Extended use of breast cancer drug tamoxifen linked to increased endometrial cancer risk


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New evidence published in the British Journal of Surgery has indicated a troubling link between long-term use of the breast cancer drug tamoxifen and an increased risk of developing endometrial cancer.

The study’s investigators analysed a range of randomised clinical trials into the risk of endometrial malignancy in the extended use of tamoxifen; on examination of four such studies, it was found that extending tamoxifen use from the standard five years of use to ten years increased cumulative risk of malignancy from 1.2% to 3.2%.

The team also conducted a systematic review into whether or not routine endometrial surveillance had an effect on securing earlier detection times and the incidence of endometrial malignancy. In four studies evaluating the value of such screening in five-year cohorts, it was noted that “endometrial cancer rates of up to 2% were reported, which is higher than rates in the large extended tamoxifen trials.”

The researchers noted that more work still needs to be done on the topic, but screening for endometrial cancer could be warranted in patients receiving extended tamoxifen therapy.

“Although it is difficult to make clear evidence‐based recommendations on endometrial surveillance in the setting of extended therapy because of the sparsity of robust results, a practical approach may be to screen all patients using endometrial ultrasonography after five years on tamoxifen,” the authors said.

Lead author Dr Christina Fleming of St. Vincent’s Hospital Group in Dublin also added: “There is a paucity of clear evidence on how we should best manage endometrial cancer risk in extended tamoxifen therapy. This is a research area that requires immediate focus with expansion of extended tamoxifen therapy regimes.”

Matt Fellows