Cymbalta Eases Joint Pain From Aromatase Inhibitors

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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. Another type of hormonal therapy, the aromatase inhibitors:

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

have been shown to be more effective at reducing recurrence risk in postmenopausal women and are 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.

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 breast cancer surgery either don’t start taking the medicine or stop taking it early. In many cases, this is because of side effects.

If doctors can find a way to ease these side effects, more women might stick to their treatment plans.

A study has found that the antidepressant Cymbalta (chemical name: duloxetine) can ease joint pain in women diagnosed with early-stage, hormone-receptor-positive breast cancer who are taking an aromatase inhibitor after surgery.

The research was published online on Nov. 14, 2017 by the Journal of Clinical Oncology. Read the abstract of “Randomized, Multicenter, Placebo-Controlled Clinical Trial of Duloxetine Versus Placebo for Aromatase Inhibitor-Associated Arthralgias in Early-Stage Breast Cancer: SWOG S1202.”

The study included 299 postmenopausal women who had been diagnosed with early-stage, hormone-receptor-positive breast cancer. The women had all been taking an aromatase inhibitor for at least 3 weeks, and all of them reported average joint pain rated as 4 or higher on a 0- to 10-point scale. The women enrolled in the study between May 2013 and October 2015.

The women were randomly assigned to receive one of two treatments for joint pain:

  • 127 women took Cymbalta: one 30-mg capsule daily for 1 week, then two 30-mg capsules daily for 11 weeks, then one 30-mg capsule daily for the last week
  • 128 women took placebo: a dummy capsule that looked just like Cymbalta and was taken on the same schedule

The researchers assessed the women’s joint pain 2 weeks, 6 weeks, and 12 weeks after starting Cymbalta or placebo, and then again 24 weeks after the study started (11 weeks after completing Cymbalta or placebo treatment).

When the study began, about 75% of the women rated their joint pain as 4 to 6 on the 10-point scale.

The researchers found that at the 2-week, 6-week, and 12-week assessments, women taking Cymbalta had greater decreases in joint pain than women taking the placebo. By the 24-week assessment, joint pain reduction was the about the same for the two groups.

Like most medicines, Cymbalta can cause side effects. In this study, more women taking Cymbalta (78%) said they had moderate to mild side effects compared to women taking the placebo (50%). None of the women in the study reported severe side effects. The most common side effects were the same for both treatment groups:

  • fatigue
  • nausea
  • dry mouth
  • headache

While the side effects of hormonal therapy can be troubling, they’re overshadowed by the reality that hormone-receptor-positive breast cancer can come back. Hormonal therapy after surgery reduces that risk. If you’ve been prescribed hormonal therapy after surgery, you must remember this.

There are steps you can take to get rid of any obstacles stopping you from doing all you can to lower your recurrence risk. If side effects are a major problem for you, talk to your doctor about ways to manage them. You also may be able to switch to a different hormonal therapy.

If you’re currently taking an aromatase inhibitor and having joint pain, you may want to talk to your doctor about this study and ask if taking Cymbalta is right for you and your unique situation.

Other studies have found that taking a fish oil supplement, acupuncture, massage, chiropractic therapy, and other complementary medicine techniques can help ease joint pain caused by aromatase inhibitors.

Before you start taking any supplement or try a complementary medicine technique, it’s a good idea to talk to your doctor and discuss all the risks and benefits of each supplement or technique. Together, you can develop a strategy to ease side effects and help you stick to your treatment plan.

For more information on managing bone pain, visit the Breastcancer.org Bone and Joint Pain page in the Treatment Side Effects section.


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