1. Department of Epidemiology; IRCCS-Istituto di Ricerche Farmacologiche Mario Negri; Milan Italy
2. Department of Statistics and Quantitative Methods; University of Milan-Bicocca; Milan Italy
3. Division of Epidemiology and Biostatistics; European Institute of Oncology; Milan Italy
4. Unit of Epidemiology and Biostatistics; CRO Aviano National Cancer Institute; IRCCS; Aviano Italy
5. Institute for Social and Preventive Medicine; University of Lausanne; Lausanne Switzerland
6. Department of Clinical Sciences and Community Health; University of Milan; Milan Italy