study of long duration
oestrogen (PJ, 2 November 2002, p633). The authors say that despite study
limitations, such as unblinding and lack of placebo controls, the conclusions
drawn from the HABITS trial can now reasonably guide clinical practice
for women with breast cancer. |
The
Pharmaceutical Journal