Digestive System Tumours is the first volume in the fifth edition of the WHO series on the classification of human tumors. This series (also known as the WHO Blue Books) is regarded as the gold standard for the diagnosis of tumors and comprises a unique synthesis of histopathological diagnosis with digital and molecular pathology. These authoritative and concise reference books provide indispensable international standards for anyone involved in the care of patients with cancer or in cancer research, underpinning individual patient treatment as well as research into all aspects of cancer causation, prevention, therapy, and education.