[Helicobacter pylori infection is carcinogenic for humans]

International Agency for Research on Cancer recognized as sufficient the evidence of Helicobacter pylori (HP) infection carcinogenicity and placed it into the 1st group of carcinogens. The results of the studies performed during last years are discussed. They showed the involvement of HP in the development of stomach cancer. HP enhances mitogenesis of epithelium with translocation of immature cells on the surface of stomach mucous membrane and thus forms the targets for mutagenic and carcinogenic influences. HP takes part in the formation of mutagens, primarily of free oxygen radicals. Achlorohydria is the outcome of HP-gastritis and results in the bacterial growth in the stomach which participate in the formation of N-nitrosocompounds-well known carcinogens. Antitumor stomach defense is weakened by the decrease in the stomach of ascorbic acid, carotin and tocopherol resulting from HP-infection.