Tumor Location Is Associated With the Prevalence of Braf And Pik3ca Mutations in Patients with Wild-Type Ras Colorectal Cancer: A Prospective Multi-Center Cohort Study in Japan oleh Hiroya Taniguchi, Keisuke Uehara, Goro Nakayama, Hiroshi Nakayama, Toshisada Aiba, Norifumi Hattori, Masato Kataoka, Yasuyuki Nakano, Yoshihisa Kawase, Osamu Okochi, Hiroshi Matsuoka, Setsuo Utsunomiya, Eiji Sakamoto, Yoshinori Mori, Shinichi Umeda, Toshio Shikano, Koji Komori, Masahiro Tajika, Shigenori Kadowaki, Kei Muro, Yasushi Yatabe