trends during the last century: the changes were well documented especially in the USA. In the first half of the century, both the incidence and the mortality were slightly higher for women. At 50th, the levels of these statistic data were similar for both sexes. Until the end of 80th, the level of colorectal cancer incidence was about 34% higher, and the cancer mortality was even about 44 % higher for men in comparison to those for women. The trends of these cancers have increased for both sexes. The relations of smoking to both precursors (adenoma, polyps) and colorectal cancer has been investigated among others possible risk and preventable factors in different types of epidemiological studies. The influence of smoking on adenomas has been well documented: the risk was two to three times higher for smokers of 20 and more cigarettes per day compared to non-smokers. Also the dose-related effect has been repeatedly described. The higher risk of colorectal cancer has been showen among adults aged 55 and more and among smokers with long-term smoking history: 35-40 years. The level of the smoking-attributed risk is similar both for colorectal adenoma and cancer: OR 2-3 in average. Commonly, smokingcanbeassumedas ariskfactor for cancer of colonandrectum. In addition, the genetic polymorphism of metabolic enzymes glutathion-S-trans- ferase (GST), cytochrom P450 (CYP450) and N-acetyltransferase (NAT-2) is asso- ciated with the increased risk of adenoma and cancer of colon and rectum.

        Key words: smoking - adenomas - carcinom- colon - rectum- genetic polymorphism