1. Fukushima Medical University Department of Minimally Invasive Surgical and Medical Oncology, , Fukushima City, Fukushima 960-1295 , Japan
2. Department of Radiology, Southern Tohoku Proton Therapy Center, Koriyama City , Fukushima 963-8052 , Japan
3. Department of Surgery, Southern Tohoku General Hospital, Koriyama City , Fukushima 963-8563 , Japan
4. Department of Gastroenterology, Southern Tohoku General Hospital, Koriyama City , Fukushima 963-8563 , Japan