Department of Cancer Epidemiology and Prevention Research, Cancer Control Alberta, Alberta Health Services, Calgary, Alberta, Canada. christine.friedenreich@albertahealthservices.ca. Departments of Oncology and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada. Department of Cancer Epidemiology and Prevention Research, Cancer Control Alberta, Alberta Health Services, Calgary, Alberta, Canada. Department of Epidemiology and Cancer Control, St. Jude Children's Research Hospital, Memphis, Tennessee. Keck School of Medicine, University of Southern California, Los Angeles, California. Cross Cancer Institute, Alberta Health Services, Edmonton, Alberta, Canada. Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.