[1] NCI, Hormonal & Reprod Epidemiol Branch, Div Canc Epidemiol & Genet, NIH,Dept Hlth & Human Serv, Rockville, MD 20892 USA
[2] Yale Univ, Sch Med, New Haven, CT USA
[3] USA, Ctr Hlth Promot & Prevent Med, Silver Spring, MD USA
[4] Walter Reed Army Inst Res, Silver Spring, MD USA