This book is a comprehensive understanding of the evolution of pre-malignant disease, emphasizing common themes in the field, including stem cell biology and histologic modes of cancer progression between the distal esophagus and stomach. Its sixteen chapters discuss metaplastic tissue change in the upper GI, clonalexpansion of early neoplasia, stem cell dynamics in experimental models, pathology of early esophageal squamous cell carcinoma, therapeutic modalities for esophageal squamous cell carcinoma, pathology of Barrett’s esophagus, screening, early detection and novel diagnostic tools for Barrett's esophagus, clonal evolution of Barrett’s esophagus, endoscopic therapeutic modalities of early esophageal cancer, pathology of early gastric cancer, and experimental models for gastric cancer.