1. From the Medical University, Gdańsk, Poland; Institute of Oncology, Warsaw, Poland; Medical University, Lódź, Poland; Institute of Oncology and Radiology, Belgrade, Yugoslavia; Oncology Research Center, Moscow, Russia; University Hospital for Tumors, Zagreb, Croatia; Latvian Cancer Center, Riga, Latvia; Uzsoki Hospital, Budapest, Hungary; Ichilov Hospital, Tel Aviv, Israel; and Bristol-Myers Squibb Company, Waterloo, Belgium.