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Expectations May Influence Hormonal Therapy Side Effects, Says Small Study

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After surgery, women diagnosed with hormone-receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence). Hormonal therapy medicines work in two ways:

  • by lowering the amount of estrogen in the body
  • by blocking the action of estrogen on breast cancer cells

There are several types of hormonal therapy medicines. Tamoxifen, a selective estrogen receptor modulator (SERM), is one of the most well-known. Tamoxifen can be used to treat both premenopausal and postmenopausal women. In the early 2000s, the aromatase inhibitors:

  • Arimidex (chemical name: anastrozole)
  • Aromasin (chemical name: exemestane)
  • Femara (chemical name: letrozole)

were shown to be more effective at reducing recurrence risk in postmenopausal women and are now used more often than tamoxifen to treat women who’ve gone through menopause. Aromatase inhibitors aren’t commonly used to reduce recurrence risk in premenopausal women.

Most women take hormonal therapy for 5 to 10 years after breast cancer surgery.

Both tamoxifen and aromatase inhibitors can cause side effects. Tamoxifen may cause hot flashes and increase the risk of blood clots and stroke. Aromatase inhibitors may cause muscle and joint aches and pains. Less common but more severe side effects of aromatase inhibitors are heart problems, osteoporosis, and broken bones. Research has shown that about 25% of women who are prescribed hormonal therapy to reduce the risk of recurrence after surgery either don’t start taking the medicine or stop taking it early, in many cases because of side effects.

A German study suggests that women who expect to have more and more severe side effects before hormonal therapy starts do have worse side effects after 2 years of treatment.

The research was published online on Aug. 22, 2016 by the Annals of Oncology. Read the abstract of “Is it best to expect the worst? Influence of patients’ side-effect expectations on endocrine treatment outcome in a 2-year prospective clinical cohort study.”

The study included 111 women who had surgery to remove hormone-receptor-positive breast cancer and were scheduled to start taking either tamoxifen or an aromatase inhibitor.

Before the women started hormonal therapy, the researchers asked them what they thought about taking hormonal therapy and what kinds of side effects they expected to have. The researchers then asked the women about any side effects they were having 3 months after treatment started and then again 2 years after treatment started.

Before hormonal therapy started:

  • 9 women (8%) expected no side effects
  • 70 women (63%) expected mild side effects
  • 32 women (29%) expected moderate to severe side effects

After 3 months of hormonal therapy treatment, 107 women were still in the study. The 19 women who later dropped out of the study said they had many more side effects than the 88 women who stayed in the study until the 2-year assessment.

The researchers took into account any factors that could make side effects worse, including other medical conditions and symptoms the women were having before treatment started.

Women who expected to have moderate to severe side effects before treatment started were nearly 2 times more likely to have side effects 2 years after hormonal therapy started compared to women who expected no or mild side effects.

Women who expected moderate to severe side effects also had a lower health-related quality of life compared to women who expected no or mild side effects.

Women who stuck with their hormonal therapy treatment plan for 2 years were more likely to have expected no or mild treatment side effects:

  • 87% of women who expected no or mild side effects adhered to treatment
  • 69% of women who expected moderate or severe side effects adhered to treatment

Most of the women had at least one side effect that is common for hormonal therapy:

  • 71% had joint point
  • 53% had weight gain
  • 47% had hot flashes

Still, some women said they had side effects that aren’t directly linked to hormonal therapy, including:

  • back pain (31%)
  • breathing problems (28%)
  • dizziness (26%)

"Our results show that expectations constitute a clinically relevant factor that influences the long-term outcome of hormone therapy," said Dr. Yvonne Nestoriuc, of the University Medical Centre in Hamburg, Germany, who led the study. "Expectations can be modified so as to decrease the burden of long-term side-effects and optimize adherence to preventive anti-cancer treatments in breast cancer survivors.

"Higher negative expectations, formed by patients before the start of their adjuvant therapy, seem to have a pronounced influence on long-term tolerability, especially once they are confirmed by initially high side-effects after three months," she added.

The researchers are now doing a study looking at whether strategies to improve women’s expectations of side effects, such as counseling, can be effective.

"Doctors and patients should not conclude that side effects are psychosomatic based on this one small study," said Brian Wojciechowski, M.D., an oncologist who serves as’s medical adviser. "It does, however, reinforce an idea that is very popular among my patients. Namely, that a positive outlook can be helpful in getting through these difficult treatments."

If you’ve been diagnosed with hormone-receptor-positive breast cancer and will be taking hormonal therapy after surgery and other treatments, it’s very important that you take the medicine for as long as it’s prescribed and at the dose at which it is prescribed. Hormone-receptor-positive breast cancer can come back, and hormonal therapy after surgery reduces that risk -- you must remember that.

Side effects caused by hormonal therapy can be very troublesome for many women. It’s important to talk to your doctor as soon as you start having any side effects, including hot flashes, joint pain, blood clots, trouble sleeping, fatigue, or difficulty concentrating. Don’t wait until the symptoms are intolerable and you have to stop taking the medicine. There are steps you can take to ease these side effects, including switching to a different type of hormonal therapy.

For more information, visit the pages on Staying on Track With Treatment. You can read about why it’s so important to stick to your treatment plan, as well as ways to manage side effects after radiation, chemotherapy, and hormonal therapy. If you’re taking hormonal therapy after surgery now, stick with it as prescribed. If you’re thinking of stopping early, talk to your doctor first. Together, you can find a solution that is best for you.

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