Oncology Section, Second Department of Internal Medicine, "Hippokration" Hospital, Athens, 11527, Greece. pectasid@otenet.gr. Department of Medical Oncology, "Papageorgiou" Hospital, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. karavasv@auth.gr. Oncology Section, Second Department of Internal Medicine, "Hippokration" Hospital, Athens, 11527, Greece. georgexoinis@gmail.com. Section of Biostatistics, Hellenic Cooperative Oncology Group, Data Office, Athens, Greece. g_gourgioti@hecog.ondsl.gr. Division of Oncology, Department of Medicine, University Hospital, University of Patras Medical School, Patras, Greece. maktom@yahoo.com. Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. graptou@auth.gr. Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. evrettou@med.auth.gr. Third Department of Medical Oncology, "Agii Anargiri" Cancer Hospital, Athens, Greece. josephsgouros@yahoo.co.uk. Third Department of Medical Oncology, "Agii Anargiri" Cancer Hospital, Athens, Greece. epsam@otenet.gr. First Propaedeutic Department of Surgery, "AHEPA" Hospital, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. basdanis@med.auth.gr. Department of Medical Oncology, "Hippokration" Hospital, Athens, Greece. p.papakostas@gmail.com. First Department of Medical Oncology, "Metropolitan" Hospital, Piraeus, Greece. dimmp@otenet.gr. Department of Pathology, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. vkotoula@auth.gr. Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. vkotoula@auth.gr. Division of Oncology, Department of Medicine, University Hospital, University of Patras Medical School, Patras, Greece. kalofonos@upatras.gr. Department of Pathology, University Hospital, University of Patras Medical School, Patras, Greece. cdscopa@med.upatras.gr. Department of Medical Oncology, Ioannina University Hospital, Ioannina, Greece. gpenther@otenet.gr. Department of Medical Oncology, "Papageorgiou" Hospital, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. fountzil@auth.gr. Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Aristotle University of Thessaloniki School of Medicine, Thessaloniki, Greece. fountzil@auth.gr.