作者单位:Registre Neuchatelois des Tumeurs, Av. des Cadolles 7, Neuchatel, Switzerland[1]Cancer Epidemiology Unit and Registre Vaudois des Tumeurs, Institute of Social and Preventive[2]Department of Epidemiology, Istituto di Ricerche Farmacologiche Mario Negri, Via La Masa 19, Milan[3]