Kaplan-Meier cumulative incidence estimates of time to first occurrence of four targeted adverse events. Cumulative incidence estimates of (a) cardiac events (any grade), (b) thromboembolic events (any grade), (c) osteoporosis (grade 3) or bone fractures (any grade), and (d) hot flushes or night sweats (any grade) are shown. Letrozole is compared with tamoxifen among the 4,895 patients who were assigned tamoxifen or letrozole monotherapy and who received some trial treatment. All patients had completed treatment (median follow-up of 76 months). AE, adverse event. Reprinted with permission from the Journal of Clinical Oncology . Copyright 2011, American Society of Clinical Oncology.