Both tamoxifen and Evista (chemical name: raloxifene) are hormonal therapy medicines and have been shown to lower the risk of breast cancer in women at high risk for breast cancer because of strong family history or a known genetic mutation. Still, research has found that less than 25% of women at high risk for breast cancer start or complete the full course of preventive hormonal therapy.
A study suggests that a health care professional’s recommendation is the most important factor affecting decisions by women at high risk for breast cancer on whether to take preventive hormonal therapy.
The research was published online on Oct. 4, 2017 by the journal Cancer Prevention Research. Read the abstract of “NRG Oncology/National Surgical Adjuvant Breast and Bowel Project Decision-Making Project-1 Results: Decision Making in Breast Cancer Risk Reduction.”
Tamoxifen and Evista are both SERMs (selective estrogen receptor modulators), a type of hormonal therapy medicine. SERMs block the action of estrogen in breast and certain other cells by sitting in the cells’ estrogen receptors. SERMs don’t affect all estrogen receptors the same way because they’re selective (as the name says). In bone cells, SERMs interact with the receptors the way estrogen does and strengthen bones. In breast cells, SERMs block the receptors’ interaction with estrogen and limit cell growth.
As medicines to lower the risk of breast cancer in high-risk women who have never been diagnosed, tamoxifen and Evista are often taken for 5 years.
In this study, the researchers wanted to rank the factors that affects a high-risk woman’s decision to take a SERM or not.
To do the study, the researchers surveyed 1,023 women at high risk for breast cancer twice:
- the first time was immediately after a counseling session with a health care professional about risk reduction options
- the second time was after they made their decision about taking a SERM
The surveys asked about:
- the choices for breast cancer risk reduction
- the benefits and risks of taking a SERM
- how the information about SERMS and other risk-reducing options were conveyed
Overall, 726 women made a decision about taking a SERM:
- 324 women (44.6%) decided to take a SERM
- 402 women (55.4%) decided not to take a SERM
The other 297 didn’t make a decision about taking a SERM.
The researchers found that the health care professional’s recommendation was the most important factors affecting a woman’s decision about taking a SERM.
Other factors that played a role were:
- attitudes about taking medicine
- worry about developing breast cancer
- trust in the health care professional
- having a family member with blood clotting issues
- personal knowledge about the experiences of other people who had taken a SERM
"We were surprised how clear-cut our findings were," said co-lead investigator Christine Holmberg, Ph.D., senior researcher and lecturer at the Institute of Public Health, Charite-Universitatsmedizin in Berlin, Germany. "The health care professional's recommendation to take a SERM was paramount. None of the other characteristics related to the counseling session came close in importance. We also found that the health care professional's recommendation for taking a SERM was more likely to be followed by women with a positive attitude about taking medication.
"Our research suggests that it is not enough to present medical facts and information about risks and benefits of SERMs to patients who have an increased risk for breast cancer," Holmberg added. "Helping them find the prevention approach that is right for them is crucial. Health care professionals need to take patients' attitudes, beliefs, and experiences into account and make a recommendation, one way or the other."
Both tamoxifen and Evista can cause side effects, some of them serious. Common side effects associated with tamoxifen are:
- blood clots
- a higher risk of endometrial cancer
- leg cramps
- weight gain
- hot flashes
- joint pain
While Evista also may cause blood clots and stroke, women taking Evista are less likely to have these two serious side effects compared to women taking tamoxifen. Evista also may cause:
- hot flashes
- joint pain
- weight gain
Earlier studies suggest these side effects are likely a big part of the reason many women decide not to take tamoxifen or Evista (or stop taking the medicine early) to reduce breast cancer risk.
If you have a higher-than-average risk of breast cancer, it makes sense to do all that you can to keep your risk as low as it can be. There are lifestyle choices you can make, including:
- maintaining a healthy weight
- exercising regularly at the highest intensity possible
- limiting or avoiding alcohol
- not smoking
- eating a diet that is full of fresh, nutrient-dense foods and low in processed food and foods high in sugar
You and your doctor also may be considering medicine to reduce your risk. Talk to your doctor about your preferences as well as the risks and benefits of each medicine. Together, you can make the best choice for your unique situation.
You can learn more about medicines to reduce risk in high-risk women who haven’t been diagnosed in the Breastcancer.org Hormonal Therapy section.