Study to Assess Effect of 8 Wks of Duloxetine Therapy on Breast Cancer Patients With Aromatase-Inhibitor Associated Pain

Aromatase inhibitor (AI) therapy is commonly used for treatment of postmenopausal women with hormone receptor-positive breast cancer. The most common toxicities are arthralgias and myalgias, which can be difficult to manage and necessitate discontinuation of therapy in up to 10% of patients. One potential interventional approach is with a pharmaceutical agent such as duloxetine, which has been shown to be effective for treatment of other types of chronic pain, including fibromyalgia and diabetic neuropathic pain. The primary objective of this pilot study is to determine the proportion of breast cancer patients with AI-associated musculoskeletal symptoms who experience a 30% reduction in average pain score from baseline to 8 weeks due to duloxetine treatment. Participants will be treated with duloxetine for 8 weeks. Questionnaires to evaluate pain, functional status, depression, menopausal symptoms, and sleep difficulties will be administered at baseline and after 2, 4, 6, and 8 weeks of therapy. In addition, 10 milliliters blood of will be drawn from the subjects at baseline for future pharmacogenetic evaluation. If the results of this pilot study suggest that the efficacy of duloxetine therapy is greater than that expected from placebo based on historical controls, then these data will be used to design future prospective, placebo-controlled, randomized trials of treatment with duloxetine in this patient population.