1. Latest advances in clinical studies of circulating tumor cells in early and metastatic breast cancerLaura S. Munoz-Arcos, Eleonora Nicolò, Mara S. Serafini, Lorenzo Gerratana, Carolina Reduzzi, and Massimo Cristofanilli2. Can we define breast cancer HER2 status of by liquid biopsy?Serena Di Cosimo, Cinzia De Marco, Marco Silvestri, Adele Busico, Andrea Vingiani, Giancarlo Pruneri, and Vera Cappelletti3. Models to study CTCs and CTC culture methodsCristóbal Fernández-Santiago, Rafael López-López, and Roberto Piñeiro Cid4.Settling the uncertainty about unconventional circulating tumor cells: epithelial-to-mesenchymal transition, cell fusion and trogocytosisGiulia Gallerani, Tania Rossi, Manuela Ferracin, and Massimiliano Bonafè5.Circulating tumor cells in cancer-risk populations as a cancer interception toolMaría José Serrano, Christian Rolfo, José Expósito-Hernandez, Carmen Garrido-Navas, José Javier Lopez-Hidalgo, and Valeria Denninghoff6. Circulating tumor cells and host immunity: a tricky liaisonElena Muraro and Giulia Brisotto