Figure 1. The procedures in establishing patient-derived xenograft models of esophageal cancer. Tumor tissues or biopsy are obtained from patients with EC during surgery or endoscopic examination. These tumor tissues and biopsy are termed P0 and are then fragmented before implantation. In some condition, cell populations are isolated from tumor tissues for PDX model establishment. Fragmented samples or primary tumor cells are then implanted into immunocompromised mice (termed P1), either subcutaneously or orthotopically. When P1 tumors reached 500~1500 mm3, fresh tumor fragments are harvested from mice and then subsequently re-implanted into other mice for expansion (P2, P3, and so on).