US Preventive Services Task Force Harold C. Sox, Jr., M.D., Chair Joseph M. Huber Professor and Chair Department of Medicine Dartmouth-Hitchcock Medical Center Lebanon, NH Donald M. Berwick, M.D., M.P.P., Vice Chair Associate Clinical Professor Department of Pediatrics Harvard Medical School Boston, MA Alfred O. Berg, M.D., M.P.H. Professor and Associate Chair Department of Family Medicine University of Washington Seattle, WA Paul S. Frame, M.D. Tri-County Family Medicine Cohocton, NY Clinical Associate Professor Department of Family Medicine University of Rochester School of Medicine and Dentistry Rochester, NY Dennis G. Fryback, Ph.D. Professor of Preventive Medicine and Industrial Engineering Department of Preventive Medicine University of Wisconsin_Madison Madison, WI David A. Grimes, M.D. Professor and Vice Chair Department of Obstetrics, Gynecology and Reproductive Sciences UCSF/San Francisco General Hospital San Francisco, CA Robert S. Lawrence, M.D. Associate Dean for Professional Education and Programs Professor of Health Policy and Management The Johns Hopkins School of Hygiene and Public Health Baltimore, MD Robert B. Wallace, M.D., M.Sc. Professor of Preventive Medicine Director, University of Iowa Cancer Center University of Iowa College of Medicine Iowa City, IA A. Eugene Washington, M.D., M.Sc. Professor and Chief Department of Obstetrics, Gynecology, and Reproductive Sciences UCSF/Mount Zion Medical Center Director, Medical Effectiveness Research Center for Diverse Populations/UCSF San Francisco, CA Modena E.H. Wilson, M.D., M.P.H. Professor of Pediatrics Director, Division of General Pediatrics The Johns Hopkins Children's Center Baltimore, MD Task Force Staff: Carolyn DiGiuseppi, M.D., M.P.H. Editor, Science Writer, and Project Director David Atkins Editor and Science Writer Steven H. Woolf, M.D., M.P.H. Editor and Science Writer Douglas B. Kamerow, M.D., M.P.H. Managing Editor Abigail L. Rose Project Associate