P2-17-09: A Prospective Assessment of Loss of Grip Strength by Baseline BMI in Breast Cancer Patients Receiving Adjuvant Aromatase Inhibitors or Tamoxifen.

Abstract

Abstract Background The 3rd generation aromatase inhibitors (AIs) induce or enhance musculoskeletal problems. Underlying mechanisms are probably multiple, but remain unknown. We have previously reported that loss of grip strength together with tenosynovial abnormalities are more important in AI- than in tamoxifen-users (Morales et al, JCO 2008) and that musculoskeletal changes in AI-users are more pronounced in women with extremes in baseline BMI (Lintermans et al, Ann Oncol 2011) We here report preliminary results from a larger population and plan to validate findings in patients from University of Michigan. Patients and methods In this prospective observational study, postmenopausal early breast cancer patients scheduled to start adjuvant hormonal therapy with any of the third generation AIs or tamoxifen were recruited. After providing informed consent, a functional assessment test of grip strength was performed with a modified sphygmomanometer. Re-evaluation was done after 3, 6 and 12 months of therapy. BMI and waist to hip ratio (WHR) were assessed and a rheumatological questionnaire was completed at each visit. Results Ninety-four (79 AI; 15 tamoxifen) of the planned 200 patients were included in this preliminary study. 18% of AI-users discontinued their treatment due to musculoskeletal symptoms compared with none of the tamoxifen-users. 62% of patients on AI and 35% of tamoxifen patients complained of new or worsened joint pain. Table 1 shows the proportion of patients that attribute their complaints to their endocrine therapy. Grip strength significantly decreased over time (p=0.03), with patients under AI treatment having a larger loss of grip strength than patients under tamoxifen treatment (p=0.04). We confirm our previously reported results on the shape of the curve “BMI AI-induced loss of grip strength”. Years past menopause and age showed a significant effect on grip strength (p<0.001 and p=0.0007, respectively), whereas no significant relationship was found between WHR with grip strength or joint pain. Detailed results will be presented. Conclusion Our preliminary results confirm that a majority of patients treated with an AI experience musculoskeletal problems, which are considered due to the therapy by most patients. Grip strength decreased over time, with a significantly larger loss of grip strength in the AI-users compared with the tamoxifen-users. AI-induced loss of grip strength and baseline BMI showed an inverted U-shaped association, although differences between quartiles were small. Further results should be awaited as this is only a preliminary analysis. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-17-09.