Research News

Ten years of tamoxifen works better than five

BMJ 2012; 345 doi: (Published 12 December 2012) Cite this as: BMJ 2012;345:e8383

Tamoxifen helps prevent recurrences and prolongs life in eligible women with early breast cancer. Protection seems to accumulate over time, and in a recent long term trial 10 years of treatment worked significantly better than five. Eligible women who continued tamoxifen had lower mortality overall (639 deaths/3428 v 722/3418; event rate ratio 0.87, 95% CI 0.78 to 0.97), lower mortality from breast cancer, and fewer recurrences than women who stopped after five years. Tamoxifen has a well known carry over effect, and in this trial the mortality benefits became clear only after women had completed their 10 years of treatment.

Women who took tamoxifen for longer had more pulmonary emboli (rate ratio 1.87, 1.13 to 3.07) and more endometrial cancer (1.74, 1.30 to 2.34) than controls. But they had less ischaemic heart disease (0.76, 0.60 to 0.95). The authors and a linked comment (doi:10.1016/S0140-6736(12)62038-8) agree that the benefits of longer treatment outweigh the risks.

Women in these analyses had early breast cancers that expressed oestrogen receptors. Most were postmenopausal when they were recruited in 1996, after five years of treatment with tamoxifen. Newer antioestrogens are now available, and others will have to evaluate where agents such as aromatase inhibitors fit into the long term therapeutic picture, says the comment. But for women already taking tamoxifen, longer treatment is beginning to look substantially more protective than stopping at five years.


Cite this as: BMJ 2012;345:e8383