Dr Allan Zimet, AMA Spokesperson, with Chris Uhlmann, 'Breakfast', Radio 2CN

Most of the papers, the radio news and 'AM' have been reporting on the cancellation of a major US trial on the risks and benefits of combined oestrogen and progestogen treatment because of an increased risk of breast cancer.

As a result, the New South Wales Cancer Council has called for access to the treatment to be restricted, saying the risks outweigh the benefits. But that's not a view that's held by all the experts. Dr Allan Zimet is an oncologist and spokesman on this issue for the Australian Medical Association. Good morning.

ZIMET: Good morning. How are you?

UHLMANN: Good, thank you. Can you tell us a little about hormone replacement therapy, first?

ZIMET: Well, hormone replacement therapy is used by about 600,000 women around Australia. That's the estimate we currently have. They're on it for a variety of reasons. The majority of women would be on it for menopausal symptoms such as hot flushes, vaginal dryness, things like that.

Most of the women are on it short term, not for long-term. There has been a trend in the last few years, however, to put women who've had increased risk of coronary artery disease or osteoporosis on to this sort of treatment to try and prevent heart attacks, to try and prevent stroke.

UHLMANN: Now women at the moment are on a combined oestrogen/progestogen hormone replacement therapy. That was because, in the 1980s, our studies showed that oestrogen alone carried a risk of cancer.

ZIMET: Absolutely, although not all women are on that combined treatment. You must remember that women who've had their uterus taken out would be just on oestrogen alone, and that certainly is not the subject of this alert today.

UHLMANN: Now, can you tell us about this alert. What is the concern, how big was the study?

ZIMET: The concern is that there is an increased risk of breast cancer and an increased risk of heart disease in women who are on hormone replacement therapy. It's certainly a very large study, about 16,000 women, randomised into half having hormone replacement therapy and half having placebo tablets.

The concern is that there is very small increased risk of breast cancer in the women who are on hormone replacement therapy after an average of five years of treatment. So, a long time of treatment, certainly longer than we would be generally using in Australia.

UHLMANN: But the New South Wales Cancer Council is saying that women should stop their treatment immediately. Do you think that's good advice?

ZIMET: I don't think that's particularly good advice. I think that women need to discuss their individual circumstances with their doctor. They need to make sure that they're on the combined pill, not the oestrogen alone pill, and they need to discuss it and get rational advice from their doctor.

Certainly, there are other studies that don't seem to show a major risk of breast cancer but this is a very large study and one will need to take this study into consideration, major consideration, and over the next couple of weeks we will be analysing the data fairly carefully.

UHLMANN: When you say that there was a small risk, it says a 26% increase in the risk of developing breast cancer after three years.

ZIMET: In women who are on - if you take 10,000 who are on HRT and compare them with 10,000 women who are not on HRT, eight extra women will develop breast cancer. So it is a risk, but still a very tiny risk. And certainly, one needs to look at the overall lifestyle and other factors before advising women to go off HRT. And the risk seems to come on after five years, at five years rather than at three years.

UHLMANN: What do you then think of what the New South Wales Cancer Council has had to say? Is it a knee jerk response?

ZIMET: I think the New South Wales Cancer Council is saying quite rightly that we need to review all the data. We need to look at what we should be advising women to do but we also need to be doing this in a careful, considered manner rather than jumping the gun fairly quickly.

UHLMANN: Dr Zimet, can you appreciate that women might be very confused today because we do get conflicting results from these sorts of studies?

ZIMET: I think women certainly have a right to get the best information and this is an example of a major study set up by the National Institute of Health in the United States trying to answer a very difficult question as to whether hormone replacement therapy does prevent breast cancer. And that was one of the thoughts, or whether it does prevent coronary artery disease. And unfortunately the results of this study seem to show neither.

UHLMANN: All right, finally then, so your suggestion today to women who are on hormone replacement therapy would be to consult their doctor?

ZIMET: To consult their doctor, not to panic because the risk of events is small but certainly one needs to talk to their doctors very carefully.

UHLMANN: Dr Zimet, thank you.

Ends