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CANCER experts have challenged doctors to take a bold step and embrace preventive drugs for patients at high risk of developing breast cancer.
Strong evidence shows selective oestrogen receptor modulators (SERMs) such as tamoxifen can reduce breast cancer risk by 40% in women at moderate or high risk.
Yet SERMs are rarely used for this indication, even in women at high risk, according to a Perspectives article in the MJA. (1)
The authors noted that the National Breast and Ovarian Cancer Centre (Cancer Australia) management recommendations have been revised to suggest that risk-reducing therapy with tamoxifen or raloxifen be considered for women with a moderate or high risk of breast cancer.
“General practitioners and breast surgeons are ideally placed to identify women at increased risk and discuss, prescribe and monitor risk-reducing medication”, the authors wrote.
Cancer Council Australia chief executive, Professor Ian Olver, applauded the suggestion but noted the move would represent a paradigm shift for doctors and patients.
“We are not used to taking pharmaceuticals as preventive agents [for cancer] so we have to introduce this whole new concept”, he said.
“Another barrier is that you’ve got a well person taking a medication that will have some side effects — so it’s probably a matter of educating the public as well as GPs, as they are in the right place to advise about this”, he said.
The authors noted that, even though there were side effects with SERMs, the absolute risk of a serious event was not large. For instance, although tamoxifen doubled the risk of blood clots, the baseline risk of a clot was very small. The risk of a blood clot among premenopausal women taking tamoxifen was similar to that of women taking the oral contraceptive pill, the authors wrote.
They also noted that although these drugs were not subsidised on the Pharmaceutical Benefits Scheme for this indication, they were relatively inexpensive — less than $1 per day for tamoxifen — and likely to be within the means of most patients.
Breast oncologist and director of the Macquarie University Cancer Institute, Professor John Boyages, agreed that SERMs were an effective option in breast cancer prevention.
“We really need to keep selective oestrogen [receptor] modulators in mind for women at moderate or high risk of breast cancer”, he said. “We know for patients with invasive breast cancer, even taking [tamoxifen for] 2 years … can have life-long benefit and this is probably true when we use it for prevention.”
Professor Boyages said the key issue was deciding on the starting point for treatment.
“It’s a treatment that is only for women considered very high risk. That includes women who have had breast cancer before, have the BRCA gene mutation, have a family history or have had a biopsy showing changes in their breast tissue such as significant atypical hyperplasia or lobular carcinoma in situ”, he said.
Professor Boyages said the risk reduction had to be balanced against the side effects of taking tablets for many years.
Online risk assessment tools can be found on the Cancer Australia website canceraustralia.nbocc.org.au/fraboc and at ems-trials.org/riskevaluator.
Cancer Australia has also developed at fact sheet about contraindications and the practicalities of prescribing.
According to the MJA authors, these online tools can help doctors better assess breast cancer risk to evaluate whether a patient may benefit from SERMs.
– Amanda Bryan
Posted 12 December 2011