No axillary surgical treatment for lymph node-negative patients after ultra-sonography [NAUTILUS]: protocol of a prospective randomized clinical trial. - Jung, Ji Gwang; Ahn, Se Hyun; Lee, Seeyoun; Kim, Eun-Kyu; Ryu, Jai Min; Park, Seho; Lim, Woosung; Jung, Yong Sik; Chung, Il Yong; Jeong, Joon; Chang, Ji Hyun; Shin, Kyung Hwan; et al. (BMC Cancer, 2022)