1. From the Departments of Epidemiology, Breast Medical Oncology, Clinical Cancer Genetics, and Molecular Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston; Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas; Cancer Therapy and Research Center, San Antonio, TX; and Global Pharmacovigilance and Epidemiology, Aventis Pharmaceuticals Inc, Bridgewater, NJ.