Evista (chemical name: raloxifene) is a hormonal therapy medicine used to strengthen bones in women with osteoporosis. In September 2007, the U.S. Food and Drug Administration approved using Evista to reduce the risk of breast cancer in postmenopausal women at high risk. Evista also is approved to reduce breast cancer risk in postmenopausal women with osteoporosis.
The RUTH (Raloxifene Use for The Heart) study provides more information on Evista and breast cancer risk reduction in postmenopausal women:
- Postmenopausal women taking Evista were 44% less likely to develop invasive breast cancer than women not taking Evista.
Evista was much more likely to reduce the risk of breast cancers that are hormone-receptor-positive:
- Evista lowered the risk of hormone-receptor-positive invasive breast cancer risk by 55%.
Evista was less likely to reduce the risk of hormone-receptor-negative cancers. More than half of all breast cancers are hormone-receptor-positive.
This study followed more than 10,000 postmenopausal women who either had coronary artery disease or were at high risk for it. The researchers wanted to know if Evista would lower the risk of future heart disease in the women. The researchers also kept track of how many women were diagnosed with invasive breast cancer during the study.
About half the women got Evista and the other half got a placebo. About half of the women were followed for more than 5 1/2 years. The women taking Evista had a lower risk of breast cancer, but Evista didn't lower the risk of heart disease. Evista lowered breast cancer risk most during the first 4 years of treatment. Breast cancer risk was lowered regardless of other factors that can influence risk, such as age, being overweight, family history, and hormone replacement therapy (HRT) use.
It's important to note that only women who already had coronary artery disease or were at high risk for it participated in this study. So the researchers can't say if the results would be the same if women without heart disease or a high risk for it were involved. Still, it's likely that the results would be similar.
Another study, called MORE (Multiple Outcomes of Raloxifene Evaluation), found that Evista reduced the risk of invasive breast cancer by 72% in postmenopausal women. The MORE study included women who didn't have heart disease or a higher risk of heart disease.
Evista is a SERM (selective estrogen receptor modulator) hormonal therapy. 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, Evista interacts with the receptors like estrogen does and strengthens bones. In breast cells, Evista blocks the receptors' interaction with natural estrogen, which reduces estrogen's ability to make cells grow. This is probably why Evista lowers the risk of hormone-receptor-positive breast cancers. Hormone-receptor-negative breast cancers don't have estrogen receptors, so wouldn't be affected by Evista.
Tamoxifen is also a SERM. Tamoxifen is used to lower breast cancer risk in women at high risk and to lower the risk of hormone-receptor-positive breast cancer coming back. Tamoxifen also can improve bone health.
If you're a postmenopausal woman thinking about taking medicine to strengthen your bones, Evista, which is a pill taken by mouth, is one choice you and your doctor can consider. Evista also can reduce your risk of invasive breast cancer. Bisphosphonates are another group of medicines used to strengthen bones. The bisphosphonates include:
- Actonel (chemical name: risedronate)
- Boniva (chemical name: ibandronate)
- Fosamax (chemical name: alendronate)
- Reclast (chemical name: zoledronic acid)
Reclast is given intravenously once a year. The others are pills taken by mouth.
Bisphosphonates strengthen bones better than SERMs, but none of the bisphosphonates have been shown to lower the risk of breast cancer in women who've never been diagnosed.
Both Evista and the bisphosphonates may cause side effects. Evista's side effects may include:
- hot flashes
- joint pain
- leg cramps
- flu-like symptoms
- blood clots deep in the legs
- a blood clot that travels to the lungs (called a pulmonary embolism)
If a woman does develop a blood clot or has a stroke as a side effect of Evista, it may be serious and life-threatening. Some women in the RUTH study experienced these serious side effects.
Side effects of bisphosphonates may include:
- upset stomach
- muscle and joint pain
- esophagus irritation
- osteonecrosis of the jaw (in rare cases)
Some of these side effects can be serious, but the risk of life-threatening side effects is less with bisphosphonates than with Evista.
You and your doctor will need to weigh the risks and benefits of each treatment. You'll also need to consider your unique situation. Do you have a higher than average risk of breast cancer? If so, then Evista may be a good choice for you. Do you have a higher than average risk of breaking a bone? If so, you may opt for the added bone-strengthening ability of a bisphosphonate. Together, you and your doctor can decide what makes the best sense for YOU.
Editor's Note: In July 2013, the American Society of Clinical Oncology put out new guidelines on using hormonal therapy medicines to reduce breast cancer risk in high-risk undiagnosed women. Besides tamoxifen and Evista, the guidelines also recommend that doctors talk to postmenopausal high-risk women about using the aromatase inhibitor Aromasin (chemical name: exemestane) to reduce risk.