Aromatase inhibitors are hormonal therapy medicines used to treat breast cancer and help stop breast cancer from coming back (recurrence) in postmenopausal women.
Research has shown that the aromatase inhibitor Aromasin (chemical name: exemestane) also can reduce the risk of first-time hormone-receptor-positive breast cancer in postmenopausal women at high risk for the disease.
Still, Aromasin is known to cause side effects, and some women stop taking the medicine because of severe side effects, including muscle and joint pain, hot flashes, and other menopausal symptoms.
A study suggests that women whose menopausal symptoms get worse after starting preventive Aromasin are more likely to stop taking the preventive medicine early.
The study was published in the Feb. 20, 2017 issue of the Journal of Clinical Oncology. Read “Factors Associated With Early Discontinuation of Study Treatment in the Mammary Prevention.3 Breast Cancer Chemoprevention Trial.”
Arimidex (chemical name: anastrozole) another aromatase inhibitor, also has been shown to reduce the risk of first-time hormone-receptor-positive breast cancer in postmenopausal women at high risk. Tamoxifen and Evista (chemical name: raloxifene), both SERMs (selective estrogen receptor modulators), another type of hormonal therapy medicine, also have been shown to reduce the risk of hormone-receptor-positive breast cancer in high-risk postmenopausal women. Tamoxifen also reduces the risk of hormone-receptor-positive breast cancer in high-risk premenopausal women.
Doctors call giving medicine to reduce the risk of a disease a person hasn’t been diagnosed with “prophylactic” or “preventive.”
While Aromasin and Arimidex haven’t been approved by the U.S. Food and Drug Administration to be used preventively for breast cancer, many doctors consider them good alternatives to tamoxifen or Evista. 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 Aromasin to reduce risk.
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.
Aromatase inhibitors work by stopping the body from producing estrogen, which limits the amount of estrogen available to stimulate hormone-receptor-positive breast cancer cells to grow.
The large MAP.3 trial was designed to see if Aromasin could reduce breast cancer risk in postmenopausal women at high risk for breast cancer who had never been diagnosed with the disease. Results released in February 2012 showed that Aromasin was effective. Results released in April 2014 found that Aromasin had only a slight effect on quality of life for most women taking the medicine preventively.
In this latest report of MAP.3 results, the researchers wanted to know why some women in the study stopped treatment early.
In the MAP.3 trial, the researchers randomly split the approximately 4,500 high-risk, postmenopausal women in the study into two groups. One group was assigned to take Aromasin once a day for 5 years; the other group took a placebo (a sugar or “dummy” pill) once a day for 5 years.
Before the study started and again 6 months after the study began, the women filled out the Menopause-Specific Quality of Life Questionnaire (MENQOL). MENQOL is a standardized research tool used to assess the severity of menopausal symptoms. MENQOL asks about four types of symptoms: vasomotor, psychosocial, physical, and sexual.
Vasomotor symptoms are:
- hot flashes
- night sweats
Psychosocial symptoms are:
- dissatisfaction with personal life
- feeling anxious or nervous
- having memory problems
- feeling depressed or blue
- being impatient with other people
- wanting to be alone
Physical symptoms are:
- gas pain or flatulence
- muscle and joint pain
- feeling tired or worn out
- sleeping problems
- head or neck aches
- loss of strength
- loss of energy
- dry skin
- weight gain
- growth of facial hair
- changes in skin texture or tone
- feeling bloated
- low back pain
- feeling the need to urinate more often
- accidentally urinating when laughing or coughing
Sexual symptoms are:
- changes in sexual desire
- vaginal dryness
- avoiding intimacy
Any women in the study who stopped treatment within 1 year of the study’s start was considered to have stopped treatment early. The researchers didn’t include women who stopped treatment because they were diagnosed with breast cancer. Overall, 4,501 women were included in this analysis of the study.
By the end of the first year, 724 women had stopped treatment:
- 19% of women in the Aromasin groups stopped early
- 13% of women in the placebo group stopped early
According to results from MENQOL, 1,000 women in the study (24%) had their menopausal symptoms get worse. Within the first 6 months of the study:
- 35% of the women had worse vasomotor symptoms
- 27% of the women had worse psychosocial symptoms
- 28% of the women had worse physical symptoms
- 19% of the women had worse sexual symptoms
The researchers found that women who had their menopausal symptoms get worse during the first 6 months of the study were 76% more likely to stop treatment early compared to women who didn’t have their symptoms get worse in the first 6 months.
The researchers then looked at other factors that might have contributed to a woman stopping treatment early:
- Women assigned to get Aromasin were 59% more likely to stop treatment early than women assigned to get the placebo.
- Women who previously smoked were 22% more likely to stop treatment early compared to women who never smoked.
- Current smokers were 39% more likely to stop treatment early compared to women who never smoked.
The researchers concluded that no matter which treatment the women were assigned to receive -- Aromasin or placebo -- women who had their menopausal symptoms get worse during the study were much more likely to stop treatment early than women who didn’t have their symptoms get worse.
“From a clinical perspective, the results…suggest that attention to such menopausal symptoms, even when not caused by the aromatase inhibitor, may improve quality of life and medication adherence as well,” the researchers wrote.
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 foods 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 you’re considering. If you’re already taking hormonal therapy preventively and are having unacceptable side effects, talk to your doctor. There are medicines and complementary medicine techniques, such as acupuncture, that can help ease side effects. You also may be able to switch to a different hormonal therapy 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.
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