The American Society of Clinical Oncology (ASCO) has released updated guidelines for pharmacologic interventions among women at an increased risk of breast cancer. This third update of the guidelines, published in the Journal of Clinical Oncology, includes the addition of Aromasin® (exemestane) for the prevention of breast cancer in postmenopausal women at risk for estrogen receptor (ER)-positive disease.
Women with a strong family history of breast cancer and women who carry the BRCA1 and BRCA2 genes are at an increased risk of developing breast cancer and may opt to take more aggressive preventive measures, including the use of “chemoprevention”, or drugs that block the effects of estrogen—because estrogen causes some cancers to grow. There are two types of drugs used to block estrogen. Selective estrogen receptor modulators (SERMs) are drugs that block estrogen receptors within the breast cells, thereby reducing estrogen-stimulated growth. Tamoxifen and Evista® (raloxifene) are examples of SERMs. Aromatase inhibitors suppress the production of estrogen in postmenopausal women. Aromasin is an aromatase inhibitor. Each of these drugs has been shown to reduce the risk of breast cancer in women at high risk of the disease.
The updated recommendation guidelines from ASCO are as follows:
For premenopausal women:
- The use of 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
For postmenopausal women, there are now three options. ASCO strongly recommends that one of the following be considered in order to reduce the risk of invasive, estrogen receptor (ER)-positive breast cancer:
- Tamoxifen (20 mg per day orally for 5 years)
- Evista (60 mg per day orally for 5 years)
- Aromasin (25 mg per day orally for 5 years). (Note: This is a new recommendation, which was based on data from a clinical trial that showed up to a 70 percent reduction in overall and ER-positive invasive breast cancer incidence compared to placebo.)
What’s more, the recommendations state that all three agents should be discussed with women aged 35 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 age, race, and medical and reproductive history.
Not all women will benefit from the use of these preventive agents. It is important that doctors and women discuss the risks and benefits of each drug in order to determine the best approach. That said, only a small percentage of eligible women have this discussion with their doctors or even consider these medications. As such, the guidelines also stress the need for ongoing research to determine approaches to increase the use of these drugs in women who will benefit from them.
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. Journal of Clinical Oncology. Published early online July 8, 2013. doi: 10.1200/JCO.2013.49.3122