1. Department of Obstetrics & Gynecology, Fred Hutchinson Cancer Center, University of Washington, Seattle, WA 98195, USA
2. University of Washington, Center for Biomedical Statistics, Seattle, WA 98195, USA
3. Department of Urology, University of Washington, Seattle, WA 98195, USA
4. Michael Smith Health Research BC, Vancouver, BC, V6H 3X8, Canada
5. Independent Consultant, USA