The American Society of Clinical Oncology (ASCO) recently issued a newly updated clinical practice guideline on pharmacologic prevention interventions for premenopausal and postmenopausal women who are at increased risk for breast cancer. Compared to the previous version of the guideline, this third update, published today in the Journal of Clinical Oncology,1 strongly recommends discussing the use of tamoxifen with premenopausal women and tamoxifen and raloxifene (Evista) with postmenopausal women at increased risk. There is also a recommendation for discussing the option of exemestane as an alternative option for postmenopausal women.
The update also stresses the need for ongoing research on approaches to increase tamoxifen and raloxifene use in breast cancer prevention among women who are at higher risk of developing invasive breast cancer. Currently, only a small percentage of eligible women have the discussion of breast cancer risk reduction with their doctors.
Key Recommendations
The key recommendations of the guideline are as follows:
- Tamoxifen (20 mg per day orally for 5 years) should be discussed as an option to reduce the risk of invasive, estrogen receptor (ER)-positive breast cancer in premenopausal or postmenopausal women.
- Raloxifene (60 mg per day orally for 5 years) should also be discussed as an option to reduce the risk of invasive, ER-positive breast cancer in postmenopausal women.
- Exemestane (25 mg per day orally for 5 years) should be discussed as an alternative to reduce the risk of invasive, ER-positive breast cancer in postmenopausal women. This recommendation is based on encouraging data from a single clinical trial that showed up to a 70% reduction in overall and ER-positive invasive breast cancer incidence with exemestane compared to placebo over a 3-year period.
All three agents should be discussed (including risks and benefits) with women aged 35 years or older without a personal history of breast cancer who are at increased risk of developing invasive breast cancer, based on risk factors such as the woman’s age, race, and medical and reproductive history.
“Not every woman should use these preventive agents, but we believe women who are at increased risk for breast cancer should be given the option, because in some cases the magnitude of the risk reduction is large. For some women, these therapies can reduce the risk of breast cancer by up to 50%,” said Kala Visvanathan, MBBS, FRACP, MHS, Co-Chair of the Guideline Panel and Associate Professor of Epidemiology and Oncology at the Johns Hopkins Bloomberg School of Public Health and the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center.
Risks and Benefits of Therapy
The guideline provides new insight on the risks and benefits for tamoxifen and raloxifene use in postmenopausal women. The risk and benefit profile for both agents varies by age, race, level of breast cancer risk, and history of hysterectomy. The guideline emphasizes that women should discuss both the risks and benefits of these drugs with their doctors before deciding whether to take these drugs for prevention.
“We now have a better understanding of the net health benefits of these interventions. This knowledge will help us identify those women in which the benefit is greater than the risk,” Dr. Visvanathan said.
The guideline specifies that tamoxifen and raloxifene are not recommended for use in women with a history of deep vein thrombosis, pulmonary embolus, stroke, transient ischemic attack, or during prolonged immobilization. In addition, tamoxifen is not recommended for use in women who are pregnant, may become pregnant, or nursing mothers, and should not be used in combination with hormone therapy.
ASCO has also developed clinical tools and resources to help doctors implement this guideline. The resources include a decision aid tool, which uses straightforward charts to explain the risks and benefits of breast cancer chemoprevention. ASCO has also developed a companion patient guide and graphic, available on ASCO’s cancer information website, www.cancer.net.
More information on the new guideline and clinical tools and resources can be found at www.asco.org/guidelines/bcrr. ■
Reference
1. Visvanathan K, Hurley P, Bantug E, et al: Use of pharmacologic interventions for breast cancer risk reduction: American Society of Clinical Oncology Clinical Practice Guideline. J Clin Oncol. July 8, 2013 (early release online).
