In a meta-study covering nine trials and 35,129 women, 5 years of Tamoxifen was compared to 5 years of AIs (Report: The Lancet, October 2015).
AIs were superior in preventing recurrence throughout the 5 years of therapy and also reduced the 10-year risk for breast cancer mortality by 15 per cent.
Conversely, taking tamoxifen for 5 years was associated with higher rates of recurrence and breast cancer mortality against taking tamoxifen for 2 to 3 years, followed by AI therapy.
Among women receiving split therapy with tamoxifen, then AIs, the risk for recurrence was higher only during the period of tamoxifen use. Breast cancer mortality outcomes were similar in comparing 2 to 3 years of tamoxifen, then AI therapy, with AI therapy for 5 years. AI therapy was also superior to tamoxifen in the outcome of all-cause mortality.
Compared with tamoxifen, AIs were associated with a lower rate of endometrial cancer, but AIs promoted higher rates of fracture. Bisphosphonate treatment may help reduce fracture rates.