On the basis of four cases of cancer of the stomach occurring after surgery for benign gastroduodenal lesions, the authors analyse 1690 cases published in the literature. The development of these cancers, which occur much more frequently than in the normal population, is favoured by all of the local pathophysiological consequences of the initial operation, although no one factor is predominant. These cancers have a very poor prognosis, with a mean 5 year survival of 6.9%. These very disappointing results can only be improved by early detection as a result of systematic endoscopic follow-up.