Written by Rashelle Predovnik Monday, 10 May 2010 16:10
HEALTHY WA women are being asked to take part in an international breast cancer study to see if the drug Anastrozole can prevent the disease in women most at risk.
The IBIS II study is the only clinical trial worldwide to investigate whether Anastrozole can prevent breast cancer in postmenopausal women who are at increased risk of the disease.
The study is being conducted in Australia and New Zealand by the Australian New Zealand Breast Cancer Trials Group and is coordinated internationally by Cancer Research UK.
Professor of Surgical Oncology at the University of Western Australia Professor Christobel Saunders is WA’s chief investigator and she says recruiting healthy women for the study has been a real challenge.
“These are well women we are recruiting, not women who have had breast cancer,” she says.
“Nevertheless, these women are at higher risk of getting breast cancer but most of them will still fortunately never get cancer in their lifetime.
“So the only way you can prove by comparing the Anastrozole drug with placebo that it does lower the risk is to have very large numbers of women otherwise you will never get that result.”
Clinical Trials Coordinator Giuliana D'Aulerio says to date 2962 women have been recruited for the international study, which aims to recruit 6000 women.
IBIS-II follows on from the IBIS-I study which showed the drug Tamoxifen could prevent breast cancer in some women at increased risk.
However, Prof Saunders says although Tamoxifen reduced the incidence of breast cancer in women it didn’t show a survival advantage so the next phase was to use some of the newer anti-breast cancer drugs such as Anastrozole.
“Anastrozole was first used extensively in the 1990s and one large trial first published in 2003 really confirmed suspicions that it decreased the chance of getting a secondary breast cancer if you already had one,” she says.
“These drugs not only prevent cancer whilst you are on them but there’s a kind of hang-over effect after you’ve finished them, and there are some good reasons to suspect biologically why that may be the case.
“So we think that even just five years of treatment with a drug will protect a woman for life but you need to follow them up for a long time to make sure that’s true.”
Significantly, if the IBIS II trials do in fact show Anastrozole can significantly prevent women at risk from developing breast cancer, ethical questions inevitably arise.
Prof Saunders says all these drugs have potential side effects so the benefits have to be weighed up against the harms of giving people a drug, particularly healthy people.
“I do think the benefit will be if we can identify a very specific, probably relatively small, percent of the population who are at high risk and who would benefit from the drug then you could for a short amount of time offer them something that may be able to prevent it.”
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