A Prospective Assessment of Loss of Grip Strength by Baseline BMI in Breast Cancer Patients Receiving Adjuvant Third-generation Aromatase Inhibitors and Tamoxifen

Early stage hormone receptor positive breast cancer is typically treated with adjuvant endocrine therapy in order to decrease risk of breast cancer recurrence and to improve overall survival from the disease. Typical agents used for treatment include tamoxifen and the aromatase inhibitors. In postmenopausal women, aromatase inhibitor therapy is increasingly common because it is associated with fewer long-term serious toxicities compared to tamoxifen. However, aromatase inhibitors cause arthralgias in 40-50% of patients, which can influence adherence to therapy and can lead to treatment discontinuation in a minority of cases. The mechanism underlying development of this toxicity remains unclear, and predictors of who will develop these symptoms remain undefined. Initial reports suggest that grip strength decreases during aromatase inhibitor therapy, and that body-mass index may influence development of this symptom. Therefore, this longitudinal study has been developed to determine change in grip strength over time in women treated with aromatase inhibitors and tamoxifen, as well as to identify potential associations between change in grip strength and BMI. Patient self-reported symptoms will also be collected. A total of 115 women with early stage breast cancer who are initiating therapy with either an aromatase inhibitor or tamoxifen will be enrolled.