1. Department of Surgery, University Hospital Groningen, PO Box 30.001, 9700 RB. Groningen, The Netherlands
2. Department of Medical Oncology, University Hospital Groningen, PO Box 30.001, 9700 RB. Groningen, The Netherlands
3. Department of Pathology, University Hospital Groningen, PO Box 30.001, 9700 RB. Groningen, The Netherlands