The influence of environmental factors on gastric cancer in the Northwest of Iran

Background: Despite a declining trend in the incidence of gastric cancer (GC), it is still a major global public health concern of the 21st century. It afflicts one million people and kills 750,000 annually. It is believed that both genetic and environmental factors contribute to the gastric carcinogenesis. However geographic variation and immigrant studies highlight the role of environmental factors. Objective: To evaluate the association of GC with the environmental factors of diet, helicobacter pylori (H. pylori) infection, lifestyle and occupation as well as family history in Iran.Methodology: A population based case-control study was conducted in the Northwest of Iran where one of the highest incidence rates of the world has been reported. Two hundred and seventeen cases of GC and 394 age and gender matched controls were recruited. Participants were interviewed using a structured questionnaire which elicited information on demographic characteristics, socioeconomic status, family and medical history, lifestyle (smoking, alcohol drinking and substance abuse) and occupation. Ten milliliters of each subjects blood was collected for blood grouping and to investigate presence of IgG antibodies against H. pylori using an ELISA kit which had been locally validated for this study.Results: Diet and H. pylori infection were found to be the most important determinants of GC in this study. High intake of allium vegetables and fruit, especially citrus fruit, appears to play a protective role. In addition to the consumption of fruit and vegetables, consumption of fresh fish was also inversely associated with GC. On the other, hand consumption of red meat and dairy products were positively associated with the risk of GC. Other dietary practices were also found to be important factors in the etiology of GC. People who had a preference for higher salt intake and drinking strong and hot tea were at higher risk. Finally, H. pylori infection was found to increase the risk of GC.Conclusion: This study has provided important and original information about the etiology of gastric cancer particularly in the Iranian context. These findings could be used in planning preventive strategies for this malignancy, which is a major health problem in Iran