Abstract P6-09-08: <u>COMP</u>liance and <u>A</u>rthralgia in <u>C</u>linical <u>T</u>herapy: The COMPACT trial, assessing the incidence of arthralgia, therapy costs and compliance within the first year of adjuvant anastrozole therapy
Authors: N Harbeck, M Blettner, WW Bolten, H-J Hindenburg, C Jackisch, P Klein, K König, R Kreienberg, W Rief, D Wallwiener, S Zaun, P Hadji
Journal: Cancer Research (2012)

Abstract Background: Aromatase Inhibitors (AI) are well established as adjuvant treatment for postmenopausal (PMP) women with hormone receptor positive (HR+) early breast cancer (EBC). However, phase III clinical trials have reported higher rates of arthralgia associated with AI than tamoxifen. This study aims to collect real world data on the effects of AI-associated arthralgia on patient compliance, patient outcomes and on treatment of arthralgia. Methods: COMPACT is an open, prospective, non-interventional, non-randomized study (NCT00857012) run in Germany. PMP women with HR+ EBC who had been on adjuvant anastrozole (ANA) for 3–6 months were enrolled and stratified by initial adjuvant ANA or switch from tamoxifen. All patients received regular standardized information about breast cancer from baseline to week 20 to support treatment compliance. Data on demographics, arthralgia, related therapies, other side effects and QoL were collected at baseline, 3, 6 and 9 months. Primary endpoints are scaled data on arthralgia and compliance within the first year of ANA therapy. Secondary endpoints include incidence of arthralgia, therapy costs, reasons for non-compliance, and influence of arthralgia on clinical outcome. Results: Between Apr 2009 and Mar 2011, 2313 patients were enrolled, 2007 on upfront ANA and 306 on switch from tamoxifen. The mean age at baseline was 64.5 years, mean BMI 27.7. Only 17.0% of patients had received HRT prior to their EBC. At baseline, 41.9% reported symptoms relating to skeleton or musculature. 12.0% reported arthralgia existing prior to ANA treatment and 13.2% stated a worsening of pre-existing arthralgia or new arthralgia after starting ANA. Predictors for non-adherence to AI therapy were former non-adherence, general symptom load on the side effect scale GASE, and low benefit expectation at treatment start. Risk of arthralgia was related to BMI (lowest for patients with BMI ≤24.1 kg/m2, highest with BMI &amp;gt;30.5 kg/m2 at all time points; OR&amp;gt;1) and upfront therapy (switch patients had a reduced risk of 68% at 6 and 61% at 9 months compared to patients with ANA upfront, p = 0.002). Patients with prior chemotherapy had lower rates of arthralgia before start of ANA (10.4% vs 13.3%, p = 0.036) but higher rates after the start of ANA and before study start (27.0% vs 22.5%, p = 0.013). Patients with arthralgia showed higher compliance rates at all time points (p &amp;lt; 0.001). Conclusion: COMPACT identified arthralgia and musculoskeletal symptoms as common complaints in PMP women with EBC. ANA treatment both increased the number of women with such symptoms and aggravated these in some patients. Higher BMI and upfront AI predicted for risk of AI associated arthralgia. However, COMPACT also showed that AI-associated arthralgia did not lead to non-compliance in most patients. This data may help to better understand compliance issues with adjuvant AI treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-09-08.