[1] Tampere Univ Hosp, Dept Gastroenterol & Alimentary Tract Surg, FIN-33521 Tampere, Finland
[2] Univ Tampere, Sch Med, FIN-33014 Tampere, Finland
[3] Tampere Univ Hosp, Dept Dermatol, FIN-33521 Tampere, Finland
[4] Finnish Canc Registry, Inst Stat & Epidemiol Canc Res, FIN-00170 Helsinki, Finland