en Endoscopy Endoscopy Original Research Original Research <p> <strong> Abstract </strong><strong></strong></p><p> <strong> Background: </strong>Gastric cancer is the second most common cancer and also the second </p><p>  cancer related death all over the world. In recent years recorded data for tumor </p><p>  has shown a rise in the incidence of gastric cancer in young individuals. The present </p><p>  study was designed to compare some of the epidemiologic characteristics of individuals </p><p>  suffering from gastric cancer aged below and above forty years. </p><p> <strong> Methods: </strong>This cross-sectional study was performed on 389 patients suffering </p><p>  from gastric cancer referred to a referral private clinic in Tehran during the years </p><p>  1991 and 2001. The patients were divided into two groups, those older than 40 years </p><p>  and the younger ones. The demographic information, the tumor type and location as </p><p>  well as the prevalence of the H. pylori infection was compared in the two groups. The </p><p>  collected data were entered in SPSS version 13 and analyzed using chi-square and </p><p>  fisher exact test. </p><p> <strong> Results: </strong>Fifty patients (12.9%) were reported to be lower than 40 years. The mean </p><p>  age of the patients in this group was 32.1±6.8years while the number was calculated </p><p>  to be 63.23 ± 9.7 years in the other group. The male to female ratio in the group </p><p>  younger and older than 40 years was 1.9: 1 and 2.6:1, respectively. Adenocarcinama </p><p>  and lymphoma compromised 70% and 12% of the individuals younger than 40 years </p><p>  whereas they were reported in 89.3% and 3.2% of the patients in the other group. </p><p>  While cancer in the middle third of stomach was the most frequent type in both </p><p>  groups, the prevalence of upper third gastric cancer was considerably higher in those </p><p>  younger than 40 years old (19.9% vs. 5%). H. pylori infection was seen in 23.2% of </p><p>  the younger group, while more than 56% of the older group suffered from H. pylori </p><p>  infection. There was a statistically significant difference between the two groups </p><p>  (P<0.017). </p><p> <strong> Conclusion: </strong>gastric cancer is not rare among the individuals younger than 40 </p><p>  years old. The disease is reported to be seen in the absence of H. pylori infection in </p><p>  the majority of these cases. There is a considerable difference between the prevalence </p><p>  of malignant lymphoma in this group of patients compared with the older patients. </p> gastric Cancer; H-Pylori infection; lymphoma; adenocarcinoma 170 174 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-12&slc_lang=en&sid=1 Hossein Froutan Pishbijari, Froutan@ams.ac.ir 20031947532846001670 20031947532846001670 Yes Department of Gastroenterology, Imam Khomeini Hospital, Morvarid Assefi Rad, 20031947532846001671 20031947532846001671 No Imam Khomeini Hospital, Iraj Baghi, 20031947532846001672 20031947532846001672 No Poursina Hospital, Guilan University of Medical Sciences,