A newly updated guideline from the American Society of Clinical Oncology (ASCO) states that post-menopausal women who are at increased risk for breast cancer could benefit from taking either tamoxifen or raloxifene to reduce their risk of developing the disease. The previous version of the guideline only recommended tamoxifen for this purpose.

The guideline also incorporates long-term follow-up information on the risks and benefits of using tamoxifen for breast cancer risk reduction in pre- and post-menopausal women. Further, certain side effects, including blood clots and vasomotor symptoms like hot flashes, sweats, and menstrual irregularities, did not continue after treatment. The guideline also includes recommendations about the use of aromatase inhibitors, and retinoids to lower breast cancer risk.

The key recommendations are as follows:

  • Pre- and post-menopausal women who have an increased risk of breast cancer may take tamoxifen for five years to reduce their risk of ER-positive invasive breast cancer for up to 10 years. It is not known if there is a benefit to taking tamoxifen for more than five years.
  • Post-menopausal women at an increased risk for breast cancer may also consider raloxifene for five years to reduce their risk of developing ER-positive invasive breast cancer. Raloxifene may be used for longer than five years in post-menopausal women with osteoporosis in whom breast cancer risk reduction is a secondary benefit.
  • The use of aromatase inhibitors or retinoids to reduce the risk of breast cancer is not currently recommended outside of a clinical trial.

In the United States, breast cancer is the second-most common cause of death from cancer for women, after lung cancer. According to data from the American Cancer Society, more than 192,000 women will be diagnosed with breast cancer in 2009.

“It is important that women at increased risk of breast cancer be given the option of considering treatments that may reduce their risk,” said Kala Visvanathan, MD, MHS, lead author of the guideline and Assistant Professor in Epidemiology and Oncology at the Johns Hopkins Bloomberg School of Public Health and the School of Medicine.

The guideline also clarified which women should not take these drug therapies. Raloxifene and tamoxifen are not recommended for women with a history of blood clots or stroke, and raloxifene is not recommended for pre-menopausal women.

“Women taking these drugs will need to consider both the benefits and adverse effects of each agent,” Dr. Visvanathan said. “It is important for women who are considering taking tamoxifen or raloxifene to have this discussion with their health provider before deciding whether to take these drugs.”

In addition, the guideline states that breast cancer risk should be calculated periodically, because a woman’s risk of breast cancer increases throughout her lifetime. Standardized tools are available to assess a woman’s breast cancer risk.

The guideline uses the National Cancer Institute’s Breast Cancer Risk Assessment Tool to define which women have a higher risk of developing breast cancer. The Breast Cancer Risk Assessment Tool uses a woman’s age, race, and medical history to determine her risk for breast cancer. In addition, women with lobular carcinoma in situ (LCIS), a condition in which abnormal cells are found in the lobules or glands of the breast, are considered to be at increased risk.

In conjunction with this guideline, ASCO has developed clinical tools and resources that summarize the findings and recommendations. These resources include a decision aid tool, which uses straightforward charts and diagrams to explain the risks and benefits of breast cancer chemoprevention to women and their families. The updated practice guideline, decision aid tool, and other tools are available at www.asco.org/guidelines/bcrr. ASCO also has developed a corresponding patient guide, available on ASCO’s patient Web site, www.cancer.net.

For full article, Updated Guideline on Breast Cancer Risk Reduction


“American Society of Clinical Oncology Clinical Practice Guideline Update on the Use of Pharmacologic Interventions Including Tamoxifen, Raloxifene, and Aromatase Inhibition for Breast Cancer Risk Reduction” by Kala Visvanathan, et al.

This guideline is being published in the May 26 issue of the Journal of Clinical Oncology (JCO), the semi-monthly peer-reviewed journal of the American Society of Clinical Oncology (ASCO), the world’s leading professional society representing physicians who treat people with cancer.


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