The frequency of low HER2 expression in breast cancer and a comparison of prognosis between patients with HER2-low and HER2-negative breast cancer by HR status

Nanae Horisawa, Yayoi Adachi, Daiki Takatsuka, Kazuki Nozawa, Yuka Endo, Yuri Ozaki, Kayoko Sugino, Ayumi Kataoka, Haruru Kotani, Akiyo Yoshimura, Masaya Hattori, Masataka Sawaki, Hiroji Iwata