Factors Associated with Cancer-Related Pain Requiring High-Dose Opioid Use in Palliative Cancer Patients oleh Hidetoshi Sumimoto, Komaki Hayashi, Yuri Kimura, Akihito Nishikawa, Seiko Hattori, Chiaki Hasegawa, Hiroaki Morii, Koji Teramoto, Sachiyo Morita, Yataro Daigo