Joint pain is included among the common side effects patients list for the treatment of their breast cancer with aromatase inhibitors or AIs such as anastrozole (Arimidex?;AstraZeneca), letrozole (Femara?; Novartis), and exemestane (Aromasin?; Pfizer). Now a new study presented at the San Antonio Breast Cancer Symposium (SABCS), being held December 10?14, 2013, in San Antonio, Texas, shows that breast cancer survivors taking these type of drugs experienced a reduction in joint pain if they exercised while on treatment.

Five years of treatment with aromatase inhibitors or AIs after surgery or other primary treatment is recommended for postmenopausal women diagnosed with stages 1-3 hormone receptor-positive breast cancers, which account for nearly 70% of all newly diagnosed breast cancer cases. Up to 50% of patients on AIs report experiencing arthralgia, or joint pain and stiffness. This side effect is the most common reason for poor or non-adherence or patients stop taking the drug entirely.

?Aromatase inhibitors play an important role in the effective treatment of hormone receptor-positive breast cancer,? explained Melinda L. Irwin, Ph.D., M.P.H., associate professor of chronic disease epidemiology at the Yale School of Public Health and co-leader of the Cancer Prevention and Control Research Program at the Yale Cancer Center. ?Unfortunately, many patients discontinue the drug because of its unpleasant side effects. In this study, we discovered that exercise improves joint pain, the most common side effect of AI use. These results are a promising first step in developing clinical interventions that can improve AI-associated joint pain and, in turn, AI adherence, breast cancer survival, and quality of life.

Many patients discontinue the drug because of its unpleasant side effects…

Exercise program
In this randomized trial, Irwin and colleagues investigated the impact of a yearlong exercise program compared with usual care on women who were taking AIs and experiencing joint pain. Measures of worst pain, pain severity, and pain interference dropped 20% among participants who were assigned to the exercise program, compared with modest increases or no change in joint pain among participants who were assigned to usual care. Exercisers experienced these improvements regardless of age; disease stage; whether they received chemotherapy, radiation, or both; and how long they had been taking AIs.

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Dose-response effect
The researchers also observed a dose-response effect: Women who attended at least 80% of the supervised exercise sessions experienced a 25% decrease in worst pain scores, while women who attended fewer than 80% of the supervised exercise sessions experienced a 14% decrease. Similarly, women who experienced a 5% increase in cardiorespiratory fitness had a 29% decrease in worst pain scores, compared with a 7% decrease in worst pain scores among women who experienced a smaller increase in cardiorespiratory fitness.

The 121 study participants were postmenopausal women diagnosed with stages 1-3 hormone receptor-positive breast cancers who were taking an AI. All reported at least mild joint pain and were not exercising at enrollment, but were physically able to exercise.

Sixty-one participants were randomly assigned to an exercise program that entailed twice-weekly supervised resistance and strength training sessions and 150 minutes per week of at least moderate-intensity aerobic exercise, such as brisk walking. This exercise prescription is the current recommendation for healthy adults and cancer survivors.

“We found that participating in an exercise intervention led to clinically meaningful improvements in AI-induced arthralgias in breast cancer survivors experiencing moderate joint pain. The intervention also induced favorable changes in body weight and cardiorespiratory fitness, factors that may be linked to incidence and severity of AI-induced arthralgias,” Irwin concluded.

Ongoing studies
The researcher agree that further studies are needed to determine whether exercise leads to increased AI adherence and possibly better outcomes in women with breast cancer. Hence, Irwin and colleagues will next examine in more detail the mechanisms that may be influencing the effect of exercise on AI-associated joint pain, including body weight, inflammation, and muscular strength, as well as whether improvements in joint pain occurred at the beginning, middle, or end of the yearlong intervention.

This study was funded by the National Cancer Institute. Irwin declares no conflicts of interest.

For more information
[1] Irwin ML, Cartmel B, Gross C, Ercolano E, Fiellin M, Capozza S, Rothbard M, et al. Randomized trial of exercise vs. usual care on aromatase inhibitor-associated arthralgias in women with breast cancer: The hormones and physical exercise (HOPE) study. Publication Number: S3-03. Presented by Melinda L. Irwin, Ph.D., M.P.H.

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