1. From the Vanderbilt Epidemiology Center (QD, MJS, QC, and WZ) and the Division of Gastroenterology, Hepatology and Nutrition (RMN and WES), Department of Medicine, and the Department of Biostatistics (ML and YS), Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN; the Department of Psychology, College of Arts and Sciences, Vanderbilt University, Nashville, TN