P292 Cell-free DNA (cfDNA) profiling using Guardant360 in Japanese metastatic breast cancer patients oleh M. Kawashima, Y. Fujimoto, W. Tsuji, F. Yotsumoto, Y. Komi, H. Suwa, T. Taji, A. Izumi, M. Torii, Y. Matsutani, E. Suzuki, M. Tokiwa, N. Kawaguchi-Sakita, Y. Mori, A. Yamaguchi, K. Kawaguchi, M. Takada, M. Toi