(2005), which makes this type of work of primordial importance. Att empts at early diagnoses will always be crucial and important crucial in order to change the today’s reality in which 80% of these lesions are diagnosed in later stages.In this issue of the magazine, Dr. Emura et al (7) presented the results of two mas-sive campaigns in Bogota which used endoscopy to screen for premalignant lesions and gastric cancer. 650 patients were evaluated using a standardized protocol for systema-tic endoscopy with the use of chromoscopy, electronic-optical narrow band imaging (Olympus) and indigo carmine supravital stain. Premalignant gastric lesions (atrophic gastritis, intestinal metaplasia and dysplasia) were found in 30% of the patients in the study. Two cases of early gastric cancer were found as well.Th e country with most experience in screening for gastric cancer is Japan, with the emergence in 2008 of guidelines for screening based on systematic review and evalua-tion of methods used over the past 40 years (1). Th e objective was to evaluate methods in light of available evidence and experience in recent years.Around 1960, photofl uorography to screen for gastric cancer started to be used in the prefecture of Miyagi. Th is practice was adopted as a public health strategy throughout the country. In 1983 a Health Service law was introduced for gastric cancer screening for all residents aged 40 and older. In 2004, 4.4 million people participated for a scree-ning rate of 13% (2). Fluoroscopy is recommended based on results of case-control and cohort studies. Other methods used include endoscopy, serum pepsinogen and testing for antibodies to H. pylori. All used in the clinical sett ing as opportune methods of screening. Th ese concepts were outlined by Tashiro in 2006 (5). At this point, I think it is important to remember that two types of screening exist: population screening referred to in the article by Dr. Emura (7) is applied to a geogra-phically defi ned population. It has a program covering most of the population of that area, which, if not complete, covers a representative sample of the study population as determined by an appropriate sampling. Th us, results of this type of study retain their external validity and can be used later in health policy making. Th e other type is oppor-tune screening performed within the clinical sett ing. Th e primary objective of this type of study is measured in decreases of the incide nce and mortality and thus implies moni-toring. Continuing with the analysis of population screening studies, our key outcome is mortality. Patients in this type of study should be followed up on for at least 5 years.