Chemoprevention in gastrointestinal adenocarcinoma: for few but not for all?

Despite the general progress of the last two decades in oncogenesis mechanism comprehension, in screening and surveillance programs, in technological support to diagnosis and in treatment protocols, the long-term survival of gastrointestinal (GI) cancer patients is not substantially changed. Therefore chemoprevention strategies still appear as a possible alternative to screening and surveillance programs in reducing the incidence and the mortality for GI cancer, at an acceptable cost/effectiveness ratio. The present review is focused on three GI cancers: esophageal adenocarcinoma, gastric cancer and colorectal cancer and their respective precarcinogenic lesions. The authors examine, for each neoplasia, the available chemopreventive agents, their mechanism of action in preventing cancer, the potential targets in the cell growth process, the cost/effectiveness ratio and, whenever present in literature, a comparison with other cancer prevention strategies. The authors conclude that, at present, with the available agents, chemoprevention is not indicated for all patients at low or moderate risk for GI cancer, and should not be considered as a substitute for endoscopic surveillance. In high-risk patients only, both chemoprevention and surveillance could be used. In future more specific agents and combined therapies should be tested in specific group of patients identified by their genomic susceptibility to develop cancer and responsiveness to therapy.