[1] Hokkaido Univ, Sch Med, Dept Med 1, Kita Ku, Sapporo, Hokkaido 0608638, Japan
[2] Natl Hosp Org Hokkaido Canc Ctr, Dept Pulm Dis, Sapporo, Hokkaido, Japan
[3] Fukushima Med Univ, Sch Med, Dept Pulm Med, Fukushima, Japan
[4] Natl Hosp Org Dohoku Natl Hosp, Dept Resp Med, Asahikawa, Hokkaido, Japan
[5] Hokkaido Social Insurance Hosp, Dept Internal Med, Sect Resp Dis, Sapporo, Hokkaido, Japan
[6] KKR Sapporo Med Ctr, Dept Med Oncol, Sapporo, Hokkaido, Japan
[7] Hokkaido Chuo Rosai Hosp, Dept Med, Iwamizawa, Japan