Led by the National Cancer Research Institute and the University of Genoa in Italy, researchers pooled data from two studies comparing five year treatment with tamoxifen alone or tamoxifen for two to three years followed by an aromatase inhibitor for the remaining treatment period.
The study demonstrates that the clear survival benefit was also achieved without an increased risk of death from other causes, which is a significant risk associated with tamoxifen.
Hormone modulating therapies are used as adjuvant to primary surgical treatment for a period of five years. Tamoxifen was the first estrogen modulator shown to increase survival and reduce the risk of breast cancer recurrence. However, tamoxifen is associated with increased risk of death from other causes, such as strokes and endometrial cancer.
Aromatase inhibitors work in a different way to lower estrogen levels. Recent evidence shows aromatase inhibitors used alone or in follow-up after two years of tamoxifen therapy demonstrates clear and, in some cases, improved reduction of recurrence risk. However, there is conflicting evidence about mortality benefits.
“This pooled analysis provides solid evidence that switching to an aromatase inhibitor following a few years of tamoxifen treatment, implies a mortality benefit over continued tamoxifen and that the benefit on breast cancer-related mortality is mainly due to the effect of switching,” concluded the authors.