1 Department of Surgery, Medical University of Vienna, A-1090 Vienna, Austria; Comprehensive Cancer Centre, Medical University of Vienna, A-1090 Vienna, Austria. Electronic address: michael.gnant@meduniwien.ac.at.
2 Comprehensive Cancer Centre, Medical University of Vienna, A-1090 Vienna, Austria; Department of Gynaecology and Obstetrics, Medical University of Vienna, A-1090 Vienna, Austria.
3 Department of Statistics, Austrian Breast & Colorectal Cancer Study Group, Vienna, Austria.