[1] Chulalongkorn Univ, Fac Med, Dept Med, Gastrointestinal Endoscopy Excellent Ctr, Bangkok 10330, Thailand
[2] Chulalongkorn Univ, Fac Med, Dept Surg, Bangkok 10330, Thailand
[3] Chulalongkorn Univ, Fac Med, Dept Pathol, Bangkok 10330, Thailand
[4] King Chulalongkorn Mem Hosp, Thai Red Cross Soc, Bangkok 10330, Thailand
[5] Police Gen Hosp, Dept Med, Bangkok, Thailand