Helicobacter pylori Antimicrobial Resistance and Gene Variants in High- and Low-Gastric-Cancer-Risk Populations.

Colombia, South America has one of the world's highest burdens of Helicobacter pylori infection and gastric cancer. While multidrug antibiotic regimens can effectively eradicate H. pylori, treatment efficacy is being jeopardized by the emergence of antibiotic-resistant H. pylori strains. Moreover, the spectrum of and genetic mechanisms for antibiotic resistance in Colombia is underreported. In this study, 28 H. pylori strains isolated from gastric biopsy specimens from a high-gastric-cancer-risk (HGCR) population living in the Andes Mountains in Túquerres, Colombia and 31 strains from a low-gastric-cancer-risk (LGCR) population residing on the Pacific coast in Tumaco, Colombia were subjected to antibiotic susceptibility testing for amoxicillin, clarithromycin, levofloxacin, metronidazole, rifampin, and tetracycline. Resistance-associated genes were amplified by PCR for all isolates, and 29 isolates were whole-genome sequenced (WGS). No strains were resistant to amoxicillin, clarithromycin, or rifampin. One strain was resistant to tetracycline and had an A926G mutation in its 16S rRNA gene. Levofloxacin resistance was observed in 12/59 isolates and was significantly associated with N87I/K and/or D91G/Y mutations in gyrA Most isolates were resistant to metronidazole; this resistance was significantly higher in the LGCR (31/31) group compared to the HGCR (24/28) group. Truncations in rdxA and frxA were present in nearly all metronidazole-resistant strains. There was no association between phylogenetic relationship and resistance profiles based on WGS analysis. Our results indicate H. pylori isolates from Colombians exhibit multidrug antibiotic resistance. Continued surveillance of H. pylori antibiotic resistance in Colombia is warranted in order to establish appropriate eradication treatment regimens for this population.

The Colombian Chemoprevention Trial: 20-Year Follow-Up of a Cohort of Patients With Gastric Precancerous Lesions.

BACKGROUND & AIMS: Helicobacter pylori eradication and endoscopic surveillance of gastric precancerous lesions are strategies to reduce gastric cancer (GC) risk. To our knowledge, this study is the longest prospective cohort of an H pylori eradication trial in a Hispanic population. METHODS: A total of 800 adults with precancerous lesions were randomized to anti-H pylori treatment or placebo. Gastric biopsy samples taken at baseline and 3, 6, 12, 16, and 20 years were assessed by our Correa histopathology score. A generalized linear mixed model with a participant-level random intercept was used to estimate the effect of H pylori status on the score over time. Logistic regression models were used to estimate progression by baseline diagnosis and to estimate GC risk by intestinal metaplasia (IM) subtype and anatomic location. RESULTS: Overall, 356 individuals completed 20 years of follow-up. Anti-H pylori therapy (intention-to-treat) reduced progression of the Correa score (odds ratio [OR], 0.59; 95% confidence interval [CI], 0.38-0.93). H pylori-negative status had a beneficial effect on the score over time (P = .036). Among individuals with IM (including indefinite for dysplasia) at baseline, incidence rates per 100 person-years were 1.09 (95% CI, 0.85-1.33) for low-grade/high-grade dysplasia and 0.14 (95% CI, 0.06-0.22) for GC. Incomplete-type (vs complete-type) IM at baseline presented higher GC risk (OR, 13.4; 95% CI, 1.8-103.8). Individuals with corpus (vs antrum-restricted) IM showed an OR of 2.1 (95% CI, 0.7-6.6) for GC. CONCLUSIONS: In a high-GC-risk Hispanic population, anti-H pylori therapy had a long-term beneficial effect against histologic progression. Incomplete IM is a strong predictor of GC risk.

Contrasting serum biomarker profiles in two Colombian populations with different risks for progression of premalignant gastric lesions during chronic Helicobacter pylori infection.

BACKGROUND: Colombians in coastal Tumaco have a lower incidence of Helicobacter pylori-associated gastric cancer compared to individuals from Tuquerres in the high Andes. This is despite nearly universal prevalence of H. pylori infection and chronic gastritis. METHODS: H. pylori infection was confirmed by Steiner stain and serology using African and European-origin strains. Gastric histology and serum inflammatory biomarkers in dyspeptic Tumaco or Tuquerres patients were evaluated to predict progression of gastric lesions. RESULTS: H. pylori infection was nearly universal by Steiner stain and serology. IgG response to European-origin H. pylori strains were greater than African-origin. High gastric cancer-risk Tuquerres patients, compared to low-risk Tumaco, had significant odds ratios for lesion progression associated with serum IL-5, trefoil factor 3 (TFF3), and low pepsinogen I/II ratio. Sensitivity and specificity for these parameters was 63.8% and 67.9%, respectively, with correctly classifying patients at 66.7%. Most odds ratios for 26 other biomarkers were significant for the town of residency, indicating an environmental impact on Tumaco patients associated with decreased lesion progression. CONCLUSION: An IL-5 association with progression of gastric lesions is novel and could be evaluated in addition to TFF3 and pepsinogen I/II ratio as a non-invasive prognostic screen. Results suggest Tumaco patients were exposed to infectious diseases beyond H. pylori such as the documented high incidence of helminthiasis and toxoplasmosis. IMPACT: Results support a prior recommendation to evaluate TFF3 and pepsinogen I/II together to predict aggressive gastric histology. Our data indicate IL-5 should be further evaluated as prognostic parameter.

Draft Genome Sequences of 13 Colombian Helicobacter pylori Strains Isolated from Pacific Coast and Andean Residents.

We present here the draft genomes of 13 Helicobacter pylori strains isolated from Colombian residents on the Pacific coast (n = 6) and in the Andes mountains (n = 7), locations that differ in gastric cancer risk. These 13 strains were obtained from individuals with diagnosed gastric lesions.

Different gastric microbiota compositions in two human populations with high and low gastric cancer risk in Colombia.

Inhabitants of Túquerres in the Colombian Andes have a 25-fold higher risk of gastric cancer than inhabitants of the coastal town Tumaco, despite similar H. pylori prevalences. The gastric microbiota was recently shown in animal models to accelerate the development of H. pylori-induced precancerous lesions. 20 individuals from each town, matched for age and sex, were selected, and gastric microbiota analyses were performed by deep sequencing of amplified 16S rDNA. In parallel, analyses of H. pylori status, carriage of the cag pathogenicity island and assignment of H. pylori to phylogeographic groups were performed to test for correlations between H. pylori strain properties and microbiota composition. The gastric microbiota composition was highly variable between individuals, but showed a significant correlation with the town of origin. Multiple OTUs were detected exclusively in either Tumaco or Túquerres. Two operational taxonomic units (OTUs), Leptotrichia wadei and a Veillonella sp., were significantly more abundant in Túquerres, and 16 OTUs, including a Staphylococcus sp. were significantly more abundant in Tumaco. There was no significant correlation of H. pylori phylogeographic population or carriage of the cagPAI with microbiota composition. From these data, testable hypotheses can be generated and examined in suitable animal models and prospective clinical trials.

Processed meat consumption and squamous cell carcinoma of the oesophagus in a large case-control study in Uruguay.

BACKGROUND: The role of processed meat in the aetiology of squamous cell oesophageal cancer has been explored in detail. METHODS: In the time period 1990-2005, a case-control study was conducted in Montevideo, Uruguay including 2,368 participants (876 cases of oesophageal cancer and 1,492 controls). Relative risks, approximated by the odds ratios, were estimated by multiple unconditional logistic regression. RESULTS: Processed meat was positively associated with oesophageal cancer (upper quartile vs lower quartile OR 2.30, 95%CI 1.72-3.07), whereas salted meat intake was positively associated with squamous cell oesophageal cancer (OR 3.82, 95%CI 2.74-5.33). Finally other cured meats were positively associated with oesophageal cancer (OR 1.65, 95%CI 1.22- 2.22). CONCLUSIONS: It could be concluded that processed meat consumption could be an important risk factor for the aetiology of squamous cell oesophageal cancer in Uruguay.

Diet patterns and risk of squamous cell oesophageal carcinoma: a case-control study in Uruguay.

BACKGROUND: Oesophageal cancer presents high incidence rates in the so-called Brazilian-Uruguayan belt. MATERIALS AND METHODS: The present study included 1,170 participants (234 cases and 936 controls) which were analyzed by unconditional multiple logistic regression in order to examine risk of oesophageal squamous cell carcinoma (OESCC) associated with several food groups. RESULTS: Boiled red meat (OR 2.59, 95%CI 1.69-3.97), lamb meat (OR 1.64, 95%CI 1.07-2.51), processed meat (OR 1.49, 95%CI 1.01-2.21), whole milk (OR 1.78, 1.19-1.68), fresh vegetables and fruits (OR 0.42, 95%CI 0.27-0.63), mate consumption (OR 2.04, 95%CI 1.32- 3.16), and black tea (OR 0.10, 95%CI 0.04-0.28) were significantly associated with risk of OESCC. CONCLUSIONS: Hot beverages (mate) and hot foods (boiled meat) appear to be important determinants in the risk of OESCC, allowing the penetration of carcinogens in tobacco and alcohol into the oesophageal mucosa.

Activation of EGFR and ERBB2 by Helicobacter pylori results in survival of gastric epithelial cells with DNA damage.

BACKGROUND & AIMS: The gastric cancer-causing pathogen Helicobacter pylori up-regulates spermine oxidase (SMOX) in gastric epithelial cells, causing oxidative stress-induced apoptosis and DNA damage. A subpopulation of SMOX(high) cells are resistant to apoptosis, despite their high levels of DNA damage. Because epidermal growth factor receptor (EGFR) activation can regulate apoptosis, we determined its role in SMOX-mediated effects. METHODS: SMOX, apoptosis, and DNA damage were measured in gastric epithelial cells from H. pylori-infected Egfr(wa5) mice (which have attenuated EGFR activity), Egfr wild-type mice, or in infected cells incubated with EGFR inhibitors or deficient in EGFR. A phosphoproteomic analysis was performed. Two independent tissue microarrays containing each stage of disease, from gastritis to carcinoma, and gastric biopsy specimens from Colombian and Honduran cohorts were analyzed by immunohistochemistry. RESULTS: SMOX expression and DNA damage were decreased, and apoptosis increased in H. pylori-infected Egfr(wa5) mice. H. pylori-infected cells with deletion or inhibition of EGFR had reduced levels of SMOX, DNA damage, and DNA damage(high) apoptosis(low) cells. Phosphoproteomic analysis showed increased EGFR and erythroblastic leukemia-associated viral oncogene B (ERBB)2 signaling. Immunoblot analysis showed the presence of a phosphorylated (p)EGFR-ERBB2 heterodimer and pERBB2; knockdown of ErbB2 facilitated apoptosis of DNA damage(high) apoptosis(low) cells. SMOX was increased in all stages of gastric disease, peaking in tissues with intestinal metaplasia, whereas pEGFR, pEGFR-ERBB2, and pERBB2 were increased predominantly in tissues showing gastritis or atrophic gastritis. Principal component analysis separated gastritis tissues from patients with cancer vs those without cancer. pEGFR, pEGFR-ERBB2, pERBB2, and SMOX were increased in gastric samples from patients whose disease progressed to intestinal metaplasia or dysplasia, compared with patients whose disease did not progress. CONCLUSIONS: In an analysis of gastric tissues from mice and patients, we identified a molecular signature (based on levels of pEGFR, pERBB2, and SMOX) for the initiation of gastric carcinogenesis.

Present and past Helicobacter pylori infection in Mexican school children.

BACKGROUND: In developing countries, more than 50% of children have serological evidence of Helicobacter pylori infection. However, serological tests for H. pylori did not differentiate between active and past infection. The objectives of this study were to estimate the frequency of active and past H. pylori infection utilizing functional urea breath test (UBT) and serological tests and evaluate factors associated with the infection. METHODS: A total of 675 school children, 6-13 years of age, participated. UBT was performed to detect active H. pylori infection. Blood samples were obtained to determine iron status and Immunoglobulin G (IgG) responses to the H. pylori whole-cell and to Cag A antigens by antigen-specific enzyme-linked immunosorbent assays. Weight, height, and sociodemographic characteristics were recorded. RESULTS: A total of 37.9% (95% Confidence Intervals (CI): 34.2-41.6) of school children had active or past H. pylori infection; of them, 73.8% (CI95% 68.4-79.2) were carrying CagA-positive strain, 26.5% (CI95% 23.2-29.8) had active infection, and 11.4% (95%CI: 9.0-13.8) had evidence of past H. pylori infection. School children with iron deficiency and low height for age had higher risk of H. pylori infection: [OR to active or past infection was 2.30 (CI 95% 1.01-5.23) and to active infection it was 2.64 (CI 95% 1.09-6.44)] compared to school children with normal iron status and height for age or with normal iron status but low height for age or with iron deficiency and normal height for age. CONCLUSIONS: The estimated prevalence of infection depends of the test utilized. Frequency of H. pylori infection and carrying CagA-positive strains was high in this population. Malnutrition was associated with active H. pylori infection.

Draft Genome Sequences of Helicobacter pylori Strains Isolated from Regions of Low and High Gastric Cancer Risk in Colombia.

The draft genome sequences of six Colombian Helicobacter pylori strains are presented. These strains were isolated from patients from regions of high and low gastric cancer risk in Colombia and were characterized by multilocus sequence typing. The data provide insights into differences between H. pylori strains of different phylogeographic origins.

Gastric cancer: Overview / Cáncer Gastrico: Punto de vista

Abstract Gastric cancer ranks fourth in incidence and second in mortality among all cancers worldwide. Despite the decrease in incidence in some regions of the world, gastric cancer continues to present a major clinical challenge due to most cases being diagnosed in advanced stages with poor prognosis and limited treatment options. The development of gastric cancer is a complex and multifactorial process involving a number of etiological factors and multiple genetic and epigenetic alterations. Among the predisposing factors are: Helicobacter pylori infection, high salt intake, smoking, and in a small percentage of patients, a familial genetic component. More than 95% of stomach cancer cases are adenocarcinomas, which are classified into two major histologic types: intestinal and diffuse. Intestinal type adenocarcinoma is preceded by a sequence of gastric lesions known as Correa´s cascade and is the histologic type associated with the global decrease in gastric cancer rates. Diffuse type adenocarcinomas have a more aggressive behavior and worse prognosis than those of the intestinal type. According to the anatomical location, adenocarcinomas are classified as proximal (originating in the cardia) and distal (originating in the body and antrum). This classification seems to recognize two different clinical entities. Surgical resection of the tumor at an early stage is the only effective treatment method. Therefore, the identification and surveillance of patients at risk may play a significant role in survival rates. Anti-Helicobacter pylori therapy has been shown to be an effective measure in the prevention of gastric cancer.

Resumen El cáncer gástrico ocupa el cuarto lugar en incidencia y el segundo en mortalidad entre todos los cánceres en todo el mundo. A pesar de la disminución de la incidencia en algunas regiones del mundo, el cáncer gástrico continúa siendo un reto clínico debido a que la mayoría de los casos se diagnostican en etapas avanzadas con mal pronóstico y las opciones de tratamiento limitadas. El desarrollo de cáncer gástrico es un proceso complejo y multifactorial que implica un número de factores etiológicos y múltiples alteraciones genéticas y epigenéticas. Entre los factores predisponentes están: infección por Helicobacter pylori, alto consumo de sal, tabaquismo, y en un pequeño porcentaje de los pacientes, un componente genético familiar. Más del 95% de los casos de cáncer de estómago son adenocarcinomas, que se clasifican en dos principales tipos histológicos: intestinal y difuso. Adenocarcinoma de tipo intestinal es precedida por una secuencia de lesiones gástricas conocidas como cascada de Correa y es el tipo histológico asociado con la disminución global de las tasas de cáncer gástrico. Los Adenocarcinomas de tipo difuso tienen un comportamiento más agresivo y peor pronóstico que aquellos del tipo intestinal. De acuerdo con la localización anatómica, los adenocarcinomas se clasifican como proximal (originario en el cardias) y distal (que se origina en el cuerpo y antro). Esta clasificación parece reconocer dos entidades clínicas diferentes. La resección quirúrgica del tumor en una etapa temprana es el método de tratamiento eficaz. Por lo tanto, la identificación y vigilancia de los pacientes de alto riesgo pueden desempeñar un papel importante en las tasas de supervivencia. La terapia anti-Helicobacter pylori ha demostrado ser una medida eficaz en la prevención del cáncer gástrico.

Use of the noninvasive entero-test in the detection of Helicobacter pylori in children in an endemic area in Colombia.

BACKGROUND AND OBJECTIVE: Gastric infection with Helicobacter pylori (H pylori), a strong risk factor for gastric cancer, is highly prevalent in children residing in the Colombian Andes. We aimed to validate the use of the Entero-test to culture and genotype H pylori strains from asymptomatic Colombian children. METHODS: Children (ages 10-15 years, n = 110, 80 of which were H pylori positive by the urea breath test [UBT]) were subjected to the Entero-test, and strings were cultured and/or used for DNA extraction for polymerase chain reaction (PCR). These children had been treated for H pylori in 2007. A second population of children (ages 10-15 years, n = 95),which had not been previously treated, was also subjected to the Entero-test. RESULTS: Of UBT-positive children in the treated group, 29 of 80 (36%) Entero-test samples were H pylori culture positive; 29 additional string extracts were tested by PCR for the H pylori virulence factors cagA and vacA. PCR from cultures and extracts yielded a sensitivity of 74% and specificity of 87%. In the untreated group, 16 of 94 UBT-positive children (17%) produced Entero-tests that were culture positive. Fifty-eight of 94 (62%) string extracts were PCR positive for cagA and/or vacA. In previously treated children, H pylori strains were more often the less virulent vacA s2 (P = 0.001), m2 (P = 0.006), and i2 genotypes (P = 0.039). CONCLUSIONS: The Entero-test may be used as a noninvasive test to detect H pylori in asymptomatic children residing in high-risk areas for gastric cancer. Treatment of H pylori in children was associated with less virulent genotypes.

Genome sequences of 65 Helicobacter pylori strains isolated from asymptomatic individuals and patients with gastric cancer, peptic ulcer disease, or gastritis.

Helicobacter pylori, inhabitant of the gastric mucosa of over half of the world population, with decreasing prevalence in the U.S., has been associated with a variety of gastric pathologies. However, the majority of H. pylori-infected individuals remain asymptomatic, and negative correlations between H. pylori and allergic diseases have been reported. Comprehensive genome characterization of H. pylori populations from different human host backgrounds including healthy individuals provides the exciting potential to generate new insights into the open question whether human health outcome is associated with specific H. pylori genotypes or dependent on other environmental factors. We report the genome sequences of 65 H. pylori isolates from individuals with gastric cancer, preneoplastic lesions, peptic ulcer disease, gastritis, and from asymptomatic adults. Isolates were collected from multiple locations in North America (USA and Canada) as well as from Columbia and Japan. The availability of these H. pylori genome sequences from individuals with distinct clinical presentations provides the research community with a resource for detailed investigations into genetic elements that correlate either positively or negatively with the epidemiology, human host adaptation, and gastric pathogenesis and will aid in the characterization of strains that may favor the development of specific pathology, including gastric cancer.

Meat, milk and risk of lymphoid malignancies: a case-control study in Uruguay.

In the time period 1996-2004, 697 cases with lymphoid neoplasms and 3606 controls with nonneoplastic conditions were included in a case-control study conducted in the Cancer Institute of Uruguay. They were administered a routine questionnaire that included 8 sections and a food frequency questionnaire focused on intakes of total meat, red meat, salted meat, barbecued meat, processed meat, milk, total vegetables and total fruits, and alcoholic beverages. Lymphoid cancers were analyzed by multiple polytomous regression. Red meat, salted meat, and milk were positively associated with risk of lymphoid cancers [odds ratios (OR) for the highest tertile vs. the lowest one of red meat = 1.68, 95% confidence interval (CI) 1.37-2.08, OR for whole milk = 2.92, 95% CI 2.63-3.63). On the other hand, plant foods, particularly total fruits, and alcoholic beverages (mainly red wine) were protective. We could conclude that these foods could play a significant role in the etiology of lymphoid malignancies.

Dietary patterns and risk of cancers of the upper aerodigestive tract: a factor analysis in Uruguay.

In the time period 1996-2004, we conducted a case-control study in Montevideo, Uruguay with the objective of exploring the role of foods and alcoholic beverages in the etiology of cancers of the upper aerodigestive tract (UADT). In brief, 563 male cases and 1099 male controls were frequency matched on age and residence using random sampling. All the participants were drawn from the 4 major public hospitals in Montevideo. We used exploratory factor analysis among controls. Through Scree plot test, the model retained 4 factors, which were labeled as prudent, starchy plants, Western, and drinker. These dietary patterns explained 34.8% of the total variance. Whereas the prudent pattern was inversely associated with UADT cancer [odds ratios (OR) for the upper tertile vs. the lowest one 0.52, 95% confidence intervals 0.32-0.76, P value for trend = 0.0005), the remaining patterns were significantly and positively associated with UADT cancers. We conclude that these patterns were similar among the oral and laryngeal cancers, both in the direction of the ORs and in the magnitude of the associations, suggesting that these cancer sites share the effect of dietary patterns in the etiology of cancer of the upper aerodigestive tract.

Nutrient-based dietary patterns of head and neck squamous cell cancer: a factor analysis in Uruguay.

OBJECTIVE: The aim of this study was to investigate the association between nutrient-based dietary patterns and squamous cell cancers of the head and neck. METHODS: We used a case-control study which included 548 cases and 548 controls. From these participants, we derived 23 nutrients and they were then submitted to a factorability analysis in order to conduct a principal component factor analysis. RESULTS: We were able to identify four nutrient-derived patterns. The first pattern (meat-based pattern) was positively associated with squamous cell cancer of the head and neck (OR 2.85, 95 % CI 1.81-4.15), whereas the third pattern (fruit-based) was strongly protective (OR 0.43, 95 % CI 0.27-0.63). The other nutrient patterns were also significantly associated with head and neck squamous cell carcinoma with minor ORs. CONCLUSION: Both patterns suggest that red meat and fruits are major factors in the etiology of head and neck squamous cell cancer, replicating previous studies in the field.

Gastric cáncer: Overview.

Gastric cancer ranks fourth in incidence and second in mortality among all cancers worldwide. Despite the decrease in incidence in some regions of the world, gastric cancer continues to present a major clinical challenge due to most cases being diagnosed in advanced stages with poor prognosis and limited treatment options. The development of gastric cancer is a complex and multifactorial process involving a number of etiological factors and multiple genetic and epigenetic alterations. Among the predisposing factors are: Helicobacter pylori infection, high salt intake, smoking, and in a small percentage of patients, a familial genetic component. More than 95% of stomach cancer cases are adenocarcinomas, which are classified into two major histologic types: intestinal and diffuse. Intestinal type adenocarcinoma is preceded by a sequence of gastric lesions known as Correa´s cascade and is the histologic type associated with the global decrease in gastric cancer rates. Diffuse type adenocarcinomas have a more aggressive behavior and worse prognosis than those of the intestinal type. According to the anatomical location, adenocarcinomas are classified as proximal (originating in the cardia) and distal (originating in the body and antrum). This classification seems to recognize two different clinical entities. Surgical resection of the tumor at an early stage is the only effective treatment method. Therefore, the identification and surveillance of patients at risk may play a significant role in survival rates. Anti-Helicobacter pylori therapy has been shown to be an effective measure in the prevention of gastric cancer.

El cáncer gástrico ocupa el cuarto lugar en incidencia y el segundo en mortalidad entre todos los cánceres en todo el mundo. A pesar de la disminución de la incidencia en algunas regiones del mundo, el cáncer gástrico continúa siendo un reto clínico debido a que la mayoría de los casos se diagnostican en etapas avanzadas con mal pronóstico y opciones de tratamiento limitadas. El desarrollo de cáncer gástrico es un proceso complejo y multifactorial que implica un número de factores etiológicos y múltiples alteraciones. Entre genética y epigenética los factores predisponentes son: infección por Helicobacter pylori, alto consumo de sal, fumar, y en un pequeño porcentaje de los pacientes, un componente genético familiar. Más del 95% de los casos de cáncer de estómago son adenocarcinomas, que se clasifican en dos principales tipos histológicos: intestinal y difuso. Adenocarcinomas de tipo intestinal están precedidos por una secuencia de lesiones gástricas conocidas como cascada de Correa y es el tipo histológico asociado con la disminución global de las tasas de cáncer gástrico. Adenocarcinomas de tipo difuso tienen un comportamiento más agresivo y peor pronóstico que aquellos del tipo intestinal. De acuerdo con la localización anatómica, los adenocarcinomas se clasifican como proximal (originario en el cardias) y distal (que se origina en el cuerpo y antro). Este clasificación parece reconocer dos entidades clínicas diferentes. La resección quirúrgica del tumor en estadios tempranos es el único método de tratamiento efectivo. Por lo tanto, la identificación y vigilancia de los pacientes en situación de riesgo pueden desempeñar un papel importante en las tasas de supervivencia. El tratamiento Anti-Helicobacter pylori ha demostrado ser una medida eficaz en la prevención del cáncer gástrico.

Maté consumption and risk of oral cancer: Case-control study in Uruguay.

BACKGROUND: In the period 1990 to 2001, a case-control study on oral cancer and maté consumption was conducted at the Cancer Institute of Uruguay. METHODS: The study included 696 newly diagnosed cases with squamous cell carcinoma and 696 controls afflicted with nonneoplastic conditions not related to tobacco smoking and alcohol drinking. The participants were matched on age and residence and the study was restricted to men. RESULTS: In order to control confounding for tobacco and alcohol, we fitted 2 models. According to model 1, the odds ratio (OR) for maté consumption was 1.15 (95% confidence interval [CI], 0.76-1.73), whereas the results for model 2 showed an OR of 3.47 (95% CI, 1.60-7.52). CONCLUSIONS: The inclusion of a term for the interaction between maté and smoking (or drinking) was rewarding and the ORs were even higher than those observed with the crude estimates.