1. a Unit of Environmental and Occupational Epidemiology, Centre for Study and Cancer Prevention, Florence, Italy
2. b Registro Tumori Azienda Ospedaliera, "Civile-M. P. Arezzo," Ragusa, Italy
3. c National Cancer Institutes in Rome, Genoa, and Milan, Italy
4. d Dipartimento Oncologico-Anatomia Patologica, University of Siena, Italy
5. e Medical Oncology Department, Istituto Oncologico Romagnolo, Forli, Italy
6. f Local Health Unit, Novara, Italy
7. g Agenzia Regionale di Sanità, Florence and Az. Ospedaliera, Verona, Italy
8. h University of Turin, Italy, and Imperial College London, UK