The effect of tamoxifen (T) or exemestane (E) on bone mineral density (BMD) after 1 year of adjuvant treatment of postmenopausal women with early breast cancer

610 Background: Postmenopausal women are at risk for bone loss with the average anticipated loss of 1–2% per year. In this substudy of a larger ongoing adjuvant hormonal trial of T vs. E, we evaluated the effect of 1-year of adjuvant hormonal therapy on BMD. Methods: 625 women have entered this substudy. 182 women have now completed 1-year of blinded therapy with T or E at standard doses and have undergone baseline and 1-year BMD of the hip and spine measured by bone densitometry. No patient was receiving prescription bone agents. Mean differences between baseline and 1-year were tested within the treatment arms using paired t-tests. Results were reported as standardized T-scores to counteract the effect of underlying differences in the parameters of the 2 arms. Results: 103 women treated with T and 79 with E were evaluable with a median age of 64 years (range, 43–87). Initial BMD was similar for both arms. Baseline and 1-year data are shown in the table. Two fractures have been observed in the T arm, but...