RESUMEN
A randomized chemoprevention trial on precancerous lesions of the stomach is being conducted in Tachira State, Venezuela. The aims of the study are to evaluate the efficacy of vitamin supplementation in preventing the progression rate of precancerous lesions. Here we report on the pilot phase of the study in which two antioxidant preparations were evaluated on their ability to raise antioxidant levels in plasma and in gastric juice. The study aimed also to determine the antibiotic sensitivity profiles of Helicobacter pylori isolates prevalent in the area. Forty-three subjects with precancerous lesions (chronic gastritis, chronic atrophic gastritis, intestinal metaplasia and dysplasia) of the stomach were randomized to one of two antioxidant treatments. Treatment 1 (250 mg of standard vitamin C, 200 mg of vitamin E and 6 mg of beta-carotene three times a day) or treatment 2 (150 mg of standard vitamin C, 500 mg of slow release vitamin C, 75 mg of vitamin E and 15 mg of beta-carotene once a day) for 7 days. Blood levels of total vitamin C, beta-carotene and alpha-tocopherol and gastric juice levels of ascorbic acid and total vitamin C were measured before and after treatment on day 8. Both treatments increased the plasma levels of total vitamin C, beta-carotene and alpha-tocopherol/cholesterol but not those of ascorbic acid or total vitamin C in gastric juice. Treatment 1 was the best choice and resulted in a greater increase in the plasma levels of beta-carotene and alpha-tocopherol. H. pylori was cultured from 90% of the gastric biopsies; 35 isolates were identified which were highly resistant to metronidazole, a front-line antibiotic recommended against H. pylori in other settings.
Asunto(s)
Antioxidantes/uso terapéutico , Infecciones por Helicobacter/prevención & control , Helicobacter pylori , Lesiones Precancerosas/prevención & control , Neoplasias Gástricas/prevención & control , Vitaminas/uso terapéutico , Adulto , Anciano , Antioxidantes/análisis , Ácido Ascórbico/administración & dosificación , Ácido Ascórbico/sangre , Ácido Ascórbico/uso terapéutico , Carotenoides/administración & dosificación , Carotenoides/sangre , Carotenoides/uso terapéutico , Quimioprevención , Enfermedad Crónica , Progresión de la Enfermedad , Femenino , Jugo Gástrico/química , Gastritis/tratamiento farmacológico , Gastritis Atrófica/tratamiento farmacológico , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/aislamiento & purificación , Humanos , Masculino , Metaplasia , Persona de Mediana Edad , Proyectos Piloto , Venezuela , Vitamina E/administración & dosificación , Vitamina E/sangre , Vitamina E/uso terapéutico , Vitaminas/análisis , Vitaminas/sangre , beta CarotenoRESUMEN
A hospital-based case-control study, including 131 cases of esophageal cancer and 381 controls, was carried out in Paraguay to investigate the role of hot and cold mate drinking in esophageal cancer risk. Detailed information on mate drinking and on tobacco smoking, alcohol consumption, and dietary habits was obtained by interview. Amount and duration of cold or hot mate drinking were not associated with esophageal cancer risk. However, temperature at which mate was drunk was significantly associated with risk. As compared to drinkers of warm or hot mate, drinkers of very hot mate had an increased risk for esophageal cancer even after adjusting for the strong effects of alcohol and tobacco consumption (adjusted odds ratio = 2.4; 95% confidence interval = 1.3-4.3). This effect seemed to be mainly due to the temperature at which mate cocido (one of the two ways in which hot mate is prepared) was drunk (odds ratio = 6.5; 95% confidence interval = 3.2-12.2). As expected, very strong dose-response associations were found for alcohol consumption and cigarette smoking. After correcting for these and the consumption of other food groups, diets rich in fats and red meats, especially beef, were associated with esophageal cancer risk. In conclusion, the findings from this study suggest that cold mate drinking does not increase the risk of esophageal cancer. This study identifies the very hot temperature at which mate is drunk, and not the amount or the duration, as an important risk factor for esophageal cancer in this population. Alcohol drinking and tobacco smoking remain, nevertheless, the main risk factors for esophageal cancer in Paraguay.
Asunto(s)
Bebidas/efectos adversos , Neoplasias Esofágicas/etiología , Conducta Alimentaria , Magnoliopsida/efectos adversos , Adulto , Distribución por Edad , Anciano , Consumo de Bebidas Alcohólicas/efectos adversos , Estudios de Casos y Controles , Frío , Intervalos de Confianza , Neoplasias Esofágicas/epidemiología , Femenino , Calor , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Paraguay/epidemiología , Análisis de Regresión , Factores de Riesgo , Distribución por Sexo , Fumar/efectos adversosRESUMEN
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.