Compliance and arthralgias in clinical therapy (COMPACT): Assessment of the incidence of arthralgia, therapy costs, and compliance in the first year of adjuvant anastrozole.

e11040^ Background: Aromatase Inhibitors (AI) are well established as adjuvant endocrine treatment for postmenopausal women with HR+ early breast cancer (EBC). However, clinical trial data show higher frequently of arthralgia with AI than tamoxifen. As arthralgia may be greatly influencing compliance to adjuvant therapy, we designed a prospective trial to collect real world data on the effects of AI-associated arthralgia on patient compliance, patient outcomes and treatment costs of arthralgia. Methods: COMPACT is an open, prospective non-interventional study (NCT00857012) assessing the incidence of arthralgia, therapy costs, and compliance within the first year of adjuvant anastrozole (ANA) therapy in postmenopausal patients with HR+ EBC. Patients on adjuvant ANA for 3-6 months were enrolled and stratified by initial adjuvant ANA or switch from tamoxifen. All patients receive regular standardized information about breast cancer from baseline to week 20 to support treatment compliance. Data on demographic...