1. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland. 1
2. Tobacco Control Research Branch, Division of Cancer Control and Population Sciences, National Cancer Institute, Rockville, Maryland. 2
3. Krieger School of Arts and Sciences, The Johns Hopkins University, Baltimore, Maryland. 3
4. Clinical Cancer Epidemiology Team, The Institute of Cancer Research, London, United Kingdom. 4