This finding is the latest to come from evidence provided by the world's largest international study of breast cancer treatment, the ATAC trial, which compared the aromatase inhibitor anastrozole with breast cancer's current gold standard hormone treatment tamoxifen, and with both treatments combined.
The trial, involving more than 9,000 post menopausal women in 21 countries, last year revealed that over a median follow-up of patients of 33 months, anastrozole enhanced disease-free survival by 19% and cut the incidence of new tumours in the opposite breast by 58% compared to tamoxifen. This represented an absolute difference of 1.8% in favour of anastrozole. An update at 47 months median follow up showed that the gap had widened to an absolute difference of 2.6% in favour of the newer drug. Overall survival comparisons from the trial should be available next year.
Professor Anthony Howell, chairman of the ATAC steering committee, told a news briefing at ECCO 12 the European Cancer Conference, that while it was clear that further results were adding to the evidence that anastrozole may in the future supplant tamoxifen doctors needed to be cautious. "We should still wait for that overall survival data next year," he said.
A concern about anastrozole has been the risk of bone fractures. Depriving the body of oestrogen reduces the risk of breast cancer recurring because many breast cancers 'feed' off this hormone. But, one consequence of oestrogen deprivation is that bones become vulnerable. Aromatase inhibitors such as anastrozole produce profound oestrogen deprivation so it would not be unexpected that women on anastrozole might be more at risk of fractures than those on
Contact: Margaret Willson
Federation of European Cancer Societies