During the last decades, the evolution of treatment - including radiotherapy, chemotherapy and targeted agents - has improved the cure and survival of patients with gastrointestinal (GI) cancer. Within the past 50 years of the EORTC's existence, significant progress has been made in the fight against cancer. During this time several cancer clinical trials were completed, and through these we are able to identify the most notable advances in GI cancer research done by the EORTC Gastrointestinal Tract Cancer Group (GI Group). Several EORTC clinical trials results have changed practice (e.g. standard of care of liver metastases of colorectal cancer has been changed by the EPOC trial) or have helped to support new treatment strategies in either early- or advanced-stage GI cancers. In addition to its clinical activities the group has started an extensive program of translational research. This changed strategy towards a translational, multidisciplinary program regarded as the basis for future developments. This review of the major achievements of the GI Group shows that it has played an important role in the scientific development of the understanding and treatment of GI cancer over the last 50 years.