Tuesday, June 25, 2013

More evidence of powerful breast cancer prevention


We have previously pointed to the strong evidence that use of selective estrogen receptor modulators (SERMs) substantially reduces risk of breast cancer. New updated data has been published in the British journal Lancet (May 25, 2013). The original data from all patients in a number of trials of these agents for prevention for breast cancer were combined using common analytic methods. The authors report that across 9 prevention trials and 83,339 women randomized to SERMS and followed for an average of 65 months, had a significant 36% reduction in invasive breast cancer. The reduction in risk is stronger for estrogen receptor positive breast cancer.

New insights in this report include the protection from taking SERMs persists for 5 or more years after stopping. Also risk of vertebral (spine) fractures was significantly reduced by 34%. This improves the benefit to risk trade-off that this and other drug based prevention strategies require.

The good news is that the adverse effects form taking SERMs are now well documented and low frequency.

From this analysis the authors draw on the extended follow-up and estimate that for every 42 women treated with a SERM for 5 years one case of breast cancer will be prevented within 10 years of beginning therapy.  This is similar to our early post in which we pointed to our paper from 2008 showing that for 5 years of use among women 65 to 69 one case of invasive breast cancer would be prevented for every 43 women treated, and for women 60 to 64 in the top 10% of breast cancer risk in the population, one case would be prevented for every 53 women given the chemoprevention drug.

We recently noted that use of SERMs is much lower than might be expected given the substantial reduction in breast cancer with use of these drugs. The FDA approved the use of Tamoxifen for primary prevention of breast cancer in both premenopausal and postmenopausal women at high risk. This approval was in 1998. In 2007, the FDA approved Raloxifene for primary prevention of breast cancer among postmenopausal women.

And for breast cancer prevention, see: Cancer News in Context: Breast cancer prevention


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