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A new study claims that breast cancer patients taking tamoxifen will find that switching to an aromatase inhibitor within three years significantly improves survival rates.
The study – published in the March 15 issue of Cancer and led by Prof Francesco Boccardo, of the National Cancer Research Institute and the University of Genoa in Italy – pooled data from two studies comparing five-year treatment with tamoxifen alone (415 women) or tamoxifen for two to three years followed by an aromatase inhibitor for the remaining treatment period (413 women).
The data showed that compared to treatment with tamoxifen alone, all-cause mortality risk and breast-cancer-related mortality risk both fell significantly for women switching to an aromatase inhibitor. In addition, there was no increased risk of death from other causes in women who were prescribed the aromatase inhibitor.
The researchers note that while tamoxifen was the first oestrogen modulator shown to increase survival and reduce the risk of breast cancer recurrence, it is associated with higher risk of death from other causes, such as strokes and endometrial cancer. Despite this risk, they say, tamoxifen remains an extensively used and popular treatment.
Aromatase inhibitors such as anastrozole lower oestrogen levels in a different way. The researchers say recent evidence shows that inhibitors used alone or in follow-up after two years of tamoxifen therapy demonstrate “clear and, in some cases, improved reduction of recurrence risk”. However, they acknowledge that there is conflicting evidence regarding mortality benefits.