[1] Dongguk Univ, Dept Family Med, Ilsan Hosp, Goyang Si, South Korea
[2] Tohoku Univ, Dept Palliat Med, Sch Med, Sendai, Miyagi, Japan
[3] Takeda Gen Hosp, Dept Palliat Med, Aizu Wakamatsu, Fukushima, Japan
[4] Dongguk Univ, Dept Med, Med Sch, Pildong 1-30, Seoul, South Korea
[5] Dongguk Univ Seoul, Dept Stat, Seoul, South Korea
[6] Seoul Natl Univ, Bundang Hosp, Dept Internal Med, Coll Med,Div Hematol & Med Oncol, Seongnam Si, South Korea
[7] CHA Univ, Bundang Med Ctr, Div Med Oncol, Seongnam Si, South Korea
[8] Yonsei Univ, Yonsei Canc Ctr, Dept Internal Med, Div Med Oncol,Coll Med, Seoul, South Korea