Footnotes

• Contributors PLH designed this study. NH and HSu provided technical and data support. HSung, PLH and HHY analysed and interpreted the data. HSung and PLH wrote the manuscript. HSung, PRT and PLH revised the manuscript critically for important intellectual content.

• Funding This research was funded by Intramural Research Program of the National Institutes of Health, the National Cancer Institute, the Division of Cancer Epidemiology and Genetics, and the Center for Cancer Research.

• Competing interests None declared.

• Patient consent Obtained.

• Ethics approval National Cancer Institute Special Studies IRB.

• Provenance and peer review Not commissioned; internally peer reviewed.