1. Department of Medical Oncology, West German Cancer Center, University Hospital Essen, 45147 Essen
2. West German Cancer Center, University Hospital Essen, University of Duisburg-Essen, Essen
3. Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen, University of Duisburg-Essen, 45147 Essen
4. Department of Palliative Medicine, West German Cancer Center, University Hospital Essen, 45147 Essen