For Some Breast Cancer Survivors, Drug May Reduce Treatment-Related Joint Pain
January 4, 2017, by NCI Staff
A drug most commonly used to treat depression may also reduce joint pain in some women being treated for early-stage breast cancer, according to the results of a randomized clinical trial.
After undergoing treatment for early-stage breast cancer, many postmenopausal women take drugs known as aromatase inhibitors to reduce the risk of the cancer returning. These drugs, however, can cause significant pain in women’s joints and muscles.
The clinical trial showed that duloxetine (Cymbalta®), which is approved to treat depression and anxiety as well as fibromyalgia and nerve pain caused by diabetes, provided some relief from pain associated with aromatase inhibitors.
“Joint and muscle pain can lead some patients to discontinue treatment with these life-saving medications,” said N. Lynn Henry, M.D., Ph.D., of the Huntsman Cancer Institute at the University of Utah, who led the study. “Based on our results, duloxetine seems to be an effective drug for some patients who experience this pain.”
Dr. Henry presented findings from the study, which was led by the NCI-supported clinical trials group SWOG, at the San Antonio Breast Cancer Symposium on December 9.
New Strategies Needed
The body uses an enzyme called aromatase to make estrogen. Drugs that block the activity of this enzyme, called aromatase inhibitors, have been found to reduce the risk of cancer returning in postmenopausal women whose breast tumors rely on estrogen to fuel their growth.
But many patients taking these drugs experience pain in the knees, hips, hands, and wrists, which can make everyday tasks difficult. About 20% of patients stop taking aromatase inhibitors due to side effects, according to Dr. Henry. She noted that patients are generally recommended to take aromatase inhibitors for 5 to 10 years, so new strategies for managing the side effects are needed.
For the duloxetine trial, the researchers enrolled 299 women at 43 NCI Community Oncology Research Program (NCORP) sites across the United States. The women had been treated with aromatase inhibitors for early-stage breast cancer and were experiencing joint pain caused by treatment. The women were randomly assigned to receive a 12-week course of duloxetine or a placebo.
Participants completed questionnaires about joint pain, depression, and quality of life at the beginning of the trial, and then again after 2, 6, 12, and 24 weeks. The pain questionnaire used a 0-10 scale; the researchers defined a clinically significant change in average pain as a decrease of 2 or more points from the time a patient entered the study.
Duloxetine and Placebo Reduced Pain
Over the first 12 weeks of the trial, the pain scores of women in the duloxetine group fell an average of 0.82 points more than those of the placebo group. Other measures, including worst pain, joint pain, and stiffness, underwent similar declines.
For the duloxetine group, the average pain score decreased from 5.44 at baseline to 2.91 at 12 weeks. But the average pain score also dropped in the placebo group during the same period, from 5.49 to 3.45. Both reductions were clinically significant, according to the standards of the trial.
The finding of a strong placebo effect in the control group was not entirely unexpected, noted Dr. Henry. Other studies of treatments for pain have reported similar effects, although the reasons are not clear. “This trial demonstrates the need for more research” on responsiveness to placebo, she added.
By 12 weeks, 69% of patients in the duloxetine group and 60% of patients in the placebo group had a 2-point improvement in pain compared to before starting treatment. At 24 weeks, which was 12 weeks after the patients had stopped taking duloxetine or the placebo, the average pain scores were similar for the groups (3.37 in the duloxetine group and 3.42 for the placebo group).
The most common side effects of duloxetine were nausea, fatigue, and dry mouth, which is consistent with other studies involving the drug.
Exploring Multiple Approaches
“These results of the duloxetine study are very promising,” said Ann O’Mara, Ph.D., of NCI’s Division of Cancer Prevention, who was not involved in the study. “Duloxetine is the first drug to show a benefit for this population of patients in a large, randomized clinical trial.”
Dr. O’Mara suggested that patients taking aromatase inhibitors might ultimately need to try multiple approaches to manage their pain. Exercise such as walking and acupuncture are among various strategies that are being studied as ways to reduce pain, she noted.
“Clinicians need to be clear with their patients about the potential side effects of duloxetine, but this drug may help patients decrease their pain and become functional again,” she added.