Both Fish Oil and Placebo Ease Joint Pain in Women Taking 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. In 2005, 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.

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.

A study found that taking fish oil omega-3 fatty acids supplements eased joint pain in women diagnosed with breast cancer taking an aromatase inhibitor. Still, women who took a placebo (a fake pill that looked just like the fish oil supplement) also got relief from joint pain.

The study was published online on May 4, 2015 by the Journal of Clinical Oncology. Read the abstract of “Randomized Multicenter Placebo-Controlled Trial of Omega-3 Fatty Acids for the Control of Aromatase Inhibitor-Induced Musculoskeletal Pain: SWOG S0927.”

The study was led by Dawn Hershman, M.D., M.S., assistant professor of medicine at the Columbia University Medical Center and director of the Clinical Breast Oncology Program at New York-Presbyterian Hospital. Dr. Hershman is a member of the Breastcancer.org Professional Advisory Board.

In the study, researchers randomly assigned 249 women diagnosed with early-stage breast cancer who were being treated with an aromatase inhibitor and who were having severe joint pain to one of two supplements daily for 24 weeks:

  • 3.3 grams of fish oil omega-3 fatty acids (122 women)
  • placebo pill that looked just like the fish oil pill but contained soybean and corn oil (127 women)

Omega-3 fatty acids are known to reduce inflammation in the body and have been studied as possible treatments for rheumatoid arthritis and other inflammatory conditions for many years.

The women in the study were about 59 years old and 87% of them were white.

The researchers assessed the women’s joint pain before the study started and then at 6, 12, and 24 weeks after the study started. The researchers also tested the women’s blood cholesterol and triglyceride levels.

Compared to their joint pain scores before the study started, the women who took the fish oil supplement had their pain score go down by:

  • 1.74 points at week 12
  • 2.22 points at week 24

Similarly, compared to their joint pain scores before the study started, the women who took the placebo had their pain scores go down by:

  • 1.49 points at week 12
  • 1.81 points at week 24

When the researchers accounted for other factors that might affect the women’s pain such as osteoarthritis and whether they had been treated with a taxane chemotherapy medicine (taxanes also cause muscle and joint pain), they found that the fish oil and the placebo eased pain the same amount.

Women who took the fish oil supplement had lower triglyceride levels after 24 weeks. There was no change in the triglyceride levels of the women who took the placebo.

The researchers aren’t sure why women who took the placebo got the same benefits as the women who took the fish oil supplement. It could be that the women’s joint pain naturally eased over time, which happens in many cases. It’s also possible that the corn and soy oil in the placebo pill helped ease the women’s joint pain. The researchers also wondered if some of the women in the placebo arm were independently taking fish oil supplements.

Other studies looking at exercise and acupuncture to ease joint pain caused by aromatase inhibitors found that the women who got placebos in those studies got no joint pain relief.

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 a fish oil omega-3 fatty acids supplement is right for you and your unique situation.

Before you start taking fish oil or any other supplement, talk to your doctor. Supplements can’t always be taken safely along with prescription medicines. Some supplements can change the way medicines and radiation work in your body and may make the treatments less effective. So it’s very important that you talk to your doctor about any supplements you’re thinking about taking.



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