Dr. Yokoyama is a Distinguished Director of Surgical Division at National Hospital Organization Minami Wakayama Medical Center in Wakayama, Japan. Having received his MD from Jichi Medical University, School of Medicine in 1994, Dr. Yokoyama undertook his postgraduate training first at Wakayama Medical University, School of Medicine, receiving his PhD in 2000. He became Professor in the Department of Surgical Oncology at Wakayama Medical University, School of Medicine in 2017 and then, became Director of surgical division at National Hospital Organization Minami Wakayama Medical Center. His ongoing research interests involve the molecular and cellular mechanism of invasion and metastasis of gastrointestinal cancers, tumor marker study and colorectal surgery.