BACKGROUND	In the Postmenopausal Evaluation and Risk-Reduction with Lasofoxifene ( PEARL ) trial , lasofoxifene was shown to reduce the risk of estrogen receptor-positive ( ER + ) breast cancer , nonvertebral and vertebral fractures , coronary artery disease , and stroke , but the effects on total breast cancer ( invasive and ductal carcinoma in situ , ER + and estrogen receptor-negative [ ER - ] ) and ER + invasive breast cancer are unknown .\