[1] Leiden Univ, Med Ctr, Surg, Leiden, Netherlands
[2] Belgian Canc Registry, Res, Brussels, Belgium
[3] Aarhus Univ Hosp, Surg, DK-8000 Aarhus, Denmark
[4] Natl Canc Registry Ireland, Res, Cork, Ireland
[5] Karolinska Inst, Moleculare Med & Surg, Stockholm, Sweden
[6] Uppsala Univ, Surg Sci, Uppsala, Sweden
[7] Catharina Hosp, Surg, Eindhoven, Netherlands
[8] Comprehens Canc Ctr Netherlands, Res, Utrecht, Netherlands