Isn’t it time to use what we know to prevent breast cancer?

In a recent analysis of updated data from the National Health Interview Survey, Dr. Erika Walters and colleagues report on the use of Tamoxifen and Raloxifene by US women (see report1,2. These two selective estrogen receptor modulators bind estrogen receptors in breast tissue and reduce the action of estrogen on breast cells. Randomized controlled trials show that these two drugs significantly reduce the risk of developing invasive breast cancer 3,4. The magnitude of risk reduction is thus well established. In these randomized trials a reduction in the order of 50% fewer breast cancers among women taking the drug is seen for each of these agents. Comparing the two drugs head to head showed a more favorable profile of side effects for Raloxifene compared to Ramoxifene 5.
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.
The National Health Interview Survey data show that the use of these two drugs for primary prevention is extremely low. Based on the interview data it is estimated that n 2010 only about 100,000 women are using these drugs specifically for breast cancer prevention. Approximately 300,000 women are using Raloxifene for prevention of osteoporosis.
In a previous analysis of the US population projections we estimated that 8 million women ages 50 to 69, are at sufficient risk to justify use of these agents for prevention of breast cancer (see article). The reduction in breast cancer would exceed any excess side effects. Among these 9 million women some 21,000 cases of breast cancer could be prevented each year. See related post.
There are many barriers slowing our progress from scientific understanding of the causes and prevention of cancer to implementing what we know 6,7. This example highlights some of this delay. Randomized trials published in 1998 and 2004 led to FDA approval for indications to use drugs to prevent breast cancer. Now in 2013 we are still missing the opportunity to prevent thousands of breast cancers. Other strategies like avoiding postmenopausal hormones and increasing physical activity and weight loss can add to the reduction. All theses strategies remain underutilized. Isn’t it time to use what we know to prevent breast cancer?
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References cited
2.      Waters EA, McNeel TS, Stevens WM, Freedman AN. Use of tamoxifen and raloxifene for breast cancer chemoprevention in 2010. Breast Cancer Res Treat. Jul 2012;134(2):875-880.
3.      Fisher B, Costantino JP, Wickerham DL, et al. Tamoxifen for prevention of breast cancer – report of the National Surgical Adjuvant Breast and Bowel Project P-1. J Natl Cancer Inst. 1998;90:1371-1388.
4.      Martino S, Cauley JA, Barrett-Connor E, et al. Continuing outcomes relevant to Evista: breast cancer incidence in postmenopausal osteoporotic women in a randomized trial of raloxifene. J Natl Cancer Inst. Dec 1 2004;96(23):1751-1761.
5.      Vogel VG, Costantino JP, Wickerham DL, et al. Update of the National Surgical Adjuvant Breast and Bowel Project Study of Tamoxifen and Raloxifene (STAR) P-2 Trial: Preventing breast cancer. Cancer Prev Res (Phila). Jun 2010;3(6):696-706.
6.      Colditz G. Cancer culture: epidemics, human behavior, and the dubious search for new risk factors. Am J Public Health. 2001;91:357-359.
7.      Colditz GA, Wolin KY, Gehlert S. Applying what we know to accelerate cancer prevention. Sci Transl Med. Mar 28 2012;4(127):127rv124.

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