Anastrozole

No significant difference in recurrence rates among women with DCIS taking anastrozole or tamoxifen

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• published: 06 Jan 2016
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Prof Cuzick talks to ecancertv at SABCS 2015 about the results from the phase III IBIS-II DCIS clinical trial that compared the efficacy and safety of anastrozole versus tamoxifen in postmenopausal women with estrogen-receptor positive ductal carcinoma in situ (DCIS). Third generation aromatase inhibitors (AIs) such as anastrozole have been shown to be a more effective treatment option than tamoxifen for postmenopausal women with ER positive invasive breast cancer. However, it is not known whether AIs have the same benefit over tamoxifen in women with hormone-sensitive DCIS. The IBIS-II DCIS study therefore directly set out to compare the two hormonal therapies, which were given over a 5-year period to almost 3000 women with locally excised disease. Dr Cuzick discusses data from a first analysis, at a median of almost 7 years of follow, and noted that there was no significant different between the two study arms. While apparently as effective as each other in the DCIS setting, the two hormonal therapies had very different side effect profiles. The side effects seen were those commonly attributed to these drugs, with an increased risk of endometrial cancer and thrombotic disease with the use of tamoxifen and more musculoskeletal abnormalities and bone loss with anastrozole.