Anastrozole can be used to treat ductal carcinoma in situ, according to the findings of a major trial.
British researchers have shown the drug is as effective as tamoxifen in a major clinical trial.
The randomised, controlled trial involved some 2,980 post-menopausal women with DCIS in 14 countries.
Patients received one of the drugs for five years after surgery and were then tracked for periods of about seven years. Some 144 women developed breast cancer and 69 died – four of them from the disease.
The study, reported in The Lancet, found that anastrozole was linked to an 11% lower rate of cancer recurrence than tamoxifen – but that this was not statistically significant.
The researchers say patients suffered a different range of side effects from the two drugs – but overall the number of these events was less than expected, making statistical analysis hard.
Researcher Professor Jack Cuzick, from Queen Mary University of London, said: “We found that anastrozole and tamoxifen had similar overall efficacies, with slightly better outcomes for those who took anastrozole. But more importantly, because of their very different side-effects, anastrozole can be offered as an alternative for patients who may not tolerate tamoxifen as well or have previous illnesses making tamoxifen unsuitable.
“Now we know that anastrozole is effective for treating hormone sensitive ductal carcinoma in situ, women will have a greater choice of treatments to suit their own previous medical histories and tolerability of medications.”
Anastrozole versus tamoxifen for the prevention of locoregional and contralateral breast cancer in postmenopausal women with locally excised ductal carcinoma in-situ (IBIS-II DCIS): a double-blind, randomised controlled trial. The Lancet 11 December 2015; doi:10.1016/S0140-6736(15)01129-0 [abstract]
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