This volume focuses on new and exciting approaches in the molecular and clinical management of gastrointestinal tumors. The first part presents recent insights into carcinogenesis, including alterations in cyclins and adhesion receptors, molecular structures which might be new targets of gene therapy. The second part of the volume offers new diagnostic tools, such as receptors for gastrointestinal hormones, proliferation markers, tumor suppressor proteins, and the multiple drug resistance gene, predicting response to therapy and prognosis in gastrointestinal tumors. The third part gives an update of successful approaches in primary and secondary prevention of colorectal carcinoma. Nutritional factors and pharmacologic agents can clearly decrease the risk, and fecal occult blood tests and endoscopy can reduce the mortality in colorectal carcinoma. Laparoscopic staging with subsequent biopsy of suspicious lymph nodes provides essential information in esophageal and gastric cancer. In locally advanced gastric cancer, preoperative chemotherapy provides sufficient evidence to investigate this approach as compared to primary surgery. Standards have recently been established in the adjuvant treatment of patients with gastrointestinal carcinoma, and promising new drugs, including monoclonal antibodies, thymidylate synthase, and topoisomerase inhibitors, as well as taxoids, are currently being tested in phase I, II, and III trials of gastrointestinal tumors.