As opposed to the previous study,8 our study focused on long term risks; we applied a two year lag time, during which a large peak in incidence was observed. This peak is mainly the result of selection bias—that is, the outcome has an effect on the probability of being examined and thus recruited. Therefore, most of the gastric cancers diagnosed in the first two years were likely present—and overlooked—at the initial investigation or were in such an imminent precancerous stage that they were already symptomatic. Although dysplasia, and particularly severe dysplasia,8 is a powerful signal that a gastric cancer may be present (and should heighten clinical observation and prompt repeated endoscopy8 11) the concentration of cases in the first two years may blur assessments of the long term prognosis. After two years the peak was passed, so our present data do not include the initially overlooked prevalent cases. This is probably the principal reason for the discrepancy between studies for excess incidence of gastric cancer after a diagnosis of dysplasia (less advanced lesions were much less indicative of a prevalent cancer). None the less, throughout the 15-20 years of follow-up, during which we had sufficient power to monitor the long term progression, patients with dysplasia remained at substantially increased risk. Whether this increase merits institution of scheduled surveillance programmes and, if so, how often and in which ages, must be subject to careful cost-benefit deliberations. Such analysis should ideally provide estimated costs; number of cases of gastric cancer diagnosed and deaths prevented; life years, or quality adjusted life years gained, or both; and incremental cost effectiveness ratio, in association with different screening strategies defined by a combination of, for example, starting age, screening frequency, and risk stratums.