[1] Mario Negri Inst Pharmacol Res, Lab Epidemiol, I-20157 Milan, Italy
[2] Ctr Riferimento Oncol, Unita Epidemiol & Biostat, I-33081 Aviano, PN, Italy
[3] Ist Tumori Fdn Pascale, Serv Epidemiol, Naples, Italy
[4] Int Agcy Res Canc, F-69372 Lyon, France
[5] Univ Milan, Ist Stat Med & Biometria, I-20122 Milan, Italy