Omega-3 fatty acids significantly reduced aromatase inhibitor (AI)-induced joint pain in obese women with breast cancer, according to a new retrospective analysis of the SWOG S0927 study, a 24-week, randomized, controlled clinical trial that compared omega-3 fatty acids and placebo in patients with AI-related arthralgia. This side effect is more often seen in obese patients with cancer who are taking AIs than in nonobese patients.
These findings were presented at the 2018 Best of ASCO meeting in Chicago by Thomas W. LeBlanc, MD, MHS, FAAHPM, Associate Professor of Medicine, Duke Cancer Institute, Durham, NC.
Although AIs do prolong survival in postmenopausal women with breast cancer, approximately 50% of patients who are taking these drugs experience arthralgia, and many discontinue their use of AIs because of severe pain. There is currently no optimal treatment regimen for this adverse effect, and previous examination of omega-3 fatty acid treatment for AI-induced arthralgia has produced mixed results.
Although the researchers found no benefit to using omega-3 fatty acids in the entire population of women with stage I-III estrogen receptor–positive or progesterone receptor–positive breast cancer in the initial SWOG S0927 randomized study, there is evidence that omega-3 fatty acids are anti-inflammatory and have been shown to reduce systemic inflammation. The researchers also wondered if omega-3 fatty acids could have an impact on AI-induced pain based on the patient’s weight. Therefore, they performed this exploratory post-hoc analysis. They used standard body mass index (BMI) to identify obese patients.
“In overweight patients there may be more stress on the bones, cartilage breakdown due to wear and tear of excessive weight, maybe more stiffness, and likely higher AI drug concentrations,” said Dr LeBlanc. “We know that omega-3 fatty acids are anti-inflammatory and are associated with reduced systemic inflammation, so some folks have wondered if that might also play out on the inflammatory component of AI-related arthralgia. That’s basically the rationale behind doing this secondary analysis,” he noted.
Post-Hoc Analysis Reveals Significant Benefit
The study enrolled 249 female patients with a Brief Pain Inventory worst pain score of 5 or more on a scale of 0 to 10. All participants had been receiving an AI for at least 90 days, and reported pain associated with their use of the drug.
The Brief Pain Inventory scale looks at the intensity and the duration of pain, the overall pain severity, and, in addition, it looks at the impact on a person’s function and their overall well-being, Dr LeBlanc said. “So it’s not just a pain score. It’s a little bit more than that,” he noted.
Participants were divided into 2 groups according to their weight—139 (56%) women had a BMI of <30 kg/m2 and 110 (44%) had a BMI of ≥30 kg/m2.
Among the heavier women—patients with a BMI of ≥30 kg/m2—daily omega-3 fatty acid use significantly reduced arthralgia pain compared with placebo.
Omega-3 use was associated with a 2.89-point decrease in worst pain scores at 24 weeks (the study’s primary end point) compared with only a 1.49-point decrease with placebo use. This group also saw significantly reduced triglyceride levels at 12 weeks compared with placebo.
However, among women with a BMI of <30 kg/m2, the pain scores and triglyceride levels did not significantly differ between the omega-3 fatty acid and placebo groups.
“For each of the following areas—worst pain, average pain, and pain interference—there was a significant improvement in the obese patients compared to placebo,” suggested Dr LeBlanc. “You don’t see that in the nonobese patients. So ultimately, this post-hoc analysis showed us a relevant subgroup where a patient with AI-related arthralgia might be more likely to respond to, and perhaps meaningfully benefit from, omega-3 fatty acid supplementation,” he added.
If the study results are confirmed, omega-3 fatty acid use may lead to improved adherence to AIs in this subset of obese patients with breast cancer, according to the investigators.
“This is an effective, well-tolerated, inexpensive and widely available treatment option for the management of a hard-to-treat symptom in individuals who are obese on AI therapy,” Dr LeBlanc continued.
“So this is a potentially practice-changing insight from the Patient and Survivor Care track of this year’s ASCO annual meeting,” he added.
This study was originally presented at ASCO 2018 by Sherry Shen, MD, Resident, Columbia University Medical Center, New York City.