Purpose: Although aromatase inhibitors (AIs) prolong survival in post-menopausal breast cancer (BC) patients, AI-associated arthralgia can lead to discontinuation. Obese patients have higher rates of AI arthralgia than non-obese patients, but treatment options are limited. Omega-3 fatty acid (O3-FA) treatment for AI arthralgia has produced mixed results.
Methods: We performed an exploratory analysis of SWOG S0927, a multicenter randomized placebo-controlled trial of O3-FA use for AI arthralgia. Post-menopausal women with stage I-III BC taking an AI were randomized to 24 weeks of O3-FAs or placebo. Brief Pain Inventory (BPI) questionnaires and fasting serum were collected at baseline, 12, and 24 weeks. The BPI assessment included worst pain, average pain, and pain interference scores (range 0-10).
Results: Among the 249 participants, 139 had BMI < 30 kg/m2 (56%) and 110 had BMI ≥ 30 kg/m2 (44%). Among obese patients, O3-FA use was associated with significantly lower BPI worst pain scores at 24 weeks compared with placebo (4.36 vs. 5.70, p = 0.02), whereas among non-obese patients, there was no significant difference in scores between treatment arms (5.27 vs. 4.58, p = 0.28; interaction p = 0.05). Similarly, O3-FA use was associated with lower BPI average pain and pain interference scores at 24 weeks compared with placebo among obese patients, but no significant difference between treatment arms in non-obese patients (interaction p = 0.005 and p = 0.01, respectively).
Conclusions: In obese BC patients, O3-FA use was associated with significantly reduced AI arthralgia compared to placebo.
Keywords: Aromatase inhibitor; Arthralgia; Breast cancer; Obesity; Omega-3 fatty acids.