Contribution of epidemiology in poland for better understanding of the natural history of diseases in gastrointestinal tract.

Descriptive epidemiologic studies on the geographical distribution of gastrointestinal diseases in Poland have been conducted in our country since several decades. One of the first descriptive analyses was cancer study in 1967, where age-standardized mortality rates in various regions of Poland by gender and area of residence (urban/rural) were presented. Since 1970 analytical epidemiologic studies aiming at explaining the natural course of various diseases within gastrointestinal tract started to produce interesting results. The first study in this field was the case-control study on the occurrence of peptic ulcer and tobacco smoking performed in 1974. The study provided one of the first epidemiologic evidence on the harmful effect of tobacco smoking in the etiology or peptic ulcers. Subsequent studies dealt with the importance of dietary habits and life style (tobacco smoking and vodka drinking) in the occurrence of gastric cancer. The studies confirmed previous findings that consumption of raw vegetables and fresh fruit is inversely related to risk for stomach cancer in Poland. In addition the results demonstrated, that dietary practices such as the modality of cooking the food, preparation of food products and storing conditions were connected with stomach cancer risk. These factors have also been found to influence the risk for stomach cancer in Poland. The main message of this latter study was that the family as a whole is affected by many risk factors for stomach cancer and families in which stomach cancer has occurred should be therefore targets for preventive measures. Interestingly, analysis of life style factors such as tobacco smoking or vodka drinking has showed that the risk for cardia cancer increased considerably for smokers of cigarettes without filters and in those who consumed large amounts of vodka. For the non-cardia region a uniform increase of risk could be observed for vodka drinking, regardless of cigarette smoking status. The findings of this study suggested the hypothesis that the effect of tobacco smoking and vodka drinking may be different for cardia cancer compared to the distal cancers. Our clinico-epidemiological study suggest that infection with Helicobacter pylori is not sufficient factor for inducing precancer changes in gastric mucosa. Besides, case-controls studies on dietary habits and physical activity level in the etiology of colorectal cancer are in progress. The preliminary results demonstrated the protective effect of higher physical activity in the occurrence of colorectal cancer after accounting for nutritional habits.