The chemotherapy of colon cancer.

Despite extensive clinical trials, mortality from colon cancer has remained essentially unchanged since the 1950s. However, the increasing numbers of complete and partial responses seen in clinical trials suggest that colon cancer can be successfully treated by chemotherapy, but only if the antitumour selectivity can be increased by a substantial amount. This will be possible by the introduction of new drugs with more precise mechanisms of action, such as those acting specifically on signalling or cell cycle control pathways shown to be aberrant in colon cancer. Alternatively, the selectivity of present day agents may be increased considerably by the selective activation of prodrugs in tumours (ADEPT) or by targeting them to tumours using polymers. Other new approaches using vaccines or some form of gene therapy will potentiate present chemotherapy, while the introduction of positron emission tomography (PET) scanning will allow the rapid detection of agents with activity that would have been missed by conventional measurements of response.