Tobacco smoking increases the risk for gastric adenocarcinoma among Helicobacter pylori-infected individuals

Cancer incidence in the Somali population of Olmsted County: A Rochester epidemiology project study

BACKGROUND

Somali immigrants and refugees constitute one of the largest African ethnic groups immigrating to the United States over the past three decades with the majority resettling in the state of Minnesota. Previous studies have documented significant cancer screening disparities between the Somali population and the general population. However, little is known about cancer incidence among Somali groups living in the United States.

METHODS

We determined the incidence of 18 types or sites of malignancy using ICD-9 and ICD-10 codes and compared them between Somali and non-Somali populations in Olmsted County, Minnesota utilizing the Rochester Epidemiology Project medical records-linkage infrastructure for the years 2000-2020. Poisson regression models were used to model the rates for each malignancy.

RESULTS

There was a higher incidence and relative risk of liver malignancies among the Somali population versus non-Somali population, but lower relative risk and incidence of the following malignancies: breast, cervical, and melanoma. After direct age-sex adjustment to the United States 2000 Census population, liver was the most common cancer in Somali men, while breast cancer was the most common malignancy in women.

CONCLUSION

Malignancies related to infectious agents such as viral hepatitis have a higher incidence in the Somali immigrant population of Olmsted County. There is a lower incidence of malignancies related to lifestyle factors in this Somali population. Findings of this study may help inform cancer prevention and screening strategies among Somali communities in the United States.

A systematic review and meta-analysis on the relative and attributable risk of Helicobacter pylori infection and cardia and non-cardia gastric cancer

INTRODUCTION

This study aimed to update the association between Helicobacter pylori (H. pylori) infection and gastric cancer (GC).

METHODS

We searched PubMed, Embase, and Cochrane Library from 1990 to December 2021 to identify prospective studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were summarized to validate the relationship between H. pylori infection and GC.

RESULTS

Including 27 studies, findings indicated a strong link between H. pylori and non-cardia gastric cancer (NCGC) in both Europe/North America (OR=5.37, 95%CI:4.39-6.57) and Asia (OR = 2.50, 95%CI:1.89-3.32), and a positive association with cardia gastric cancer (CGC) in Asia (OR = 1.74, 95%CI:1.38-2.19), but an inverse association in European/American populations (OR = 0.64, 95%CI: 0.51 to 0.79). Furthermore, the strength of association was greater in studies that detected H. pylori by immunoblotting versus ELISA, and also in studies testing for H. pylori detection further back in time prior to cancer diagnosis (Ptrend<0.05). Approximately 79% of NCGC in Asia and 87% in Europe/North America, along with 62% of CGC in Asia, could be attributable to H. pylori infection.

CONCLUSIONS

The meta-analysis supports the significant attributable risk of H. pylori infection for GC and underscores the potential impact of targeting H. pylori in GC prevention programs.

PROSPERO REGISTRATION

CRD42021274120.

A prospective cohort study on the association between waterpipe tobacco smoking and gastric cancer mortality in Northern Vietnam

Tobacco consumption, as a worldwide problem, is a risk factor for several types of cancer. In Vietnam, tobacco consumption in the form of waterpipe tobacco smoking is common. This prospective cohort study aimed to study the association between waterpipe tobacco smoking and gastric cancer mortality in Northern Vietnam. A total of 25,619 eligible participants were followed up between 2008 and 2019. Waterpipe tobacco and cigarette smoking data were collected; semi-quantitative food frequency and lifestyle questionnaires were also utilized. Gastric cancer mortality was determined via medical records available at the state health facilities. A Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). During 314,992.8 person-years of follow-up, 55 men and 25 women deaths due to gastric cancer were identified. With never-smokers as the reference, the risk of gastric cancer mortality was significantly increased in participants who were ever-smoking (HR = 2.43, 95% CI = 1.35–4.36). The positive risk was also observed in men but was not significantly increased in women. By types of tobacco use, exclusive waterpipe smokers showed a significantly increased risk of gastric cancer mortality (HR = 3.22, 95% CI = 1.67–6.21) but that was not significantly increased in exclusive cigarette smokers (HR = 1.90, 95% CI = 0.88–4.07). There was a significant positive association between tobacco smoking and gastric cancer death for indicators of longer smoking duration, higher frequency per day, and cumulative frequency of both waterpipe and cigarette smoking. Waterpipe tobacco smoking would significantly increase the risk of gastric cancer mortality in the Vietnamese population. Further studies are required to understand the waterpipe tobacco smoking-driven gastric cancer burden and promote necessary interventions.

Association of mTOR pathway with risk of gastric cancer in male smoker with potential prognostic significance

Aberrant expression of mTOR signaling pathway is significantly associated with gastric cancer. However, the effect of smoking on mTOR expression and its downstream signaling molecules in gastric cancer has not been explored. Our study aims to investigate the effect of smoking on p-mTOR and its correlation with various downstream targets and survival of the smoker and never-smoker in advanced gastric cancer patients. Forty-one smokers and 41 never-smokers patient sample with the advanced gastric carcinoma were chosen for this study. Immunohistochemistry and western blot analysis were performed to check the expression of p-mTOR and its downstream targets. The correlation of p-mTOR with its downstream targets was analyzed by linear regression analysis in Graph Pad Prism software. Survivability analysis was examined by Kaplan-Meier method with log rank test in SPSS. High expression of p-mTOR and its downstream targets were observed in advanced gastric cancer smoker patients as compared to never-smokers by immunohistochemistry and western blot analysis. Results revealed that over expressed p-mTOR in smoker patients were positively correlated with its downstream targets (P < 0.05) and poor survival (P = 0.034). Over expression of p-mTOR in gastric cancer male smoker patients had the worse outcome.

Clinicopathological Characteristics and Incidence of Gastric Cancer in Eastern India: A Retrospective Study

PURPOSE

To study the association of gastric cancer with various clinicopathological traits in eastern India which can be used as an important factor for further analysis, understanding of the diseases and amelioration of patients.

METHODS

The retrospective study includes the patients who underwent subtotal or total gastrectomy from surgical oncology department of Chittaranjan National Cancer Institute (hospital) of West Bengal, India between 2014 and 2018. The study includes 751 gastric cancer patients from Chittaranjan National Cancer Institute. We used electronic hospital records to collect data on various clinical parameters and other information. We used Microsoft Office Excel 2007 spreadsheets for the statistical analyses.

RESULTS

Incidence of gastric cancer is associated with mid age (40-59 years) group male patients and lymph node metastasis. Frequency of gastric cancer is highest in the antrum (42.21%). Of the mid age group gastric cancer patients, 35.02% were having much high risk of developing diffused type of adenocarcinoma (P < 0.00001). Tobacco intake in form of smoking was found as an important risk factor in gastric cancer development with risk ratio and odds ratio of 1.18 and 3.14 respectively.

CONCLUSION

Collectively, the results of the present study confirm that incidence of diffused type of gastric cancer is increasing as an alarming rate in mid age group male patients and tobacco intake in the form of smoking as an independent risk factor for this type of cancer in eastern India. This result can be used to manage gastric carcinoma in future prospective clinical studies and in patient's improvement.

Different Incidence of Early-Onset Gastric Carcinoma Depending on Ethnicity: Preliminary Results of a Hospital in Liangshan

Background

In China, the incidence of cancer has significantly decreased over the last two decades. In contrast, the incidence of gastric carcinoma (GC) has risen in young patients.

Methods

We reevaluated the histopathological results of 4,353 endoscopic gastroscopies from the Department of Pathology at No 1 Hospital of Liangshan. The ethnic groups Han and Yi were almost equally distributed in this cohort. Over a five-year period, 1407 GC were diagnosed.

Results

In 171 of these cases (12%), the patients were ≤40 years old (early-onset GC, EOGC). Out of this cohort, 9 patients were aged ≤25 years. 54% of these patients were male and showed marked predominance (92%) of the Yi-minority. Using the classification of Lauren, 103 GC (60%) were of diffuse type, 27 (16%) of intestinal type, and 41 (24%) of mixed type. In the remaining 1,236 cases of patients ≥41 years (88%), 1,014 patients (82%) belonged to the Yi-minority. Helicobacter pylori (HP) were found in 46% of all cases. Familial clustering was found in 14 patients (18%; in first degree relatives, 12%, and in second degree relatives, 6%). Follow-up was not possible.

Conclusion

This study demonstrates the unequal manifestation of EOGC within the two ethnic groups of Han and Yi. However, familial clustering was infrequent. Further investigations are necessary to discover relevant risk factors apart from hereditary predisposition.

Smoking, Helicobacter Pylori Serology, and Gastric Cancer Risk in Prospective Studies from China, Japan, and Korea

Smoking is an established risk factor for gastric cancer development. In this study, we aimed to assess prospectively the association of smoking with gastric cancer risk in 1,446 non-cardia gastric cancer cases and 1,796 controls from China, Japan, and Korea with consideration of Helicobacter pylori infection as a potential effect modifier. Applying logistic regression models stratified by study and adjusted for age and sex we found that current, but not former, smoking was significantly associated with gastric cancer risk [OR = 1.33; 95% confidence interval (CI), 1.07-1.65]. However, the association was significant only in H. pylori sero-positive individuals determined by 3 different sero-markers: overall sero-positivity, sero-positivity to the onco-protein CagA, and sero-positivity to the gastric cancer associated sero-marker HP0305 and HP1564. Specifically, a significant interaction was found when stratifying by HP0305/HP1564 (P _interaction = 0.01) with a 46% increased risk of gastric cancer among HP0305/HP1564 sero-positive current smokers (95% CI, 1.10-1.93) as opposed to no increased gastric cancer risk among HP0305/HP1564 sero-negative current smokers (OR = 0.93; 95% CI, 0.65-1.33). We confirmed that current smoking is associated with an increased gastric cancer risk, however, only among individuals that are simultaneously sero-positive for the leading causal factor for gastric cancer, H. pylori.

The epidemiology of Helicobacter pylori infection in Europe and the impact of lifestyle on its natural evolution toward stomach cancer after infection: A systematic review

BACKGROUND

Helicobacter pylori is a recognized cause of stomach cancer, but only a fraction of infected subjects develop cancer. This systematic review 1, summarizes the prevalence of infection with this bacterium in Europe; and 2, reviews the possible impact of particular lifestyles in progression from infection to stomach cancer.

MATERIALS AND METHODS

A systematic literature search was conducted in two databases by two independent investigators. Studies describing prevalence of infection among European healthy adult populations and worldwide studies analyzing the impact of lifestyle factors in association with H. pylori on stomach cancer risk were included.

RESULTS

Variable H. pylori infection prevalence was observed depending on region and study period. The lowest infection prevalences were found in Northern Europe, while the highest were in Eastern and Southern Europe, up to 84% in Portugal and Poland. Studies on smoking, salt, and meat consumption demonstrated increased risks of developing stomach cancer among H. pylori-infected individuals, while studies relating the intake of fruit, vegetables, and vitamins demonstrated decreased risks, but the levels of significance differed importantly between studies. No significant interaction could be found for alcohol consumption or physical activity.

CONCLUSIONS

Recent data showed remaining high H. pylori infection rates in several European regions. This systematic review suggests that a number of correctable lifestyle factors could impact the disease progression toward H. pylori-associated stomach cancer. However, additional research is required to determine the potential role of targeted interventions in reducing stomach cancer development after H. pylori infection.

Smoking Status and Gastric Cancer Risk: An Updated Meta-Analysis of Case-Control Studies Published in the past Ten Years

Background

A meta-analysis of published studies was performed in order to clarify the risk of gastric cancer associated with cigarette smoking status.

Methods

Eligible studies were all the case-control studies investigating an association between smoking status and gastric cancer published from January 1, 1997, until June 30, 2006. In order to evaluate the quality of the published data, a qualitative scoring of papers was applied. The principal outcome measure was the odds ratio for the risk of gastric cancer associated with the smoking status using a random effects model. Cigarette smoking status was assessed in two ways: ever (current and ex) versus never smokers; current versus never smokers.

Results

We found a statistically significant result for the association between ever smoking status and gastric cancer risk (OR = 1.48; 95% CI, 1.28–1.71), considering 14,442 cases and 73,918 controls. Moreover, we found an odds ratio of 1.69 for current smoker status in comparison to never smokers (95% CI, 1.35–2.11). Considering only high quality studies, the odds ratio increased by 43% for gastric cancer risk in ever smokers (OR = 1.43; 95% CI, 1.24–1.66; Q = 378.60, P <0.00001; I2 = 90%) and by 57% in current smokers (OR = 1.57; 95% CI, 1.24–2.01). We also considered separately Caucasians and Asian studies, finding for ever smokers an odds ratio of 1.46 (95% CI, 1.25–1.70; Q = 125.68, P <0.00001; I2 = 82.5%) and of 1.47 (95% CI, 1.13–1.91; Q = 366.77, P <0.00001; I2 = 94%), respectively.

Conclusions

From the results of this quantitative meta-analysis, it appears that cigarette smoking has to be considered an important risk factor. The use of qualitative scoring decreases the magnitude of the relationship both for ever and current smoker exposure by 5–12%. Future studies on this topic need to clarify the biological interaction between environmental factors (such as cigarette smoking) and different polymorphisms on gastric cancer.

Risk of stomach cancer in Aotearoa/New Zealand: A Māori population based case-control study

Māori, the indigenous people of New Zealand, experience disproportionate rates of stomach cancer, compared to non-Māori. The overall aim of the study was to better understand the reasons for the considerable excess of stomach cancer in Māori and to identify priorities for prevention. Māori stomach cancer cases from the New Zealand Cancer Registry between 1 February 2009 and 31 October 2013 and Māori controls, randomly selected from the New Zealand electoral roll were matched by 5-year age bands to cases. Logistic regression was used to estimate odd ratios (OR) and 95% confidence intervals (CI) between exposures and stomach cancer risk. Post-stratification weighting of controls was used to account for differential non-response by deprivation category. The study comprised 165 cases and 480 controls. Nearly half (47.9%) of cases were of the diffuse subtype. There were differences in the distribution of risk factors between cases and controls. Of interest were the strong relationships seen with increased stomach risk and having >2 people sharing a bedroom in childhood (OR 3.30, 95%CI 1.95–5.59), testing for H pylori (OR 12.17, 95%CI 6.15–24.08), being an ex-smoker (OR 2.26, 95%CI 1.44–3.54) and exposure to environmental tobacco smoke in adulthood (OR 3.29, 95%CI 1.94–5.59). Some results were attenuated following post-stratification weighting. This is the first national study of stomach cancer in any indigenous population and the first Māori-only population-based study of stomach cancer undertaken in New Zealand. We emphasize caution in interpreting the findings given the possibility of selection bias. Population-level strategies to reduce the incidence of stomach cancer in Māori include expanding measures to screen and treat those infected with H pylori and a continued policy focus on reducing tobacco consumption and uptake.

A global view on cancer incidence and national levels of the human development index

Socioeconomic factors are associated with cancer incidence through complex and variable pathways. We assessed cancer incidence for all cancers combined and 27 major types according to national human development levels. Using GLOBOCAN data for 184 countries, age-standardized incidence rates (ASRs) were assessed by four levels (low, medium, high, very high) of the Human Development Index (HDI), a composite index of life expectancy, education, and gross national income. A strong positive relationship between overall cancer incidence and HDI level was observed. When comparing the ASR in very high HDI regions with that in low HDI regions, we observed a positive association ranging from 2 to 14 and 2 to 11 times higher in males and females, respectively, depending on the cancer type. Positive dose-response relationships between the ASR and HDI level were observed in both sexes for the following cancer types: lung, pancreas, leukemia, gallbladder, colorectum, brain/nervous system, kidney, multiple myeloma, and thyroid. Positive associations were also observed for testicular, bladder, lip/oral cavity, and other pharyngeal cancers, Hodgkin lymphoma, and melanoma of the skin in males, and corpus uteri, breast, and ovarian cancers and non-Hodgkin lymphoma in females. A negative dose-response relationship was observed for cervical and other pharyngeal cancers and Kaposi sarcoma in females. Although the relationship between incidence and the HDI remained when assessed at the country-specific level, variations in risk within HDI levels were also observed. We highlight positive and negative associations between incidence and human development for most cancers, which will aid the planning of cancer control priorities among countries undergoing human development transitions.

Waterpipe Tobacco Smoking and Gastric Cancer Risk among Vietnamese Men

BACKGROUND

The association of waterpipe tobacco (WPT) smoking with gastric cancer (GC) risk was suggested.

METHODS

A hospital-based case-control study was conducted to examine the association of WPT with GC risk among Vietnamese men, in Hanoi city, during the period of 2003-2011. Newly-diagnosed GC cases (n = 454) and control patients (n = 628) were matched by age (+/- 5 years) and the year of hospitalization. Information on smoking and alcohol drinking habits and diet including salty food intake and fruits/vegetables consumption were obtained by the interview. Maximum likelihood estimates of odds ratios (ORs) and corresponding 95% confidence intervals (Cis) were obtained using conditional logistic regression models.

RESULTS

The group with the highest consumption of citrus fruits showed a significantly low GC risk (OR = 0.6, 95%CI = 0.4-0.8, P for trend = 0.002). However, there was no association of raw vegetable consumption with GC risk. Referring to never smokers, GC risk was significantly higher in current WPT smokers (OR = 1.8, 95%CI = 1.3-2.4), and it was more evident in exclusively WPT smokers (OR = 2.7, 95%CI = 1.2-6.5). GC risk tended to be higher with daily frequency and longer duration of WPT smoking but these trends were not statistically significant (P for trend: 0.144 and 0.154, respectively). GC risk of those who started smoking WPT before the age of 25 was also significantly high (OR = 3.7, 95%CI = 1.2-11.3). Neither cigarette smoking nor alcohol drinking was related to GC risk.

CONCLUSION

The present findings revealed that WPT smoking was positively associated with GC risk in Vietnamese men.

Different Pathophysiology of Gastritis in East and West? A Western Perspective

Background

Gastritis results from multifactorial gastric mucosal injury. Helicobacter pylori (Hp) is the main cause, and associated diseases have typical underlying patterns of gastritis. Gastric ulcer and gastric cancer (GC) develop from chronic atrophic corpus gastritis (CAG) which therefore represents the most important pattern. GC incidences in East Asia are substantially higher than elsewhere, and this should be also reflected by higher prevalences of CAG and characteristic differences in pathophysiology compared to the West.

Summary

The few available comparative studies of gastritis in Eastern and Western patients are summarized. The main pathogenic factors of gastritis are discussed together with their limitations to explain local differences in disease outcome. Emphasis was put to also include less well-established pathogenic host and environmental factors of possible impact.

Conclusions

CAG is more prevalent in East Asian areas with high GC incidences than the West. Geographic heterogeneity of associated diseases is due to differences in Hp prevalence and virulence as well as modulating host and environmental factors. The following may contribute to the higher burden of CAG in the East: ABD type of CagA with vacA s1 and babA2 alleles of Hp, host Lewis(b) expression in sej/sej nonsecretors, H. heilmannii, low parietal cell mass, high sodium and nitrate intake, preferences in vegetable and fruit consumption, cigarette smoking, air pollution, alcohol. Conversely, green tea, nonfermented soy products and rice may confer protective effects. Hp is on the decline, but also in a world cleared from this bacterium, differences in host genetics will continue to modify gastric disease outcome together with maintained customs as part of cultural diversity.

Role of Helicobacter pylori in gastric cancer: Updates

Helicobacter pylori (H. pylori) infection is highly prevalent in human, affecting nearly half of the world’s population; however, infection remains asymptomatic in majority of population. During its co-existence with humans, H. pylori has evolved various strategies to maintain a mild gastritis and limit the immune response of host. On the other side, presence of H. pylori is also associated with increased risk for the development of various gastric pathologies including gastric cancer (GC). A complex combination of host genetics, environmental agents, and bacterial virulence factors are considered to determine the susceptibility as well as the severity of outcome in a subset of individuals. GC is one of the most common cancers and considered as the third most common cause of cancer related death worldwide. Many studies had proved H. pylori as an important risk factor in the development of non-cardia GC. Although both H. pylori infection and GC are showing decreasing trends in the developed world, they still remain a major threat to human population in the developing countries. The current review attempts to highlight recent progress in the field of research on H. pylori induced GC and aims to provide brief insight into H. pylori pathogenesis, the role of major virulence factors of H. pylori that modulates the host environment and transform the normal gastric epithelium to neoplastic one. This review also emphasizes on the mechanistic understanding of how colonization and various virulence attributes of H. pylori as well as the host innate and adaptive immune responses modulate the diverse signaling pathways that leads to different disease outcomes including GC.

Relationship between tobacco, cagA and vacA i1 virulence factors and bacterial load in patients infected by Helicobacter pylori

Background and Aim

Several biological and epidemiological studies support a relationship between smoking and Helicobacter pylori (H. pylori) to increase the risk of pathology. However, there have been few studies on the potential synergistic association between specific cagA and vacA virulence factors and smoking in patients infected by Helicobacter pylori. We studied the relationship between smoking and cagA, vacA i1 virulence factors and bacterial load in H. pylori infected patients.

Methods

Biopsies of the gastric corpus and antrum from 155 consecutive patients in whom there was clinical suspicion of infection by H. pylori were processed. In 106 patients H. pylori infection was detected. Molecular methods were used to quantify the number of microorganisms and presence of cagA and vacA i1 genes. A standardized questionnaire was used to obtain patients’ clinical data and lifestyle variables, including tobacco and alcohol consumption. Adjusted Odds Ratios (OR_adjusted) were estimated by unconditional logistic regression.

Results

cagA was significantly associated with active-smoking at endoscope: OR_adjusted 4.52. Evidence of association was found for vacA i1 (OR_adjusted 3.15). Bacterial load was higher in active-smokers, although these differences did not yield statistical significance (median of 262.2 versus 79.4 copies of H. pylori per cell).

Conclusions

The association between smoking and a higher risk of being infected by a virulent bacterial population and with higher bacterial load, support a complex interaction between H. pylori infection and environmental factors.

Impact of Cigarette Smoking on Cancer Risk in the European Prospective Investigation into Cancer and Nutrition Study

Purpose

Our aim was to assess the impact of cigarette smoking on the risk of the tumors classified by the International Agency for Research on Cancer as causally associated with smoking, referred to as tobacco-related cancers (TRC).

Methods

The study population included 441,211 participants (133,018 men and 308,193 women) from the European Prospective Investigation Into Cancer and Nutrition. We investigated 14,563 participants who developed a TRC during an average follow-up of 11 years. The impact of smoking cigarettes on cancer risk was assessed by the population attributable fraction (AFp), calculated using the adjusted hazard ratios and 95% CI for current and former smokers, plus either the prevalence of smoking among cancer cases or estimates from surveys in representative samples of the population in each country.

Results

The proportion of all TRC attributable to cigarette smoking was 34.9% (95% CI, 32.5 to 37.4) using the smoking prevalence among cases and 36.2% (95% CI, 33.7 to 38.6) using the smoking prevalence from the population. The AFp were above 80% for cancers of the lung and larynx, between 20% and 50% for most respiratory and digestive cancers and tumors from the lower urinary tract, and below 20% for the remaining TRC.

Conclusion

Using data on cancer incidence for 2008 and our AFp estimates, about 270,000 new cancer diagnoses per year can be considered attributable to cigarette smoking in the eight European countries with available data for both men and women (Italy, Spain, United Kingdom, the Netherlands, Greece, Germany, Sweden, Denmark).

Tobacco use is associated with increased recurrence and death from gastric cancer

BACKGROUND

Tobacco use increases the risk of developing gastric cancer. We examined the hypothesis that gastric cancer developing in patients with a history of tobacco use may be associated with increased risk of cancer-specific death after curative surgical resection.

METHODS

From the Memorial Sloan-Kettering Cancer Center Gastric Cancer prospective surgical database, we collected baseline demographic data and tumor characteristics from all patients who had undergone curative resection for gastric cancer between 1995 and 2009 and who had not received pre- or postoperative chemo- or radiotherapy. A smoking history was defined as >100 cigarettes' lifetime use. The primary end point was gastric cancer disease-specific survival (DSS); secondary end points were 5-year disease-free survival (DFS) and overall survival (OS). Gastric cancer-specific hazard was modeled by Cox regression.

RESULTS

A total of 699 eligible patients were identified with a median age of 70 years (range 25-96 years); 410 (59%) were current or previous smokers. Smoking was associated with gastroesophageal junction/cardia tumors and white non-Hispanic ethnicity. Multivariate analysis included the following variables: tumor stage, age, performance status, diabetes mellitus, gender, and tumor location. In this analysis, the hazard ratio for gastric cancer DSS in smokers was 1.43 (95% confidence interval 1.08-1.91, P=0.01). Smoking was also an independent significant risk factor for worse 5-year DFS (hazard ratio 1.46, P=0.007) and OS (hazard ratio 1.48, P=0.003). Among 516 patients for whom tobacco pack-year usage was available, both heavy (≥20 pack-years) and light (<20 pack-years) tobacco use was significantly associated with DSS, DFS, and OS.

CONCLUSIONS

Smoking history appears to be an independent risk factor for death from gastric cancer in patients who have undergone curative surgical resection.

Diverse H. pylori strains, IL-10 promoter polymorphisms with high morbidity of gastric cancer in Hexi area of Gansu Province, China

In Hexi area of Gansu Province, people have a higher susceptibility of gastric cancer than people in the rest area of China. There is substantial geographic variation in the incidence of gastric cancer. In this article, the present author explored the roles of H. pylori infection and IL-10 promoter polymorphisms in development of gastric cancer in this area. A total of 304 participants were admitted to our study, and they were divided into two groups: control group and case group. Blood samples from all subjects were collected for gene extraction using DNA extraction kits. IL-10 polymorphisms were determined by SNaPshot Multiplex. To test H. pylori infection and its typing H. pylori antibody Immunoblotting Kits were used. This research suggested that environmental factor played an important role in the pathogenesis of gastric carcinoma in the area, H. pylori infection increased the risk of gastric cancer (OR = 2.612, 95% CI 1.636-4.170) and subject with H. pylori I-type positive was at significantly higher risk for progression to gastric cancer (OR = 4.712, 95% CI 2.656-8.537). For subjects with the ATA/GCC or GCC/GCC haplotype of the IL-10-1082/-819/-592 polymorphism relative to the ATA/ATA haplotype group, the risk of gastric cancer development was significantly increased. It has been demonstrated that the presence of IL-10-819 C alleles and IL-10-592 C alleles was associated with an increased risk for gastric cancer development in H. pylori-infected patients and IL-10 promoter polymorphisms and H. pylori have a synergistic effect on gastric cancer in Hexi population.

Risk factors for esophageal and gastric cancers in Shanxi Province, China: a case-control study

OBJECTIVE

Smoking and alcohol consumption explain little of the risk for upper-gastrointestinal (UGI) cancer in China, where over half of all cases in the world occur.

METHODS

We evaluated questionnaire-based risk factors for UGI cancers in a case-control study from Shanxi Province, China, including 600 esophageal squamous cell carcinomas (ESCCs), 599 gastric cardia adenocarcinomas (GCAs), 316 gastric noncardia adenocarcinomas (GNCAs), and 1514 age- and gender-matched controls.

RESULTS

Ever smoking and ever use of any alcohol were not associated with risk of UGI cancer; only modest associations were observed between ESCC risk and highest cumulative smoking exposure, as well as GNCA risk and beer drinking. While several associations were noted for socioeconomic and some dietary variables with one or two UGI cancers, the strongest and most consistent relations for all three individual UGI cancers were observed for consumption of scalding hot foods (risk increased 150-219% for daily vs. never users) and fresh vegetables and fruits (risk decreased 48-70% for vegetables and 46-68% for fruits, respectively, for high vs. low quartiles).

CONCLUSION

This study confirms the minor role of tobacco and alcohol in UGI cancers in this region, and highlights thermal damage as a leading etiologic factor.

Interactions between CagA and smoking in gastric cancer

AIM: To examine the interactions between cytotoxin-associated gene (CagA) positive Helicobacter pylori infection and smoking in non-cardiac gastric cancer.

METHODS: A case-control study (257 cases and 514 frequency-matched controls) was conducted from September 2008 to July 2010 in Xi’an, China. Cases were newly diagnosed, histologically confirmed non-cardiac cancer. Controls were randomly selected from similar communities to the cases and were further matched by sex and age (± 5 years). A face-to-face interview was performed by the investigators for each participant. Data were obtained using a standardized questionnaire that included questions regarding known or suspected lifestyle and environmental risk factors of gastric cancer. A 5 mL sample of fasting venous blood was taken. CagA infection was serologically detected by enzyme-linked immunosorbent assays.

RESULTS: Smoking and CagA infection were statistically significant risk factors of non-cardiac cancer. CagA was categorized in tertiles, and the odds ratio (OR) was 12.4 (95% CI: 6.1-20.3, P = 0.003) for CagA after being adjusted for confounding factors when the high-exposure category was compared with the low-exposure category. Smokers had an OR of 5.4 compared with subjects who never smoked (95% CI: 2.3-9.0, P = 0.002). The OR of non-cardiac cancer was 3.5 (95% CI: 1.8-5.3) for non-smokers with CagA infection, 3.5 (95% CI: 1.9-5.1) for smokers without CagA infection, and 8.7 (95% CI: 5.1-11.9) for smokers with CagA infection compared with subjects without these risk factors. After adjusting for confounding factors, the corresponding ORs of non-cardiac cancer were 3.2 (95% CI: 1.5-6.8), 2.7 (95% CI: 1.3-4.9) and 19.5 (95% CI: 10.3-42.2), respectively. There was a multiplicative interaction between smoking and CagA, with a synergistic factor of 2.257 (Z = 2.315, P = 0.021).

CONCLUSION: These findings support a meaningful interaction between CagA and smoking for the risk of gastric cancer which may have implications for its early detection.

Helicobacter pylori and gastric cancer: factors that modulate disease risk

Helicobacter pylori is a gastric pathogen that colonizes approximately 50% of the world's population. Infection with H. pylori causes chronic inflammation and significantly increases the risk of developing duodenal and gastric ulcer disease and gastric cancer. Infection with H. pylori is the strongest known risk factor for gastric cancer, which is the second leading cause of cancer-related deaths worldwide. Once H. pylori colonizes the gastric environment, it persists for the lifetime of the host, suggesting that the host immune response is ineffective in clearing this bacterium. In this review, we discuss the host immune response and examine other host factors that increase the pathogenic potential of this bacterium, including host polymorphisms, alterations to the apical-junctional complex, and the effects of environmental factors. In addition to host effects and responses, H. pylori strains are genetically diverse. We discuss the main virulence determinants in H. pylori strains and the correlation between these and the diverse clinical outcomes following H. pylori infection. Since H. pylori inhibits the gastric epithelium of half of the world, it is crucial that we continue to gain understanding of host and microbial factors that increase the risk of developing more severe clinical outcomes.

Helicobacter pylori, nutrition and smoking interactions: their impact in gastric carcinogenesis

Gastric cancer (GC) is the result of a long multi-step and multifactorial process involving possible interactions between Helicobacter pylori infection, environmental exposures and host genetic susceptibility. Interactions between H. pylori infection, tobacco smoking and dietary antioxidants are biologically plausible. Positive interactions between risk factors imply that, in certain subgroups of the population, the risk of GC associated with simultaneous exposure to these factors is higher than that in the rest of the population, and these subgroups have to be the target for preventive measures. Using PubMed, we reviewed all studies published in English up to December 2008 carried out in humans on interactions between H. pylori infection and smoking exposure and between H. pylori infection and dietary factors in gastric carcinogenesis. Although relatively few epidemiological studies have evaluated the effect of the interaction between smoking and H. pylori infection on GC risk, there is a suggestion of a positive interaction between the two factors. In contrast, evidence suggests a negative interaction between dietary antioxidants and H. pylori infections on GC risk. The potential protective effect of dietary antioxidants such as vitamins C and E and beta-carotene seems to be stronger in those infected by H. pylori, even though results are inconsistent. In Asian populations, subjects infected by H. pylori and with high dietary salt intake may have a higher risk of GC than subjects without H. pylori infection and with a low salt intake. The risk of GC associated with red meat, processed meat or endogenous formation of nitrosamines appears to only be observed in subjects infected by H. pylori. More and larger epidemiological studies, mainly prospective studies, are necessary to reach a more definitive conclusion on these interactions.

Stomach cancer risk in gastric cancer relatives: interaction between Helicobacter pylori infection and family history of gastric cancer for the risk of stomach cancer

GOALS

To identify the risk of gastric cancer in first-degree relatives of gastric cancer patients, and to determine if there is an interaction between Helicobacter pylori (H. pylori) infection and family history of gastric cancer in gastric carcinogenesis.

BACKGROUND

It is unclear to what degree a family history of gastric cancer is associated with stomach cancer risk in Korea.

STUDY

From May 2003 to July 2008, 428 gastric cancer patients and 368 controls were included in the analyses. Logistic regression models including age, sex, family history of gastric cancer, residency during childhood, smoking, monthly income, spicy food diet and H. pylori status were evaluated to estimate the odds ratios (ORs) of developing gastric cancer.

RESULTS

Adjusted OR for gastric cancer increased 3-fold for subjects reporting first-degree relatives with gastric cancer [OR 2.85, 95% confidence interval (CI): 1.83-4.46]. The association was strong in the 40 to 59 years age group (OR 4.00, 95% CI: 2.06-7.76), and became weaker in subjects older than 60 years of age (OR 1.81, 95% CI: 0.95-3.46). Compared with the uninfected subjects without a family history, subjects with both a family history and H. pylori infection had a 5-fold increased risk (OR 5.32, 95% CI: 2.76-10.25).

CONCLUSIONS

After adjusting for environmental factors and H. pylori infection, a family history of gastric cancer remained independently associated with gastric cancer. The interaction between H. pylori infection and family history of gastric cancer might be a rationale for H. pylori eradication in the gastric cancer relatives as a strategy to prevent gastric cancer.

Glutathione-S-transferase (GSTM1, GSTT1) and the risk of gastrointestinal cancer in a Korean population

AIM: To evaluate the association of glutathione S-transferase mu (GSTM1) and glutathione S-transferase theta (GSTT1) null genotypes with the risk of gastric cancer (GC) and colorectal cancer (CRC) in a South Korean population.

METHODS: We conducted a population-based, large-scale case-control study including 2213 GCs, 1829 CRCs, and 1699 controls. Null and non-null genotypes of GSTM1 and GSTT1 were determined using real-time PCR.

RESULTS: The null genotypes of GSTM1 and GSTT1 were not significantly associated with elevated risk of gastric (OR = 1.070, 95% CI = 0.935-1.224; OR = 1.101, 95% CI = 0.963-1.259, respectively) or colorectal cancer (OR = 1.065, 95% CI = 0.923-1.228; OR = 1.041, 95% CI = 0.903-1.200, respectively). The frequency of the combined null GST genotype was not different between the two cancer groups and controls. Moreover, smoking, drinking, and age did not modify the association between these genotypes and the risk of gastric or colorectal cancer.

CONCLUSION: GSTM1 and GSTT1 null genotypes were not associated with increased risk of GC or CRC in Koreans.

LTA 252GG and GA genotypes are associated with diffuse-type noncardia gastric cancer risk in the Japanese population

BACKGROUND

There are limited numbers of reports on the association of lymphotoxin-alpha (LTA) genotypes with gastric cancer.

METHODS

A nested case-control study was carried out in the longitudinal cohort of atomic bomb survivors using stored sera before diagnosis (mean, 2.3 years) and blood cells. Enrolled were 287 cases with noncardia gastric cancer of diffuse and intestinal types and three controls per case selected from cohort members matched on age, gender, city, and time and type of serum storage and counter-matched on radiation dose.

RESULTS

LTA 252GG and GA genotypes were associated with the prevalence of Helicobacter pylori IgG seropositivity and higher antibody titer against H. pylori cytotoxin-associated gene A (CagA) protein in controls and they were an independent risk factor for noncardia gastric cancer of diffuse type (RR = 2.8 (95% CI: 1.3-6.3), p = .01, and RR = 2.7 (95% CI: 1.5-4.8), p < .001), but not for intestinal type, after adjusting for H. pylori IgG seropositivity, CagA antibody titers, chronic atrophic gastritis, smoking, and radiation dose. Cessation of smoking (RR = 0.4 (95% CI: 0.2-0.7), p < .001) and never smoking (RR = 0.4 (95% CI: 0.3-0.6), p < .001) were both protective for future noncardia gastric cancer. Radiation dose was associated with noncardia gastric cancer in subjects with both the LTA 252G-allele and never smoking/quit smoking histories (RR = 3.8 (95% CI: 1.7-5.9), p = .009).

CONCLUSION

The LTA 252 genotype is associated with noncardia gastric cancer of diffuse type in Japan and interacted with radiation dose.

High-risk population for gastric cancer development based on serum pepsinogen status and lifestyle factors

BACKGROUND

Gastric atrophy is a major risk factor for non-cardiac gastric cancer. Serum pepsinogen status could identify people at high-risk for gastric cancer development during our previous cohort study. However, lifestyle-related factors may additionally affect this risk.

MATERIALS AND METHODS

A total of 6983 Japanese were followed up by annual endoscopy in the previous study, and 43 cases of gastric cancer including two cardiac cancers developed. In most subjects, the body length and weight were measured and a questionnaire was applied to gather information regarding life habits. The risk of non-cardiac gastric cancer development during surveillance was re-analyzed based on serum pepsinogen, sex, age, body mass index (BMI), alcohol, and smoking habit.

RESULTS

A total of 6158 subjects with 37 non-cardiac gastric cancer development (male/female = 4259/1899, mean age = 49.0, mean follow-up period = 4.79 years) were entered into analysis. In a multivariate analysis, old age (by 10 years; (odds ratio) OR, 2.8; p < .001), alcohol (weekly; OR, 2.4; p = .03), smoking (current; OR, 5.6; p = .006 and past; OR, 3.9; p = .04), and pepsinogen status ("atrophic"; OR, 6.2; p < .001) were independent risk factors, whereas BMI was not. The annual incidence of gastric cancer was 1.2% in the older subjects aged > or = 60 years with "atrophic" pepsinogen status. Moreover, it was as high as 2.9% when they had both alcohol and current smoking habits.

CONCLUSIONS

Old age, alcohol, and smoking habits additionally promoted the risk for gastric cancer in subjects with gastric atrophy.

Cancer mortality in chinese populations surrounding an alloy plant with chromium smelting operations

This report is a further characterization of data from an ecological cancer mortality study of a population (about 10,000) exposed to groundwater contaminated by hexavalent chromium [Cr(VI)] up to 20 mg/L near JinZhou City in the LiaoNing Province of China between 1960 and 1978. Prior reports showed an elevation in all-cancer mortality from 1970 to 1978 averaged across five agricultural villages with Cr(VI) in groundwater relative to average cancer rates for the district and province. The current study compares the cancer rates during the same time period for the same five exposed villages to those of four nearby areas with no Cr(VI) in groundwater. The use of a local comparison group is considered superior to the use of district or province averages because of the expected improved similarity among unmeasured covariates in nearby areas. The average lung-, stomach-, and all-cancer mortality rates for the three agricultural villages without Cr(VI) in groundwater were not statistically different from those of the five agricultural villages with Cr(VI) in groundwater. Also, three surrogate measures of village drinking-water Cr(VI) dose did not significantly correlate with cancer mortality rates in the five exposed villages. Further, the industrial town in which the Cr(VI) source was located had different demographics and a different pattern of stomach and lung cancers compared to the adjacent agricultural villages, regardless of Cr(VI) groundwater exposure. The results of other local investigations on cancer mortality and genotoxicity in the exposed populations are reviewed. The overall findings in the studied population do not indicate a dose-response relationship or a coherent pattern of association of lung-, stomach-, or all-cancer mortality with exposure to Cr(VI)-contaminated groundwater.

Population-based prospective study of the combined influence of cigarette smoking and Helicobacter pylori infection on gastric cancer incidence: the Hisayama Study

The authors assessed the separate and joint influences of cigarette smoking and Helicobacter pylori infection on the development of gastric cancer in a population-based prospective study. A total of 1,071 Japanese men aged > or =40 years were followed up prospectively for 14 years (1998-2002). Compared with that for current nonsmokers, the multivariate-adjusted hazard ratios of gastric cancer for smokers of 1-9, 10-19, and > or =20 cigarettes per day were 1.36 (95% confidence interval (CI): 0.50, 3.71), 1.93 (95% CI: 1.01, 3.67), and 1.88 (95% CI: 1.02, 3.43), respectively. The risk of gastric cancer increased steeply for subjects who had both a smoking habit and H. pylori infection compared with those who did not have both risk factors (hazard ratio = 11.41, 95% CI: 1.54, 84.67). If causal, the estimated population attributable fraction of gastric cancer for cigarette smoking was approximately half that for H. pylori infection (28.4% vs. 56.2%). The overlap of the population attributable fractions for the 2 factors was 49.6%. Findings suggest that cigarette smoking and H. pylori infection are significant risk factors for gastric cancer in Japanese men, and the magnitude of their combined influence is considerable.

Smoking and gastric cancer: systematic review and meta-analysis of cohort studies

OBJECTIVE

We conducted a systematic review of studies addressing the relation between cigarette smoking and gastric cancer to estimate the magnitude of the association for different levels of exposure and cancer locations.

METHODS

Published cohort, case-cohort, and nested case-control studies were identified through PubMed, Scopus, and Web of Science searches, from inception to July 2007. Relative risk (RR) estimates referring to the comparison of two categories of exposure (e.g., current smokers vs. never smokers) were combined using a random effects model. Generalized least squares regression was used for trend estimation. Heterogeneity was quantified using the I (2) statistic.

RESULTS

Forty-two articles were considered for the systematic review. Comparing current smokers with never smokers: the summary RR estimates were 1.62 in males (95% CI: 1.50-1.75; I (2) = 46.0%; 18 studies) and 1.20 in females (95% CI: 1.01-1.43; I (2) = 49.8%; nine studies); the RR increased from 1.3 for the lowest consumptions to 1.7 for the smoking of approximately 30 cigarettes per day in the trend estimation analysis; smoking was significantly associated with both cardia (RR = 1.87; 95% CI: 1.31-2.67; I (2) = 73.2%; nine studies) and non-cardia (RR = 1.60; 95% CI: 1.41-1.80; I (2) = 18.9%; nine studies) cancers.

CONCLUSION

Our study provides solid evidence to classify smoking as the most important behavioral risk factor for gastric cancer.

Smoking, alcohol and gastric cancer risk in Korean men: the National Health Insurance Corporation Study

We investigated the risk of gastric cancer by subsite in relation to cigarette smoking and alcohol in a large population-based cohort of 669 570 Korean men in an insurance plan followed for an average 6.5 years, yielding 3452 new cases of gastric cancer, of which 127 were cardia and upper-third gastric cancer, 2409 were distal gastric cancer and 1007 were unclassified. A moderate association was found between smoking, cardia and upper-third (adjusted relative risk (aRR) 2.2; 95% confidence interval (CI) 1.4-3.5) and distal cancers (aRR=1.4; 95% CI=1.3-1.6). We also found a positive association between alcohol consumption and distal (aRR=1.3; 95% CI=1.2-1.5) and total (aRR=1.2; 95% CI=1.1-1.4) gastric cancer. Combined exposure to high levels of tobacco and alcohol increased the risk estimates further; cardia and upper-third gastric cancers were more strongly related to smoking status than distal gastric cancer.British Journal of Cancer (2007) 97, 700-704. doi:10.1038/sj.bjc.6603893 www.bjcancer.com Published online 17 July 2007.

Diet, H pylori infection and gastric cancer: evidence and controversies

Despite decreasing incidence and mortality rates, gastric cancer (GC) still remains the fourth most common cancer and the second most common cause of cancer-related deaths worldwide. Due to the limited treatment options, at present, prevention is likely to be the only effective means of controlling this disease. The success of a prevention strategy depends upon the understanding of etiological and pathogenic mechanisms underlying gastric carcinogenesis. The etiology of GC is multi-factorial, however, in the recent years, mounting evidence suggests that environmental factors play a key role. The most important environmental factors implicated in the pathogenesis of GC are diet and H pylori infection. Thus, modifications in lifestyle and dietary habit associated with eradication of H pylori infection could hypothetically represent the most promising potential targets for GC prevention. In this review we will address the evidence and the controversies on the role of these agents in non-cardia GC by focusing on retrospective and prospective observational studies and interventional trials.

Red wine and green tea reduce H pylori- or VacA-induced gastritis in a mouse model

AIM: To investigate whether red wine and green tea could exert anti-H pylori or anti-VacA activity in vivo in a mouse model of experimental infection.

METHODS: Ethanol-free red wine and green tea concentrates were administered orally as a mixture of the two beverages to H pylori infected mice, or separately to VacA-treated mice. Gastric colonization and gastric inflammation were quantified by microbiological, histopathological, and immunohistochemical analyses.

RESULTS: In H pylori-infected mice, the red wine and green tea mixture significantly prevented gastritis and limited the localization of bacteria and VacA to the surface of the gastric epithelium. Similarly, both beverages significantly prevented gastric epithelium damage in VacA-treated mice; green tea, but not red wine, also altered the VacA localization in the gastric epithelium.

CONCLUSION: Red wine and green tea are able to prevent H pylori-induced gastric epithelium damage, possibly involving VacA inhibition. This observation supports the possible relevance of diet on the pathological outcome of H pylori infection.

Polyphenols reduce gastritis induced by Helicobacter pylori infection or VacA toxin administration in mice

Helicobacter pylori colonizes the human gastric mucosa, causing inflammation that leads to atrophic gastritis, and it can cause peptic ulcer and gastric cancer. We show that polyphenol administration to mice experimentally infected by H. pylori or treated with VacA toxin can limit gastric epithelium damage, an effect that may be linked to VacA inhibition.

Environment as a Critical Factor for the Pathogenesis and Outcome of Gastrointestinal Disease: Experimental and Human Inflammatory Bowel Disease and Helicobacter-Induced Gastritis

Environmental factors play an important role in the manifestation, course, and prognosis of diseases of the gastrointestinal tract such as inflammatory bowel disease (IBD) and Helicobacter pylori-induced gastritis. These two disease complexes were chosen for a discussion of the contribution of environmental factors to the disease outcome in humans and animal models. Dissecting complex diseases like IBD and Helicobacter-induced gastritis has shown that the outcome of disease depends on the allelic constellation of a host and the microbial and physical environments. Host alleles predisposing to a disease in one genomic and/or environmental milieu may not be deleterious in other constellations; on the other hand, microbes can have different effects in different hosts and under different environmental conditions. The impact of the complex interaction between host genetics and environmental factors, particularly microflora, also underlines the importance of a defined genetic background and defined environments in animal studies and is indicative of the difficulties in analyzing complex diseases in humans.

Cigarette smoking and the risk of gastric cancer: a pooled analysis of two prospective studies in Japan

To examine the association between cigarette smoking and the risk of gastric cancer, we conducted a pooled analysis of 2 population-based prospective cohort studies in rural northern Japan. Cohort 1 included 9,980 men (>or=40 years old) and Cohort 2 included 19,412 men (40-64 years old). The subjects completed a self-administered questionnaire on cigarette smoking and other health habits. We identified 228 cases of gastric cancer among Cohort 1 subjects (9 years of follow-up with 74,073 person-years) and 223 among Cohort 2 subjects (7 years of follow-up with 141,675 person-years). From each cohort, we computed the relative risk (RR) and 95% confidence interval (CI) of gastric cancer associated with smoking using a Cox regression analysis and pooled these estimates to obtain summary measures. The pooled multivariate RRs (95% CIs) for current smokers and past smokers compared to subjects who had never smoked were 1.84 (1.39-2.43) and 1.77 (1.29-2.43), respectively. The higher number of cigarettes smoked per day among current smokers was associated with a linear increase in risk (trend p < 0.05). The significant increase in risk for past smokers remained for up to 14 years after cessation. An increased risk was noted for cancer of the antrum but not for cardia or body lesions. The risk was increased for both differentiated and nondifferentiated histologic subtypes. Our findings support the hypothesis that cigarette smoking is a risk factor for gastric cancer.

Helicobacter pylori and gastric cancer prevention is possible

Epidemiological data gathered during the past few years have shown an association between Helicobacter pylori infection and gastric carcinoma. This association is considered to be causal because of its biological plausibility and the existence of an animal model, even though the positive consequences of eradication on cancer prevention have not yet been definitely proven. The limited proportion of H. pylori infected subjects who develop a gastric cancer can be explained by host factors (certain alleles of IL-1beta) and bacterial factors (cag positive strains), and to a lesser extent by environmental factors (diet). Arguments in favor of the prevention of gastric carcinoma by eradicating H. pylori are now stronger than before, given the availability of simple and accurate diagnostic tests (serology) and treatment follow-up (urea breath test), as well as a 7-day treatment which is usually sufficient for eradication.

Helicobacter pylori infection and gastric cancer: facing the enigmas

At an individual level Helicobacter pylori was associated with the occurrence of gastric cancer but in some African and Asian countries its prevalence runs with low gastric cancer rates, the so-called African and Asian enigmas. We assessed whether the association between gastric cancer and H. pylori prevalence at an area level is modified by the level of exposure to fruits and vegetables, alcohol or tobacco. Regression models were fitted to data from 58 countries using as dependent variable log transformed gastric cancer rates and as independent covariables the H. pylori prevalence, fruits and vegetables consumption, cigarette smoking, alcohol intake and interaction terms. The levels of alcohol consumption or cigarette smoking modified the association between gastric cancer and H. pylori infection. Models including H. pylori prevalence, alcohol consumption, cigarette smoking and the interaction terms H. pylori x alcohol or H. pylori x tobacco were used to compute gastric cancer incidence multiplying regression coefficients by a H. pylori prevalence of 85% (the approximate median in African countries) and the median figures observed in each continent for alcohol and tobacco availability. The expected gastric cancer incidence per 100,000 would be 5.7 assuming the alcohol and tobacco availability in African countries, 7.0 in Asia and Oceania, 16.0 in America and 26.0 in Europe. The interaction between H. pylori and cigarette or alcohol consumption may contribute to further explain the international variation in gastric cancer and the so-called African and Asian enigmas.

Smoking and the risk of gastric cancer in the European Prospective Investigation Into Cancer and Nutrition (EPIC)

Smoking has recently been recognised as causally associated with the development of gastric cancer (GC). However, evidence on the effect by sex, duration and intensity of smoking, anatomic subsite and cessation of smoking is limited. Our objective was to assess the relation between tobacco use and GC incidence in the European Prospective Investigation into Cancer and Nutrition (EPIC). We studied data from 521,468 individuals recruited from 10 European countries taking part in the EPIC study. Participants completed lifestyle questionnaires that included questions on lifetime consumption of tobacco and diet in 1991-1998. Participants were followed until September 2002, and during that period 305 cases of stomach cancer were identified. After exclusions, 274 were eligible for the analysis, using the Cox proportional hazard model. After adjustment for educational level, consumption of fresh fruit, vegetables and preserved meat, alcohol intake and body mass index (BMI), there was a significant association between cigarette smoking and gastric cancer risk: the hazard ratio (HR) for ever smokers was 1.45 (95% confidence interval [CI] = 1.08-1.94). The HR of current cigarette smoking was 1.73 (95% CI = 1.06-2.83) in males and 1.87 (95% CI = 1.12-3.12) in females. Hazard ratios increased with intensity and duration of cigarette smoked. A significant decrease of risk was observed after 10 years of quitting smoking. A preliminary analysis of 121 cases with identified anatomic site showed that current cigarette smokers had a higher HR of GC in the cardia (HR = 4.10) than in the distal part of the stomach (HR = 1.94). In this cohort, 17.6 % (95% CI = 10.5-29.5 %) of GC cases may be attributable to smoking. Findings from this large study support the causal relation between smoking and gastric cancer in this European population. Stomach cancer should be added to the burden of diseases caused by smoking.

Role of Helicobacter pylori CagA+ strains and risk of adenocarcinoma of the stomach and esophagus

Infection with Helicobacter pylori (H. pylori), especially CagA+ strains, has been associated with an increased risk of noncardia gastric adenocarcinoma. The relationship with junctional cancer (adenocarcinomas of the esophagus and gastric cardia combined) has not been adequately investigated, although some studies have reported a reduced risk associated with H. pylori and CagA seroseropositivity. We investigated this question in a subset of cases and controls from a recently completed, large population-based case-control study of gastric and esophageal adenocarcinomas in Los Angeles County. Using established antigen-specific ELISAs, serum IgG antibodies to H. pylori whole-cell antigens (Helico-G) and CagA were measured in population controls (n = 356) and patients with incident esophageal adenocarcinoma (n = 80), gastric cardia cancer (n = 87) or distal gastric cancers (noncardia gastric adenocarcinoma) (n = 127). After controlling for demographic characteristics (age, gender, race, birthplace, education), smoking and body mass index, seropositivity for H. pylori was associated with a statistically significant increased risk of distal gastric cancer (adjusted odds ratio [OR] = 1.85, 95% confidence interval [CI] = 1.03, 3.32) but the risk of junctional cancer was not increased (adjusted OR = 1.26, 95% CI = 0.82, 1.94). The risk of junctional cancer was not changed when CagA and H. pylori were both considered, but the risk of distal gastric cancer was further increased. Subjects who were seropositive for both CagA and H. pylori compared to those who were seronegative for H. pylori showed a risk of 2.20 (95% CI = 1.13, 4.26) for distal gastric cancer and 0.86 (95% CI = 0.47, 1.59) for junctional cancer. Although tests for interaction between smoking and H. pylori were not statistically significant for junctional or distal gastric cancers, risk for both tumor types tended to be higher among current smokers who were also H. pylori seropositive. In conclusion, we find no evidence that infection with CagA+ strains of H. pylori reduces risk of esophageal and gastric cardia adenocarcinoma in this population. Our findings confirm the positive association between risk of distal gastric cancer and infection with H. pylori infection, especially CagA+ strains.

Statistical model of the interactions between Helicobacter pylori infection and gastric cancer development

BACKGROUND

The bacterium Helicobacter pylori is associated with a number of gastrointestinal diseases, such as gastric ulcer, duodenal ulcer and gastric cancer. Several histological changes may be observed during the course of infection; some may influence the progression towards cancer. The aim of this study was to build a statistical model to discover direct interactions between H. pylori and different precancerous changes of the gastric mucosa, and in what order and to what degree those may influence the development of the intestinal type of gastric cancer.

METHODS

To find direct and indirect interactions between H. pylori and different histological variables, log-linear analyses were used on a case-control study. To generate mathematically and biologically relevant statistical models, a designed algorithm and observed frequency tables were used.

RESULTS

The results show that patients with H. pylori infection need to present with proliferation and intestinal metaplasia to develop gastric cancer of the intestinal type. Proliferation and intestinal metaplasia interacted with the variables atrophy and foveolar hyperplasia. Intestinal metaplasia was the only variable with direct interaction with gastric cancer. Gender had no effect on the variables examined.

CONCLUSION

The direct interactions observed in the final statistical model between H. pylori, changes of the mucosa and gastric cancer strengthens and supports previous theories about the progression towards gastric cancer. The results suggest that gastric cancer of the intestinal type may develop from H. pylori infection, proliferation and intestinal metaplasia, while atrophy and foveolar hyperplasia interplay with the other histological variables in the disease process.

Cigarette smoking, use of other tobacco products and stomach cancer mortality in US adults: The Cancer Prevention Study II

Cigarette smoking is associated with increased risk of stomach cancer in many studies but there are limited data on this relationship in women and on risk associated with use of tobacco products other than cigarettes. We examined stomach cancer death rates in relation to cigarette smoking in women and use of cigarette, cigar, pipe, or smokeless tobacco in men in a nationwide prospective mortality study in the United States (US). Cohort follow-up from 1982-96 identified 996 and 509 stomach cancer deaths among 467,788 men and 588,053 women, respectively. Cox proportional hazards models were fitted to estimate rate ratios (RR) and 95% confidence intervals (CI) using non-users of tobacco as the referent group. Multivariate-adjusted RRs were the highest for men who currently smoked cigars (RR = 2.29, 95% CI = 1.49-3.51) or cigarettes (RR = 2.16, 95% CI = 1.75-2.67) and both increased with smoking duration. Women who currently (RR = 1.49, 95% CI = 1.18-1.88) or formerly (RR = 1.36, 95% CI = 1.08-1.71) smoked cigarettes were at significantly increased risk, as were men who formerly smoked cigarettes (RR = 1.55, 95% CI = 1.28-1.88), or currently (RR = 1.81, 95% CI = 1.40-2.35) or formerly (RR: 1.57, 95% CI = 1.22-2.03) used more than one type of tobacco. Men who reported a history of chronic indigestion or gastroduodenal ulcer had substantially higher mortality rates associated with current cigarette (RR = 3.45, 95% CI = 2.05-5.80) or cigar (RR = 8.93, 95% CI = 4.02-19.90) smoking, as did men who were current aspirin users. If causal, the estimated proportion of stomach cancer deaths attributable to tobacco use would be 28% in US men and 14% in women. We conclude that prolonged use of tobacco products is associated with increased stomach cancer mortality in men and women. The accumulated evidence from this and other studies support reconsidering stomach cancer as a tobacco-related cancer.

New strategies for the prevention and treatment of Helicobacter pylori infection

Helicobacter pylori infects the stomach of > 50% of the human population worldwide, with higher prevalence in the developing countries. A strict correlation between H. pylori infection and gastroduodenal diseases has been demonstrated, including gastritis, peptic ulcer and gastric cancer. Current therapies against H. pylori consist of an antisecretory plus antibiotics. These therapies are effective in 80 - 90% of the cases; presently, no alternative therapies have been shown to give comparable or better results. There are two main reasons for therapy failure: poor compliance, which results in cure discontinuation, and antibiotic resistance. To overcome the drawbacks inherent to any antibiotic therapy, a prophylactic vaccine seems to be the most reasonable approach. Vaccines have been developed based on data obtained in animal models, a number of which are currently in Phase I clinical trials, in some cases giving encouraging data for safety and immunogenicity. In the absence of any immunological correlate of protection against H. pylori, it will be possible to evaluate the efficacy of these vaccines only in large Phase III clinical trials.

Multifocal atrophic gastritis and gastric carcinoma

Gastric carcinoma remains a major cause of morbidity and mortality worldwide despite its significant decline in recent years. H. pylori infection begins with nonatrophic gastritis, and most individuals continue to have nonatrophic H. pylori gastritis throughout their lifetime. A minority of those with severe antral inflammation will develop a duodenal ulcer, and a few, for unknown reasons, may develop gastric MALT lymphoma. Others, who acquired the H. pylori infection in early childhood, develop progressive multifocal atrophic gastritis with loss of gastric glands. A small proportion of these individuals develop extensive, incomplete (type III) intestinal metaplasia, and an even smaller proportion will progress to dysplasia and intestinal-type gastric carcinoma. H. pylori-associated gastritis is also a risk factor for diffuse-type gastric carcinoma, which is not preceded by atrophy, intestinal metaplasia, or dysplasia. Appropriate screening and preventive measures should be considered in high-risk groups. It is also crucial to identify cofactors such as genetic susceptibility and environmental factors that might interact with H. pylori infection to increase gastric cancer risk. To make an impact on gastric cancer incidence and mortality, serious consideration should be given to early H. pylori eradication in high-risk groups and endoscopic surveillance according to the updated Sydney system in some patients with high-risk preneoplastic lesions, whereas dysplastic lesions should be removed without delay. Studies currently in progress may tell us whether H. pylori eradication can prevent later development of gastric carcinoma and thus eliminate a major cause of mortality worldwide.

Risk of gastric cancer among smokers infected with Helicobacter pylori

Infection with the gastric bacterium Helicobacter pylori (in particular infection with CagA-positive strains) and smoking have been identified as risk factors for the development of gastric cancer. Both risk factors are typically acquired early in life and prevail over decades if not for life. We assessed the individual and joint impact of both risk factors on gastric cancer risk in a population-based case-control study from Germany including 71 patients with histologically verified gastric cancer and 363 patients with colorectal cancer who served as controls. Information on smoking and potential confounding factors was collected by standardized interviews. H. pylori infection was measured serologically by immunoglobulin G antibody titers against H. pylori. In addition, antibodies against the CagA antigen were determined by Western blot. Twenty-seven percent of cases compared with 15% of controls were smokers, and 43% of cases compared with 23% of controls were infected with CagA-positive H. pylori strains. After control for potential confounders, the relative risk of gastric cancer was 2.6 (95% CI 1.2-5.7) for nonsmoking subjects with CagA-positive H. pylori infections and 7.2 (95% CI 2.2-23.6) for smoking subjects with CagA-positive H. pylori infections compared with subjects without these risk factors. The corresponding relative risks for noncardia gastric cancer were 6.1 ( 95% CI 2.3-16.5) and 16.6 (95% CI 4.3-64.2). We conclude that smoking subjects with CagA-positive H. pylori infections have a strongly increased risk of gastric cancer and may be an important group for targeting efforts of prevention and early detection.