bismuth-tripotassium-dicitrate and Precancerous-Conditions

A double-blind, placebo-controlled trial is being conducted in a population at high risk for gastric cancer in Venezuela. The main aim of the trial is to assess the effect of antioxidant vitamins (beta-carotene, vitamin C and vitamin E) in blocking the progression of precancerous lesions of the stomach. Within the framework of a screening programme for stomach cancer, 2200 subjects of 35-69 years of age have been recruited. At study entry, a dietary questionnaire was completed, and gastroscopy with the collection of seven gastric biopsies was performed. After baseline examinations, the study participants were randomized to receive antioxidant treatment or placebo for three years. The treatment phase will be completed in mid-1998. At the end of the treatment phase, the investigations performed at study entry will be repeated. Before the initiation of the trial, various pilot studies were carried out that showed an extremely high prevalence of Helicobacter pylori infection (over 90%). Two eradication trials using anti-H. pylori treatments that give good results in Europe and North America gave very poor results in our study population. The low eradication rates achieved (5-20%) suggest a high prevalence of antibiotic-resistant H. pylori strains or high reinfection rates. These disappointing results led to deletion of an anti-H. pylori treatment phase of the main trial.

Topics: Adult; Aged; Amoxicillin; Anti-Bacterial Agents; Anticarcinogenic Agents; Antioxidants; Clarithromycin; Double-Blind Method; Female; Helicobacter Infections; Helicobacter pylori; Humans; Male; Metronidazole; Middle Aged; Omeprazole; Organometallic Compounds; Placebos; Precancerous Conditions; Stomach Neoplasms; Vitamins

The bacterium Helicobacter pylori (HP) has been implicated in the etiology of precancerous lesions of the stomach and there is evidence suggesting that it may influence the efficacy of chemoprevention of gastric cancer with vitamin C. Eradication seldom has been attempted in populations from developing countries, with a high prevalence of HP frequently resistant to metronidazole. A randomized, double-blind, controlled trial to evaluate the efficacy of colloidal bismuth subcitrate (120 mg q.i.d.) and amoxycillin (500 mg q.i.d.) in eradicating HP was conducted in 220 subjects drawn from a population with a high prevalence of metronidazole-resistant HP in Tachira state, Venezuela. One month after completion of two weeks' treatment, eradication rates of 6.5 percent in the treatment group and two percent in the placebo group were estimated on the basis of HP diagnosis in biopsies, and of 13.9 percent compared with 3.9 percent on the basis of a 14C-urea breath test, although the negative predictive value of the breath test was very low compared with HP diagnosis in biopsies. In the treatment group, particularly among males, a significant decrease in bacterial load was detected. Reasons for failure of treatment in high HP-prevalence areas are discussed, and it is suggested that primary prevention of HP infection may be the optimal approach to reducing levels of stomach cancer in these high-risk groups.

Topics: Adult; Aged; Amoxicillin; Anti-Bacterial Agents; Bismuth; Double-Blind Method; Female; Helicobacter pylori; Humans; Male; Middle Aged; Organometallic Compounds; Placebos; Precancerous Conditions; Risk Factors; Stomach; Stomach Neoplasms; Venezuela