Occupational exposures as risk factors for gastric cancer in Italy

A comprehensive update on early gastric cancer: defining terms, etiology, and alarming risk factors

INTRODUCTION

Early gastric cancer (EGC) is a well-defined gastric malignancy that is limited to the mucosa or submucosa, irrespective of lymph node metastasis. At an early stage, gastric cancer often does not cause symptoms until it becomes advanced, and it is a heterogeneous disease and usually encountered in its late stages.

AREA COVERED

This comprehensive review will provide a novel insight into the evaluation of EGC epidemiology, defining terms, extensive etiology and risk factors, and timely diagnosis since prevention is an essential approach for controlling this cancer and reducing its morbidity and mortality.

EXPERT OPINION

The causative manner of EGC is complex and multifactorial. In recent years, researchers have made significant contributions to understanding the etiology and pathogenesis of EGC, and standardization in the evaluation of disease activity. Though the incidence of this cancer is steadily declining in some advanced societies owing to appropriate interventions, there remains a serious threat to health in developing nations. Early detection of resectable gastric cancer is crucial for better patient outcomes.

Gastric cancer mortality rates by occupation and industry among male and female workers aged 25-64 years in Japan

Differences in risk for gastric cancer exist among occupations and industries in Japan. Using a 2015 national dataset, we estimated the mortality rates due to gastric cancer in Japanese male and female workers aged 25-64 yr. Regression models were used to estimate the mortality rate ratios separately for men and women with adjustment for age. The occupation with the highest risk ratio was "Service" in men (2.06, 95% confidence interval: 1.63-2.61) and "Construction and Mining" in women compared with "Sales". For industries, workers in "Mining", "Electricity, Gas, Heat supply and Water", "Fisheries", "Agriculture and Forestry", and "Construction" had a higher mortality risk. Our results showed that occupations and industries with higher mortality rates in men had the same trend as the results from 2010, and occupations and industries with higher mortality rates in women were almost the same as those in men. The analyses also indicated that managerial and professional workers in Japan had higher mortality as opposed to developed Western countries. In conclusion, this study suggests that occupations and industries still impact men and women's health in terms of mortality due to gastric cancer in Japan.

Occupational exposures and odds of gastric cancer: a StoP project consortium pooled analysis

BACKGROUND

Gastric cancer pathogenesis represents a complex interaction of host genetic determinants, microbial virulence factors and environmental exposures. Our primary aim was to determine the association between occupations/occupational exposures and odds of gastric cancer.

METHODS

We conducted a pooled-analysis of individual-level data harmonized from 11 studies in the Stomach cancer Pooling Project. Multivariable logistic regression was used to estimate the odds ratio (OR) of gastric cancer adjusted for relevant confounders.

RESULTS

A total of 5279 gastric cancer cases and 12 297 controls were analysed. There were higher odds of gastric cancer among labour-related occupations, including: agricultural and animal husbandry workers [odds ratio (OR) 1.33, 95% confidence interval (CI): 1.06-1.68]; miners, quarrymen, well-drillers and related workers (OR 1.70, 95% CI: 1.01-2.88); blacksmiths, toolmakers and machine-tool operators (OR 1.41, 95% CI: 1.05-1.89); bricklayers, carpenters and construction workers (OR 1.30, 95% CI: 1.06-1.60); and stationary engine and related equipment operators (OR 6.53, 95% CI: 1.41-30.19). The ORs for wood-dust exposure were 1.51 (95% CI: 1.01-2.26) for intestinal-type and 2.52 (95% CI: 1.46-4.33) for diffuse-type gastric cancer. Corresponding values for aromatic amine exposure were 1.83 (95% CI: 1.09-3.06) and 2.92 (95% CI: 1.36-6.26). Exposure to coal derivatives, pesticides/herbicides, chromium, radiation and magnetic fields were associated with higher odds of diffuse-type, but not intestinal-type gastric cancer.

CONCLUSIONS

Based on a large pooled analysis, we identified several occupations and related exposures that are associated with elevated odds of gastric cancer. These findings have potential implications for risk attenuation and could be used to direct investigations evaluating the impact of targeted gastric cancer prevention/early detection programmes based on occupation.

Gastric cancer: epidemiology, prevention, classification, and treatment

Gastric cancer is the second most common cause of cancer-related deaths in the world, the epidemiology of which has changed within last decades. A trend of steady decline in gastric cancer incidence rates is the effect of the increased standards of hygiene, conscious nutrition, and Helicobacter pylori eradication, which together constitute primary prevention. Avoidance of gastric cancer remains a priority. However, patients with higher risk should be screened for early detection and chemoprevention. Surgical resection enhanced by standardized lymphadenectomy remains the gold standard in gastric cancer therapy. This review briefly summarizes the most important aspects of gastric cancers, which include epidemiology, risk factors, classification, diagnosis, prevention, and treatment. The paper is mostly addressed to physicians who are interested in updating the state of art concerning gastric carcinoma from easily accessible and credible source.

Use of job-exposure matrices to estimate occupational exposure to pesticides: A review

The health effects of pesticides have been extensively studied in epidemiology, mainly in agricultural populations. However, pesticide exposure assessment remains a key methodological issue for epidemiological studies. Besides self-reported information, expert assessment or metrology, job-exposure matrices still appear to be an interesting tool. We reviewed all existing matrices assessing occupational exposure to pesticides in epidemiological studies and described the exposure parameters they included. We identified two types of matrices, (i) generic ones that are generally used in case-control studies and document broad categories of pesticides in a large range of jobs, and (ii) specific matrices, developed for use in agricultural cohorts, that generally provide exposure metrics at the active ingredient level. The various applications of these matrices in epidemiological studies have proven that they are valuable tools to assess pesticide exposure. Specific matrices are particularly promising for use in agricultural cohorts. However, results obtained with matrices have rarely been compared with those obtained with other tools. In addition, the external validity of the given estimates has not been adequately discussed. Yet, matrices would help in reducing misclassification and in quantifying cumulated exposures, to improve knowledge about the chronic health effects of pesticides.

Gastric cancer incidence in the Romagna Region of Italy: A spatial and temporal analysis

BACKGROUND

The worldwide decrease in gastric cancer incidence is due to a birth-cohort-dependent decrease in exposure to major risk factors.

METHODS

In an area of northern Italy with a historically strong internal geographical gradient in gastric cancer incidence, variations in rates by municipality and age group between 1987 and 2008 were evaluated. The study period was divided into three nonadjacent periods. End points included: age- and sex-standardised incidence rates; incidence rate ratio between age- and sex-standardised incidence rates; smoothed relative risks of gastric cancer incidence, and posterior probabilities of the relative risk being >1.

RESULTS

In 1987-1990, the estimate of posterior probabilities of relative risk being >1 showed a higher incidence in hilly/mountainous areas. Between 1987-1990 and 2005-2008, a uniform decrease of more than 50% was observed (incidence rate ratio: plain, 0.45 (95% confidence interval 0.40-0.51); hill, 0.44 (0.34-0.58); mountain, 0.48 (0.22-1.02)). The decrease in the mountainous area was weak in the middle time period, with an incidence rate ratio of 0.92 (0.46-1.84), and intensified afterwards. The decrease occurred earlier and was more pronounced among younger people. In 2005-2008, gastric cancer risk was uniform across ages and municipalities.

CONCLUSIONS

The observed changes in gastric cancer incidence is the epilogue of a birth-cohort-dependent decrease in exposure to major risk factors.

Current understanding of mdig/MINA in human cancers

Mineral dust-induced gene, mdig has recently been identified and is known to be overexpressed in a majority of human cancers and holds predictive power in the poor prognosis of the disease. Mdig is an environmentally expressed gene that is involved in cell proliferation, neoplastic transformation and immune regulation. With the advancement in deciphering the prognostic role of mdig in human cancers, our understanding on how mdig renders a normal cell to undergo malignant transformation is still very limited. This article reviews the current knowledge of the mdig gene in context to human neoplasias and its relation to the clinico-pathologic factors predicting the outcome of the disease in patients. It also emphasizes on the promising role of mdig that can serve as a potential candidate for biomarker discovery and as a therapeutic target in inflammation and cancers. Considering the recent advances in understanding the underlying mechanisms of tumor formation, more preclinical and clinical research is required to validate the potential of using mdig as a novel biological target of therapeutic and diagnostic value.

Physical and chemical insults induce inflammation and gastrointestinal cancers

Chronic inflammation associated with viral and bacterial infections of the gastrointestinal tract (GI) and liver renders these organs susceptible to tumour development. There is also a growing body of evidence demonstrating that chemical and physical insults promote GI cancers by inducing inflammation. For example, excessive alcohol consumption and tobacco smoking induces inflammation and gastrointestinal carcinogenesis. Likewise, drinking hot beverages and intentional or accidental exposure to toxic substances leads to inflammation and GI cancer formation. However, further work needs to be undertaken using animal models to separate the direct carcinogenic effects of physical and chemical insults from the indirect effects of these insults to promote tumor formation through tissue inflammation.

Incidence and mortality trends of gastric and colorectal cancers in Croatia, 1988-2008

AIM

To estimate the incidence and mortality trends of gastric and colorectal cancers in Croatia between 1988 and 2008.

METHODS

Incidence data for the period 1988-2008 were obtained from the Croatian National Cancer Registry. The number of deaths from gastric and colorectal cancers were obtained from the World Health Organization mortality database. Joinpoint regression analysis was used to describe changes in trends by sex.

RESULTS

Gastric cancer incidence rates declined steadily during the study period, with estimated annual percent change (EAPC) of -3.2% for men and -2.8% for women. Mortality rates in men decreased, with EAPC of -5.0% from 1988-1995 and -2.5% from 1995-2008. Mortality rates in women decreased, with EAPC of -3.2% throughout the study period. For colorectal cancer in men, joinpoint analysis revealed increasing trends of both incidence (EAPC 2.9%) and mortality (EAPC 2.1%). In women, the increase in incidence was not significant, but mortality rates in the last 15 years showed a significant increase (EAPC 1.1%).

CONCLUSION

The incidence and mortality trends of gastric cancer in Croatia are similar to other European countries, while the still increasing colorectal cancer mortality calls for more efficient prevention and treatment.

Gastric cancer mortality trends in Spain, 1976-2005, differences by autonomous region and sex

BACKGROUND

Gastric cancer is the second leading cause of oncologic death worldwide. One of the most noteworthy characteristics of this tumor's epidemiology is the marked decline reported in its incidence and mortality in almost every part of the globe in recent decades. This study sought to describe gastric cancer mortality time trends in Spain's regions for both sexes.

METHODS

Mortality data for the period 1976 through 2005 were obtained from the Spanish National Statistics Institute. Cases were identified using the International Classification of Diseases 9th and 10th revision (codes 151 and C16, respectively). Crude and standardized mortality rates were calculated by geographic area, sex, and five-year period. Joinpoint regression analyses were performed to ascertain whether changes in gastric cancer mortality trends had occurred, and to estimate the annual percent change by sex and geographic area.

RESULTS

Gastric cancer mortality decreased across the study period, with the downward trend being most pronounced in women and in certain regions situated in the interior and north of mainland Spain. Across the study period, there was an overall decrease of 2.90% per annum among men and 3.65% per annum among women. Generally, regions in which the rate of decline was sharpest were those that had initially registered the highest rates. However, the rate of decline was not constant throughout the study period: joinpoint analysis detected a shift in trend for both sexes in the early 1980s.

CONCLUSION

Gastric cancer mortality displayed in both sexes a downward trend during the study period, both nationally and regionally. The different trend in rates in the respective geographic areas translated as greater regional homogeneity in gastric cancer mortality by the end of the study period. In contrast, rates in women fell more than did those in men. The increasing differences between the sexes could indicate that some risk factors may be modifying the sex-specific pattern of this tumor.

Hyperglycaemia, hypercholesterolaemia and the risk for developing gastric dysplasia

BACKGROUND/GOALS

Gastric dysplasia is believed to be the penultimate stage of gastric carcinogenesis. Few studies have evaluated whether there is a relationship between such risk factors and gastric dysplasia. This case-control study was conducted to investigate the associations between obesity, serum glucose, lipids and gastric dysplasia.

STUDY

Endoscopic findings and pathology specimens were reviewed from 1 July 1997 to 31 December 2006 in the Health Promotion Center. One hundred thirty patients have the dysplasia in the stomach during screening endoscopy. The same number of controls was evaluated and matched to the gastric dysplasia group for age and gender.

RESULT

The univariate analysis showed that the dysplasia risk was slightly increased among persons with a higher low-density lipoprotein, lower high-density lipoprotein, impaired fasting glucose and higher total cholesterol. However, a higher body mass index and higher triglyceride level were not associated with the diagnosis of gastric dysplasia. In the multivariate-adjusted model, a higher low-density lipoprotein cholesterol and glucose were strongly associated with an increased risk of dysplasia compared to the controls. However, the body mass index, triglyceride and total cholesterol were not associated with the risk for dysplasia.

CONCLUSION

Hyperglycaemia and low-density lipoprotein cholesterol appear to be associated with the risk for gastric dysplasia. Further epidemiologic studies including a large cohort of patients with gastric dysplasia and adenocarcinoma are needed to clarify the association of low-density lipoprotein cholesterol, serum glucose and gastric carcinogenesis.

Socio-economic and occupational risk factors for gastric cancer: a cohort study in Sweden

The effects of socio-economic/occupational factors on gastric cancer at various subsites (including corpus, cardia and unspecified cancers) are not well known. To investigate this issue, we carried out a follow-up study on the economically active Swedish population, based on the Swedish Family-Cancer Database. We calculated standardized incidence ratios and 95% confidence intervals for different occupational groups, adjusted for age, period, region and socio-economic status. The reference group was all the economically active population. Manual workers and farmers were at an increased risk of stomach cancer. An increased risk of corpus cancer was observed for male miners and quarry workers, fishermen, construction workers, packers, loaders and warehouse workers, clerical workers and female assistant nurses and postal workers. For cardia cancer, significantly increased standardized incidence ratios were observed for gardeners, transport workers, bricklayers and chemical process workers among men. Only male miner and quarry workers showed significantly increased risk of unspecified cancer. In conclusion, the present study indicates that socio-economic groups differ in risk by almost a factor of two for corpus and unspecified cancers, and less for cardia cancers. Cement and mineral dusts appear as major occupational risk factors.

Airborne exposures and risk of gastric cancer: A prospective cohort study

There is an unexplained male predominance among patients with gastric cancer, and many carcinogens are found in male-dominated dusty occupations. However, the relation between occupational exposures and risk of gastric cancer remains unclear. To investigate whether airborne occupational exposures might influence the risk of noncardia gastric cancer, we used a large, prospective cohort study of male Swedish construction workers. These workers were, during the period 1971-1993, regularly invited to health examinations by a nationwide occupational health service organization. Data on job titles and other variables were collected through self-administered questionnaires and forms completed by the health organization's staff. Industrial hygienists assessed 12 specific airborne occupational exposures for 200 job titles. Gastric cancer, death or emigration occurring during follow-up in 1971-2002 were identified by linkage to the Swedish registers of Cancer, Causes of Death and Total Population, respectively. Incidence rate ratios (IRR) and 95% confidence intervals (CI), adjusted for attained age, tobacco smoking, calendar period and body mass, were derived from Cox regression. Among 256,357 cohort members, contributing 5,378,012 person-years at risk, 948 noncardia gastric cancers were identified. Increased risk of this tumor was found among workers exposed to cement dust (IRR 1.5 [95% CI 1.1-2.1]), quartz dust (IRR 1.3 [95% CI 1.0-1.7]) and diesel exhaust (IRR 1.4 [95% CI 1.1-1.9]). Dose-response relations were observed for these exposures. No consistent positive associations were found regarding exposure to asbestos, asphalt fumes, concrete dust, epoxy resins, isocyanates, metal fumes, mineral fibers, organic solvents or wood dust. In conclusion, this study provides some support to the hypothesis that specific airborne exposures increase the risk of noncardia gastric cancer.

Cancer mortality in an area of Campania (Italy) characterized by multiple toxic dumping sites

Several recent studies have documented that a widespread practice of dumping toxic wastes has taken place for many years in the Provinces of Naples and Caserta. Extensive programs of environmental monitoring are currently ongoing in the area. In this frame, the Department of Civil Defence of the Italian Government has appointed an ad hoc study group in order to assess the health status of the population resident in the area of interest. The first investigation performed by the study group has been a geographic study on cancer mortality and occurrence of malformations in 196 municipalities constituting the two Provinces. The study detected an area located in the southeastern part of the Province of Caserta and in the northwestern part of the Province of Naples, where cancer mortality and congenital malformations show significantly increased rates with respect to expected figures derived from the regional population. The area highlighted by the study is, in general terms, overlapping with the area where most illegal dumping of toxic wastes took place. It is now recommended that mortality studies be extended to take into account other health outcomes, to search for correlations with environmental exposures, and consider possible confounding factors.

Gastric cancer: global pattern of the disease and an overview of environmental risk factors

This first part of this chapter looks at the worldwide burden of gastric cancer at the beginning of the 21st century and summarises available population-based routine data that describes the variation in incidence of the disease in relation to age, sex, geography and time period. Consideration is also given to the differences in the descriptive epidemiology of gastric cancer arising in the proximal cardia region of the stomach. In the second part of the chapter, a brief review of the main identified environmental risk factors is conducted drawing, where available, on published systematic literature overviews and meta-analyses. Evidence relating the aetiology of gastric cancer to Helicobacter pylori infection, dietary factors, smoking, occupation, physical activity and anthropometry is presented.

Cancer mortality among men occupationally exposed to dichlorodiphenyltrichloroethane

Several studies have evaluated cancer risk associated with occupational and environmental exposure to dichlorodiphenyltrichloroethane (DDT). Results are mixed. To further inquire into human carcinogenicity of DDT, we conducted a mortality follow-up study of 4,552 male workers, exposed to DDT during antimalarial operations in Sardinia, Italy, conducted in 1946 to 1950. Detailed information on DDT use during the operations provided the opportunity to develop individual estimates of average and cumulative exposure. Mortality of the cohort was first compared with that of the Sardinian population. Overall mortality in the cohort was about as expected, but there was a deficit for death from cardiovascular disease and a slight excess for nonmalignant respiratory diseases and lymphatic cancer among the unexposed subcohort. For internal comparisons, we used Poisson regression analysis to calculate relative risks of selected malignant and nonmalignant diseases with the unexposed subcohort as the reference. Cancer mortality was decreased among DDT-exposed workers, mainly due to a reduction in lung cancer deaths. Birth outside from the study area was a strong predictor of mortality from leukemia. Mortality from stomach cancer increased up to 2-fold in the highest quartile of cumulative exposure (relative risk, 2.0; 95% confidence interval, 0.9-4.4), but no exposure-response trend was observed. Risks of liver cancer, pancreatic cancer, and leukemia were not elevated among DDT-exposed workers. No effect of latency on risk estimates was observed over the 45 years of follow-up and within selected time windows. Adjusting risks by possible exposure to chlordane in the second part of the antimalarial operations did not change the results. In conclusion, we found little evidence for a link between occupational exposure to DDT and mortality from any of the cancers previously suggested to be associated.

Relative and absolute cancer mortality of women in agriculture in northern Italy

Most studies of cancer risk related to agricultural exposures have focused on male operators. Cancer mortality in a cohort of 38 962 women engaged in agriculture (Province of Forlì, 1969-1993) was compared with that of the rest of the female residents using the ratio of age-standardized (Europe) mortality rates (ASR) with 95% confidence interval (CI). Moreover, mortality time trends in both subsets of the population were evaluated. The cohort yielded 798 439 person-years with 2397 cancer deaths. Total ASR ratio was 0.86 (95% CI 0.80-0.92). Only gastric cancer was associated with a significant but declining excess mortality (ASR ratio 1.26; 95% CI 1.11-1.43). Total ASR ratio decreased from 1.07 (95% CI 0.95-1.20) in 1969-1976 to 0.74 (95% CI 0.66-0.82) in 1985-1993. This resulted from a downward mortality trend restricted to the cohort. In particular, mortality from cancers of the oesophagus, stomach and colon/rectum decreased more steeply in the cohort. Mortality from liver cancer decreased only in the cohort. Mortality from cancers of the pancreas, lung, breast, bladder and skin melanoma remained stable in the cohort whilst increasing in the rest of the population. In conclusion, risk excesses previously reported were not confirmed. Agricultural workers qualified as a subset of the female population with atypical, favourable epidemiologic characteristics.

Occupation and risk of stomach cancer in Poland

BACKGROUND

In spite of the dramatic decline in the incidence of stomach cancer in the twentieth century, Poland has one of the highest rates in the world.

AIMS

To evaluate the risk of stomach cancer by grouped occupations and industries, as well as by some specific occupational exposures.

METHODS

Cases (n = 443) were newly diagnosed with stomach adenocarcinomas between 1994 and 1996. Controls (n = 479) were randomly selected from the general population in Warsaw.

RESULTS

Only a few occupations and industries were associated with significantly increased risks of stomach cancer. The most suggestive finding was for work in the leather goods industry. Risk was also significantly increased among men working in fabricated metal production and among women ever employed as managers and governmental officials. Men ever employed as teaching professionals and women employed as technical and science professionals had significantly decreased risks of stomach cancer. Among men, a significant positive trend in risk with duration of employment was observed for work in the leather industry and special trade construction. No significantly increased risks were observed for specific exposures assessed by a job-exposure matrix or by self-reports. However among men there were non-significantly increased risks with 10 or more years exposure to asbestos, metal dust, and nitrosamines assessed by a job-exposure matrix.

CONCLUSIONS

Employment in the leather goods industry, special trade construction, and metal fabrication was associated with an increased risk of stomach cancer among men. However, there were only weak associations with specific exposures. Occupational exposures do not contribute substantially to the high rates of stomach cancer in Poland.

Cancer mortality in a cohort of male agricultural workers from northern Italy

Cancer mortality in a cohort of 36,579 Italian male agricultural workers (Province of Forlì, 1969-1993) was compared with that of the rest of male population using the ratio of age-standardized (Europe) mortality rates (ASR) with the 95% confidence interval (CI). The cohort yielded 707,496.3 person-years with 3684 cancer deaths. Total ASR ratio was 0.85 (95% CI = 0.81-0.90). A significant excess mortality was observed only for gastric cancer (1.25; 1.13-1.39). Reduction in total cancer mortality was restricted to farm owners (0.83; 0.79-0.88), whereas excess gastric cancer mortality involved both farm owners (1.23; 1.11-1.37) and farm workers (1.32; 1.10-1.58). ASR ratio for gastric cancer decreased from 1.58 (1.34-1.86) in 1969-1976 to 0.97 (0.80-1.19) in 1985-1993. In conclusion, the only positive finding in this cohort of male agricultural workers was a generalized but declining excess mortality from gastric cancer.

Occupation and gastric cancer

Gastric cancer is a cause of significant morbidity and mortality. There are several risk factors, with occupation emerging as one of these. There is considerable evidence that occupations in coal and tin mining, metal processing, particularly steel and iron, and rubber manufacturing industries lead to an increased risk of gastric cancer. Other "dusty" occupations-for example, wood processing, or work in high temperature environments have also been implicated but the evidence is not strong. The mechanism of pathogenesis of gastric cancer is unclear and the identification of causative agents can be difficult. Dust is thought to be a contributor to the pathological process, but well known carcinogens such as N-nitroso compounds have been detected in some environments. Further research on responsible agents is necessary and screening for detection of precursor gastric cancer lesions at the workplace merits consideration.

Gastric cancer epidemiology and risk factors

We performed a detailed analysis of the epidemiology of gastric carcinoma, based upon a review of the literature in English. The analysis reveals many puzzling features. There has been a steady fall in the incidence of gastric carcinoma in most societies studied, but a more recent steady rise in the incidence of adenocarcinoma of the cardia and lower esophagus, largely confined to White males. Although the evidence for a major role for Helicobacter pylori (H. pylori) in the etiology of gastric corpus cancer is compelling; in Western society, it probably accounts for fewer than half the cases. The relative roles of dietary constituents such as salt and nitrites and the phenotyping of H. pylori in causation and the beneficial effects of a high fruit and vegetable diet and an affluent lifestyle, for all of which there is some evidence, are yet to be quantified.

Stomach cancer and occupation in Sweden: 1971-89

OBJECTIVES

To examine the relation between gastric cancer and occupation among men and women gainfully employed in 1970 in Sweden for the period 1971-89 and, more specifically, to evaluate whether any excess of incidence of gastric cancer had also occurred among the subcohort of people reporting the same occupation in 1960 and 1970.

METHODS

In both sexes and cohorts, relative risks adjusted for age, period of diagnosis, and geographical risk area were computed for occupational codes specified at one, two, or three level (occupational sector, occupational group, and occupation, respectively). Relative risks were calculated with all other occupations as reference and then, to take socioeconomic status into account, solely other occupations within the same occupational sector were used.

RESULTS

Among men, occupations with increased risk included miners and quarrymen, construction and metal processing workers, supporting the possible causative role of dusty environments in stomach cancer. In men, the results also provide support for increased risks among electrical and mechanical engineers, fishermen, petrol station workers, motor vehicle drivers, butchers and meat preparers, dockers, freight handlers, launderers and dry cleaners. Furthermore, it is worth noting interesting results for women, whose occupational risks have been studied less. Excess risks were found for practical nurses, cashiers, bank employees, engineering and electronic industry workers, food industry, housekeeping and cleaning workers. Due to the many occupations studied, several significant associations may be expected by chance.

CONCLUSIONS

The study is explorative but provides support for the relations suggested previously between occupational exposure to dusty environments and stomach cancer, together with some new high risk occupations which should be further studied.

Review article: would eradication of Helicobacter pylori infection reduce the risk of gastric cancer?

This article reviews the data on the epidemiology of gastric cancer, to determine if treatment of an asymptomatic individual can be justified. It reviews retrospective and prospective case-control studies of gastric cancer in Italy and other countries. Mucosa-associated lymphoid tissue lymphoma is associated with Helicobacter pylori infection. The risk of noncardia gastric cancer is higher (4-fold or greater) in those with H. pylori infection. Although no studies have shown prevention following treatment, eradication of asymptomatic H. pylori infection in an individual in the age group 40 or lower may be expected to reduce the risk of gastric cancer.

Lifestyle habits and gastric cancer in a hospital-based case-control study in Taiwan

OBJECTIVES

The aim of this study was to evaluate the effect of lifestyle habits on the risk of primary gastric cancer.

METHODS

A hospital-based case-control study of matched pairs was conducted in Kaohsiung, Taiwan, from 1992 to 1996. The study included 649 subjects (152 cases and 497 controls). All subjects were personally interviewed face-to-face by a trained interviewer using a structured questionnaire to collect data about lifestyle. An average of approximately three controls were matched to each case based on age (+/-3 yr), sex, and time of hospitalization (+/-2 wk). Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to evaluate results, and a multivariate analysis of the data was performed using a conditional logistic regression model.

RESULTS

A significantly elevated risk of contracting gastric cancer was observed in cigarette smokers (OR: 2.7, 95% CI: 1.5-4.3), but not in drinkers of alcoholic beverages (OR: 1.5, 95% CI: 0.9-3.2). A synergistically augmented relationship (multiplication effect) was found between smoking and drinking alcohol for controlling the major confounders. The combined adjusted ORs for all subjects with gastric cancer were 3.0 (95% CI: 1.4-7.1) for current smokers and 1.7 (95% CI: 1.2-4.4) for ex-smokers. Furthermore, a statistically significant positive dose-response trend in gastric cancer was demonstrated based on the age at which smoking was initiated, the duration of the habit, the number of cigarettes smoked per day, and the degree of smoke inhalation. We did not find any association between the other risk factors and gastric carcinogenesis.

CONCLUSIONS

Our findings provide further evidence that in Taiwan, cigarette smoking may play the most harmful role in the initial development of gastric cancer, and that drinking alcohol may promote the process.

Risk of stomach cancer associated with 12 workplace hazards: analysis of death certificates from 24 states of the United States with the aid of job exposure matrices

OBJECTIVE

To investigate the risk of gastric cancer associated with 12 workplace exposures suspected or discussed as aetiological agents in previous reports.

METHODS

A case-control study was conducted based on the death certificates of several million deaths in 24 states of the United States in 1984-96. Overall, the data base included 41,957 deaths from stomach cancer among subjects aged > or = 25 years. These were 20,878 white men, 14,125 white women, 4215 African American men, and 2739 African American women. Two controls for each case were selected from among subjects who died from non-malignant diseases, frequency matched to cases by geographic region, race, sex and 5 year age group. Each three digit occupation and industry code listed in the 1980 United States census was classified for probability and intensity of exposure to asbestos, inorganic dust, metals, lead, polycyclic aromatic hydrocarbons (PAHs), nitrogen oxides, nitrosamines, sulphuric acid, fertilisers, herbicides, other pesticides (including insecticides and fungicides), and wood dust. These job exposure matrices were subsequently applied to the occupation-industry combinations in the death certificates of study subjects, separately by sex and race.

RESULTS

Risk of stomach cancer showed a modest association with occupational exposure to inorganic dust (odds ratio (OR) = 1.06; 95% confidence interval (95% CI) 1.03 to 1.11) with significant increasing trends by probability and intensity of exposure overall and by cross classification of the two exposure matrices. Workplace exposure to nitrosamines also showed a modest association (OR = 1.06; 95% CI 1.01 to 1.11), but the excess risk was even smaller after adjusting for inorganic dust exposure. Risk of gastric cancer was not associated with any of the other workplace exposures considered in this study.

CONCLUSIONS

Non-differential misclassification of exposure may have caused negative findings in this study, and inorganic dust may be a partial surrogate for exposure to other unknown risk factors. Alternatively, our results suggest that occupational factors contribute little to the aetiology of gastric cancer. Inorganic dust might act through non-specific mechanisms, similar to those proposed for salt, aspirin, and heat by other authors.

Cancer risk in the rubber industry: a review of the recent epidemiological evidence

OBJECTIVES

To examine the recent epidemiological evidence on cancer risk among workers in the rubber industry.

METHODS

Epidemiological studies published after the last detailed review by the International Agency for Research on Cancer (IARC) in 1982 were reviewed. 12 cohort studies in nine countries that examined distinct populations of workers in the rubber industry, seven industry based nested case-control studies, 48 community based case-control studies in 16 countries, and 23 studies based on administrative data that reported risks for employment in the rubber industry were identified.

RESULTS

Excess risks of bladder cancer, lung cancer, and leukaemia were found in most studies, with risks above 1.5 in about half of the studies. A moderate excess risk for laryngeal cancer was consistent across studies. Excess risks were found in a few studies for cancers of the oesophagus, stomach, colon, liver, pancreas, skin, prostate, kidney, brain, and thyroid, and for malignant lymphoma and multiple myeloma, but overall results were not consistent for these neoplasms.

CONCLUSIONS

Magnitude of the observed risks varied considerably between studies, but overall the findings indicate the presence of a widespread moderate increased cancer risk among rubber workers. The most consistent results were for bladder, laryngeal, and lung cancer and for leukaemia. Excess risks were also found for other neoplasms but an evaluation of the consistency of the findings is difficult because of the possible selective reporting of results. Recent studies do not provide information associating specific exposures with cancer risk. The preventive measures taken in the rubber industry in recent years may decrease risks, but this has not been documented yet in epidemiological studies.