Pilot study of duloxetine for treatment of aromatase inhibitor‐associated musculoskeletal symptoms

Abstract

BACKGROUND: Approximately 50% of postmenopausal women with hormone receptor‐positive early stage breast cancer treated with an aromatase inhibitor (AI) develop musculoskeletal symptoms. Standard analgesics are relatively ineffective. Duloxetine is a serotonin norepinephrine reuptake inhibitor with proven efficacy for treatment of multiple chronic pain states. The authors investigated the hypothesis that duloxetine is efficacious for treatment of AI‐associated musculoskeletal symptoms. METHODS: The authors performed a single‐arm, open‐label phase 2 study of duloxetine in postmenopausal women with breast cancer who developed new or worsening pain after treatment with an AI for at least 2 weeks. Patients were treated with duloxetine for 8 weeks (30 mg for 7 days, then 60 mg daily). The primary endpoint was a 30% decrease in average pain score over 8 weeks, and secondary outcomes included change in average and worst pain, pain interference, depression, sleep quality, and hot flashes. Statistical analysis was done with t tests for paired data. RESULTS: Twenty‐one of 29 evaluable patients (72.4%) achieved at least a 30% decrease in average pain, and 18 of 23 patients (78.3%) who completed protocol‐directed treatment continued duloxetine. The mean percentage reduction in average pain severity between baseline and 8 weeks was 60.9% (95% confidence interval [CI], 48.6%‐73.1%), and in maximum pain severity it was 59.9% (95% CI, 47.0‐72.7%). The most common adverse events were grade 1 or 2 fatigue, xerostomia, nausea, and headache. CONCLUSIONS: Duloxetine appears to be effective and well tolerated for treatment of AI‐associated musculoskeletal symptoms. Future randomized, placebo‐controlled studies are warranted. Cancer 2011;. © 2011 American Cancer Society. Bothersome musculoskeletal symptoms affect about half of women with early stage breast cancer treated with aromatase inhibitors. In this pilot clinical trial, treatment with duloxetine appeared to significantly improve pain and functioning, and was relatively well tolerated.