Risk factors for oesophageal cancer in northeast China

Alcohol drinking and esophageal squamous cell carcinoma with focus on light-drinkers and never-smokers: a systematic review and meta-analysis

Quantification of the association between alcohol drinking and risk of esophageal squamous cell carcinoma (ESCC) is an open issue, particularly among light alcohol drinkers, never-smokers, and Asian populations, in which some high-risk polymorphisms in alcohol metabolizing genes are more prevalent. To address these issues, we conducted a systematic review and meta-analysis using 40 case-control and 13 cohort studies that reported on the risk associated with alcohol drinking for at least three levels of consumption. In studies adjusted for age, sex, and tobacco smoking, the relative risk (RR) and 95% confidence interval (CI) for the association between light alcohol drinking (≤ 12.5 g/d) and risk of ESCC was 1.38 (1.14-1.67). The association was slightly stronger in Asian countries than in other populations. The adjusted RRs (95% CIs) were 2.62 (2.07-3.31) for moderate drinking (>12.5-<50 g/d) and 5.54 (3.92-7.28) for high alcohol intake (≥50 g/d); the RRs were slightly higher in non-Asian populations. In prospective studies, the RR (95% CI) was 1.35 (0.92-1.98) for light, 2.15 (1.55-2.98) for moderate, and 3.35 (2.06-5.46) for high alcohol intakes; light drinking showed an association with ESCC in Asia (five studies) but not in other regions (three studies). Among never-smokers (nine studies), the RR (95% CI) was 0.74 (0.47-1.16) for light, 1.54 (1.09-2.17) for moderate, and 3.09 (1.75-5.46) for high intakes. This meta-analysis further corroborates the association of moderate and high alcohol intake with risk of ESCC and provides risk estimates based on multiple prospective studies. Light alcohol intake appears to be associated to ESCC mainly in studies in Asia, which suggests a possible role of genetic susceptibility factors.

Genetic polymorphism of p53, but not GSTP1, is association with susceptibility to esophageal cancer risk - a meta-analysis

A number of studies have evaluated two functional polymorphisms on p53 Arg72Pro and GSTP1 Ile105Val, in relation to esophageal cancer susceptibility. However, the results remain conflicting rather than conclusive. This meta-analysis on 2919 cases and 4074 controls for p53 Arg72Pro and 1885 cases and 2194 controls for GSTP1 Ile105Val from 13 published case-control studies showed that no significant general main effects for GSTP1 Ile105Val on esophageal cancer risk. However, we found that the p53 Arg72Pro was associated with an increased risk of esophageal cancer ((Pro/Arg +Pro/Pro) versus Arg/Arg: OR=1.20, 95%CI=1.06-1.36) without any between-study heterogeneity. In the stratified analysis by ethnicity, we found that the increased esophageal cancer risk associated with p53 Arg72Pro polymorphism was more evident in Asian group ((Pro/Arg +Pro/Pro) versus Arg/Arg: OR=1.35, 95%CI=1.14-1.60, P=0.09 for heterogeneity test), although we still failed to find any significant association between GSTP1 Ile105Val polymorphism and esophageal cancer risk in different ethnicity. These results suggest that p53 Arg72Pro polymorphism, but not GSTP1 Ile105Val, may contribute to esophageal cancer development, especially in Asian. Additional well-designed large studies were required for the validation of this association.

Is temperature an effect modifier of the association between green tea intake and gastric cancer risk?

We considered the relationship between green tea and gastric cancer risk in Harbin, Heilongjiang province, Northeast China, an area with high baseline risk of stomach cancer. We used data from a case-control study conducted from 1987 to 1989 among 266 incident cases of stomach cancer and 533 controls admitted to the same hospitals as cases, with non-neoplastic and non-gastric diseases. No association emerged when tea consumption alone was considered: the odds ratio (OR) for green tea consumption was 0.87 (95% CI: 0.60-1.25) for green tea intake > or = 750 g/year versus no intake and 0.99 (95% CI: 0.97-1.02) for an increment of 500 g of tea per year. When tea consumption was classified according to the temperature, however, the OR was 0.19 (95% CI: 0.07-0.49) for lukewarm tea intake > or = 750 g/year and 1.27 (95% CI: 0.85-1.90) for hot tea intake (P value for interaction <0.001) as compared with non-drinkers. The corresponding ORs for an increment of 500 g of tea per year were 0.61 (95% CI: 0.45-0.82) and 1.03 (95% CI: 0.99-1.07) for lukewarm and hot tea, respectively (P value for interaction <0.001). We found an inverse relationship between green tea drinking and gastric cancer risk limited to the intake of lukewarm tea.

TP53 mutation profile of esophageal squamous cell carcinomas of patients from Southeastern Brazil

Esophageal cancer (EC) is among the 10 most common and fatal malignacies in the world, presenting a marked geographic variation in incidence rates between and within different countries. The TP53 tumor suppressor gene is highly mutated in esophageal tumors and its mutation pattern can offer clues to the etiopathology of the tumor. As Brazil presents one of the highest incidence areas in the West, a deeper knowledge of the molecular mechanisms related to EC development in the Brazilian population is needed. We analyzed the mutation profile of 110 esophageal squamous cell carcinomas (ESCC) of patients from Southeastern Brazil (Rio de Janeiro and São Paulo) and collected data regarding alcohol intake and tobacco smoking. We detected 41 mutations in tumor samples from 38 patients. There was no association between mutation frequency and tobacco smoking or alcohol drinking. The most frequently mutated codons were 179, 214, 220 and 248. Codons 179, 220 and 248 are hot-spots for ESCC, but codon 214 presents only 0.7% of the mutations registered in the IARC database. The mutation profile revealed a high percentage of mutations at A:T base pairs (34.1%) followed by deletions (17.1%). We concluded that the mutation profile detected in this study is different from that of patients from Southern Brazil but very similar to that previously seen in French patients, being characterized by a high frequency of mutations at A:T base pairs, which may be associated with acetaldehyde, the metabolic product of ethanol.

Pickled vegetables and the risk of oesophageal cancer: a meta-analysis

BACKGROUND

Ecological and experimental studies have suggested a relationship between Asian pickled vegetable consumption and oesophageal squamous cell carcinoma (OSCC), but the results of epidemiological studies investigating the association have been inconsistent. We conducted a meta-analysis of observational studies of this association to evaluate the existing evidence.

METHODS

We searched the PubMed, ISI-Web of Science, J-EAST, IndMed, Vip Chinese Periodical, and China National Knowledge Infrastructure databases for all studies published in English or Chinese languages. Pooled results for all studies combined and for several study subgroups were computed.

RESULTS

A total of 34 studies were included in this analysis. The overall random effects odds ratio (OR) and 95% confidence interval (CI) for pickled vegetable consumption was 2.08 (1.66-2.60), but the results were heterogeneous across studies. After excluding the three most influential studies, the respective numbers were 2.32 (1.92-2.81). Similar to the overall association, the majority of subgroup analyses showed a statistically significant association between consuming pickled vegetables and OSCC risk. There were only three prospective studies.

CONCLUSION

Our results suggest a potential two-fold increased risk of oesophageal cancer associated with the intake of pickled vegetables. However, because the majority of data was from retrospective studies and there was a high heterogeneity in the results, further well-designed prospective studies are warranted.

High-temperature beverages and foods and esophageal cancer risk--a systematic review

Coffee, tea and maté may cause esophageal cancer (EC) by causing thermal injury to the esophageal mucosa. If so, the risk of EC attributable to thermal injury could be large in populations in which these beverages are commonly consumed. In addition, these drinks may cause or prevent EC via their chemical constituents. Therefore, a large number of epidemiologic studies have investigated the association of an indicator of amount or temperature of use of these drinks or other hot foods and beverages with risk of EC. We conducted a systematic review of these studies and report the results for amount and temperature of use separately. By searching PubMed and the ISI, we found 59 eligible studies. For coffee and tea, there was little evidence for an association between amount of use and EC risk; however, the majority of studies showed an increased risk of EC associated with higher drinking temperature which was statistically significant in most of them. For maté drinking, the number of studies was limited, but they consistently showed that EC risk increased with both amount consumed and temperature, and these 2 were independent risk factors. For other hot foods and drinks, over half of the studies showed statistically significant increased risks of EC associated with higher temperature of intake. Overall, the available results strongly suggest that high-temperature beverage drinking increases the risk of EC. Future studies will require standardized strategies that allow for combining data and results should be reported by histological subtypes of EC.

N-nitroso compounds: assessing agreement between food frequency questionnaires and 7-day food records

BACKGROUND

N-nitroso compounds are recognized as important dietary carcinogens. Accurate assessment of N-nitroso intake is fundamental to advancing research regarding its role with cancer. Previous studies have not used a quantitative database to estimate the intake of these compounds in a US population.

OBJECTIVE

To address this gap, a database of N-nitroso values was developed in conjunction with an existing food frequency questionnaire (FFQ). In this article we report on the relative validity of the FFQ instrument modified to estimate intake of N-nitroso compounds.

DESIGN

Intake estimates of 23 N-nitroso compounds from the FFQ were compared with those from 7-day food records in a cross-sectional study conducted from January 2005 through June 2006.

SUBJECTS

A sample of 98 healthy adult subjects (aged 50.42+/-12.84 years) completed an FFQ and then recorded foods and beverages consumed on 7-day food records.

RESULTS

Crude and energy-adjusted N-nitroso compounds intakes were significantly higher in the FFQ than the 7-day food records (P<0.001). Spearman correlations for crude and energy-adjusted N-nitroso intakes ranged from 0.004 to 0.48. By tertiles of N-nitiroso compounds, there was moderate agreement (kappa>0.30) for five compounds. Higher estimates of N-nitroso compounds by FFQ was explained by a greater proportion of subjects who reported eating foods high in N-nitroso compounds on FFQ than reported on 7-day food records.

CONCLUSION

The modified FFQ with N-nitroso values is a useful tool for assessing N-nitroso intakes relative to a group, and captures all food items with N-nitroso compounds, including those foods with high concentrations and eaten sporadically.

Environmental causes of esophageal cancer

This article reviews the environmental risk factors and predisposing conditions for the two main histologic types of esophageal cancer. Tobacco smoking, excessive alcohol consumption, drinking maté, low intake of fresh fruits and vegetables, achalasia, and low socioeconomic status increase the risk of esophageal squamous cell carcinoma. Results of investigations on other potential risk factors, including opium consumption, intake of hot drinks, eating pickled vegetables, poor oral health, and exposure to human papillomavirus, polycyclic aromatic hydrocarbons, N-nitroso compounds, acetaldehyde, and fumonisins are discussed. Gastroesophageal reflux, obesity, tobacco smoking, hiatal hernia, achalasia, and, probably, absence of H pylori in the stomach increase the risk of esophageal adenocarcinoma. Results of studies investigating other factors are also discussed.

Garlic intake and cancer risk: an analysis using the Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims

BACKGROUND

Numerous animal and in vitro studies provided evidence for a relation between garlic intake and cancer risk reduction. Several studies also reported an inverse association in humans. However, no claims have been made about garlic intake and cancer risk reduction with respect to food labeling.

OBJECTIVE

The objective of this study was to evaluate the scientific evidence for garlic intake with respect to the risk of different types of cancer using the US Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims.

DESIGN

Literature searches were conducted by using the Medline and EMBASE databases for the period 1955-2007 with search terms Allium sativum, vegetables, diet, and nutrition in combination with cancer, neoplasm, and individual cancers. The search was limited to human studies published in English and Korean.

RESULTS

With the use of the US Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims, 19 human studies were identified and reviewed to evaluate the strength of the evidence that supports a relation between garlic intake and reduced risk of different cancers with respect to food labeling.

CONCLUSIONS

There was no credible evidence to support a relation between garlic intake and a reduced risk of gastric, breast, lung, or endometrial cancer. Very limited evidence supported a relation between garlic consumption and reduced risk of colon, prostate, esophageal, larynx, oral, ovary, or renal cell cancers.

Fruit and vegetable consumption and squamous cell carcinoma of the esophagus in Japan: the JPHC study

Epidemiological studies have consistently demonstrated a decrease in the risk of esophageal squamous cell carcinoma (SCC) associated with higher fruit and vegetable intake, although the association has been examined predominantly in case-control studies. Here, we conducted a population-based prospective cohort study among middle-aged Japanese men. Lifestyle characteristics were investigated using a self-administered questionnaire, which included a validated food frequency questionnaire with 138 food and beverage items. We followed a total of 38,790 men aged 45-74 years. A Cox proportional hazards model was used to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) for esophageal SCC, with adjustment for potential confounders. During 297,651 person-years of follow-up, a total of 116 men were newly diagnosed with esophageal SCC. An increase in consumption of total fruit and vegetables by 100 grams per day (g/day) was associated with an 11% decrease in the incidence of esophageal SCC (95% CI: 1-21%). In particular, a higher intake of cruciferous vegetables was associated with a significant decrease in risk (HR per 100 g/day: 0.44; 95% CI: 0.23-0.82). Stratified analyses revealed that the beneficial effect of fruits and vegetables was not able to completely offset the harmful effect of tobacco and alcohol. Our findings provide further evidence for the protective role of fruits and vegetables in the development of esophageal SCC. To effectively reduce the burden of this disease, however, priority should be placed on smoking and drinking cessation. Finally, cruciferous vegetables deserve further investigation as foods possibly effective in the prevention of esophageal SCC.

Food group intake and risk of subtypes of esophageal and gastric cancer

Incidence rates for adenocarcinomas of the esophagus and gastric cardia have been increasing rapidly, while rates for non-cardia gastric adenocarcinoma and esophageal squamous cell carcinoma have declined. We examined food group intake as a risk factor for subtypes of esophageal and gastric cancers in a multicenter, population-based case-control study in Connecticut, New Jersey and western Washington state. Associations between food groups and risk were estimated using adjusted odds ratios (OR), based on increasing intake of one serving per day. Total vegetable intake was associated with decreased risk of esophageal adenocarcinoma (OR = 0.85, 95% CI = 0.75, 0.96). Conversely, total meat intake was associated with increased risk of esophageal adenocarcinoma (OR = 1.43, 95% CI = 1.11, 1.83), gastric cardia adenocarcinoma (OR = 1.37, 95% CI = 1.08, 1.73) and noncardia gastric adenocarcinoma (OR = 1.39, 95% CI = 1.12, 1.71), with red meat most strongly associated with esophageal adenocarcinoma risk (OR = 2.49, 95% CI = 1.39, 4.46). Poultry was most strongly associated with gastric cardia adenocarcinoma (OR = 1.89, 95% CI = 1.15, 3.11) and noncardia gastric adenocarcinoma (OR = 1.90, 95% CI = 1.19, 3.03). High-fat dairy was associated with increased risk of both esophageal and gastric cardia adenocarcinoma. Higher intake of meats, particularly red meats, and lower intake of vegetables were associated with an increased risk of esophageal adenocarcinoma, while higher intake of meats, particularly poultry, and high-fat dairy was associated with increased risk of gastric cardia adenocarcinoma.

Nutrient intake and risk of squamous cell carcinoma of the esophagus: a case-control study in Uruguay

In 1996-2004 a case-control study on nutrient intake, dietary constituents and risk of squamous cell carcinoma of the esophagus was conducted in Montevideo, Uruguay. In fact, Uruguay, and especially its northern provinces, which border Brazil, are high-risk areas. The study included 234 cases and 936 controls. The controls were hospitalized patients with non-neoplastic disease, which was not related to tobacco smoking and alcohol drinking, and without recent changes in their diets. Controls were frequency matched to cases on age (10-yr intervals), sex, and residence (Montevideo and other provinces). Dietary constituents were energy adjusted using the residuals method and then categorized in quartiles according to the distribution of the controls. The final model included linoleic acid, lycopene, alpha-carotene, beta-cryptoxanthin, vitamin A, monounsaturated fat, total carbohydrates, beta-carotene, and folate. The odds ratio (OR) for high intake of linoleic acid was 1.4 (95% confidence interval, CI = 1.2-1.6), whereas lycopene displayed a strong protective effect (OR = 0.7; 95% CI = 0.6-0.9). The possible role of these and other dietary constituents in esophageal carcinogenesis is discussed.

Esophageal cancer in Central and Eastern Europe: Tobacco and alcohol

Esophageal cancer mortality rates in Central and Eastern Europe have been increasing steadily and are expected to increase further in the future. To evaluate the role of risk factors for esophageal cancer in this population, a multicenter study was conducted, with investigation of tobacco and alcohol as one of the principal aims. We have included 192 squamous cell carcinoma (SCC) and 35 adenocarcinoma cases of the esophagus diagnosed at designated hospitals in 5 centers from Romania, Russia, the Czech Republic and Poland. Controls were frequency matched from patients in the same hospital as the cases (n=1,114). Our results showed that the risk of esophageal SCC may be increased by approximately 7-fold for current smokers (OR=7.41, 95% CI 3.98-13.79) and by 3-fold for ever alcohol drinkers (OR=2.86, 95% CI 1.06-7.74). Dose-response relations were evident for both the frequency and duration of tobacco and of alcohol on the risk of esophageal SCC. Risk estimates for tobacco smoking were highest for lower esophageal SCCs, while risk estimates for alcohol drinking were highest for upper esophageal SCCs; though differences were not statistically significant. For adenocarcinoma of the esophagus, our results suggested a more modest increase in risk because of tobacco smoking than that for SCC of the esophagus and no association with alcohol consumption, although our sample size was small. A synergistic interaction between tobacco and alcohol was observed for the risk of esophageal SCC, highlighting the importance of both factors for esophageal cancers in Central and Eastern Europe.

Time trends in socioeconomic differences in incidence rates of cancers of gastro-intestinal tract in Finland

BACKGROUND

The magnitude of socioeconomic differences in health varies between societies, and over time within a given society. We studied the association between social class and incidence of cancers of the gastro-intestinal tract over time in a large cohort in Finland.

METHODS

We studied social class variation among 45-69 year-old Finns during 1971-95 in incidence of cancers of the gastro-intestinal tract by means of a computerized record linkage of the Finnish Cancer Registry and the 1970 Population Census, which included social class data.

RESULTS

There were 2.3 million individuals in the cohort under follow-up, with 1622 cases of cancer of the esophagus, 8069 stomach (non-cardia), 1116 cardia, 408 small intestine, 6361 colon, 5274 rectum, 1616 liver, 1756 gallbladder, and 5084 pancreas during 1971-1995. Cancers of the esophagus, stomach, cardia, gallbladder and pancreas were most common among persons belonging to a low social class. Cancers of the small intestine in males only, colon in both genders, and rectum in females were most common in the higher social classes. Incidence of stomach cancer decreased and incidence of colon cancer increased over time in both genders in all social classes, and the large differences between social classes remained unchanged over time. Incidence rates of cardia cancer did not change substantially over time.

CONCLUSION

There is a large variation in incidence of cancer of the gastrointestinal tract by social class in Finland. Although much of the observed social class differences probably could be explained by known etiological factors such as diet, physical exercise, alcohol consumption, smoking and exogenous hormone use, part of the variation is apparently attributable to largely unknown factors.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Onion and garlic use and human cancer

BACKGROUND

Interest in the potential benefits of allium vegetables, in particular, onion (Allium cepa) and garlic (Allium sativum), has its origin in antiquity, but the details of these benefits are still open to discussion.

OBJECTIVE

We investigated the role of allium vegetables in the etiology of various neoplasms. Previous data are scanty and are based mainly on Chinese studies.

DESIGN

Using data from an integrated network of Italian and Swiss case-control studies, we analyzed the relation between frequency of onion and garlic use and cancer at several sites. We calculated odds ratios (ORs) by using multivariate logistic regression models that were adjusted for energy intake and other major covariates.

RESULTS

Consumption of onions varied between 0-14 and 0-22 portions/wk among cases and controls, respectively. The multivariate ORs for the highest category of onion and garlic intake were, respectively, 0.16 and 0.61 for cancer of the oral cavity and pharynx, 0.12 and 0.43 for esophageal cancer, 0.44 and 0.74 for colorectal cancer, 0.17 and 0.56 for laryngeal cancer, 0.75 and 0.90 for breast cancer, 0.27 and 0.78 for ovarian cancer, 0.29 and 0.81 for prostate cancer, and 0.62 and 0.69 for renal cell cancer.

CONCLUSIONS

This uniquely large data set from southern European populations shows an inverse association between the frequency of use of allium vegetables and the risk of several common cancers. Allium vegetables are a favorable correlate of cancer risk in Europe.

Nitrosamine and related food intake and gastric and oesophageal cancer risk: A systematic review of the epidemiological evidence

AIM: To study the association between nitrite and nitrosamine intake and gastric cancer (GC), between meat and processed meat intake, GC and oesophageal cancer (OC), and between preserved fish, vegetable and smoked food intake and GC.

METHODS: In this article we reviewed all the published cohort and case-control studies from 1985-2005, and analyzed the relationship between nitrosamine and nitrite intake and the most important related food intake (meat and processed meat, preserved vegetables and fish, smoked foods and beer drinking) and GC or OC risk. Sixty-one studies, 11 cohorts and 50 case-control studies were included.

RESULTS: Evidence from case-control studies supported an association between nitrite and nitrosamine intake with GC but evidence was insufficient in relation to OC. A high proportion of case-control studies found a positive association with meat intake for both tumours (11 of 16 studies on GC and 11 of 18 studies on OC). A relatively large number of case-control studies showed quite consistent results supporting a positive association between processed meat intake and GC and OC risk (10 of 14 studies on GC and 8 of 9 studies on OC). Almost all the case-control studies found a positive and significant association between preserved fish, vegetable and smoked food intake and GC. The evidence regarding OC was more limited. Overall the evidence from cohort studies was insufficient or more inconsistent than that from case-control studies.

CONCLUSION: The available evidence supports a positive association between nitrite and nitrosamine intake and GC, between meat and processed meat intake and GC and OC, and between preserved fish, vegetable and smoked food intake and GC, but is not conclusive.

Cancer chemoprevention with garlic and its constituents

Advance metastasized cancers are generally incurable; hence an effort to prolong the process of carcinogenesis through chemoprevention has emerged consistent with this notion. In recent years, a considerable attention has been placed to identify naturally occurring chemopreventive substances capable of inhibiting, retarding or reversing the process of carcinogenesis. A number of phenolic substances, particularly those present in dietary and medicinal plants, have been shown to possess substantial anticarcinogenic and antimutagenic activities. Epidemiological observations and laboratory studies, both in cell culture and animal models have indicated anticarcinogenic potential of garlic and its constituents, which has been traditionally used for varied human ailments around the world. Chemical analysis has indicated that protective effects of garlic appear to be related to the presence of organosulfur compounds mainly allyl derivatives. Several mechanisms have been presented to explain cancer chemopreventive effects of garlic-derived products. These include modulation in activity of several metabolizing enzymes that activate and detoxify carcinogens and inhibit DNA adduct formation, antioxidative and free radicals scavenging properties and regulation of cell proliferation, apoptosis and immune responses. Recent data show that garlic-derived products modulate cell-signaling pathways in a fashion that controls the unwanted proliferation of cells thereby imparting strong cancer chemopreventive as well as cancer therapeutic effects. This review discusses mechanistic basis of cancer chemopreventive effects of garlic-derived products, their implication in cancer management and ways and means to take these agents from bench to real life situations.

Association of smoking, alcohol drinking and dietary factors with esophageal cancer in high- and low-risk areas of Jiangsu Province, China

AIM: To study the main environmental and lifestyle factors that account for the regional differences in esophageal cancer (EC) risk in low- and high-risk areas of Jiangsu Province, China.

METHODS: Since 2003, a population-based case-control study has been conducted simultaneously in low-risk (Ganyu County) and high-risk (Dafeng County) areas of Jiangsu Province, China. Using identical protocols and pre-tested standardized questionnaire, following written informed consent, eligible subjects were inquired about their detail information on potential determinants of EC, including demographic information, socio-economic status, living conditions, disease history, family cancer history, smoking, alcohol drinking, dietary habits, frequency, amount of food intake, etc. Conditional logistic regression with maximum likelihood estimation was used to obtain Odds ratio (OR) and 95 % confidence interval (95% CI), after adjustment for potential confounders.

RESULTS: In the preliminary analysis of the ongoing study, we recruited 291 pairs of cases and controls in Dafeng and 240 pairs of cases and controls in Ganyu, respectively. In both low-risk and high-risk areas, EC was inversely associated with socio-economic status, such as level of education, past economic status and body mass index. However, this disease was more frequent among those who had a family history of cancer or encountered misfortune in the past 10 years. EC was also more frequent among smokers, alcohol drinkers and fast eaters. Furthermore, there was a geographic variation of the associations between smoking, alcohol drinking and EC risk despite the similar prevalence of these risk factors in both low-risk and high-risk areas. The dose-response relationship of smoking and smoking related variables, such as age of the first smoking, duration and amount were apparent only in high-risk areas. On the contrary, a dose-response relationship on the effect of alcohol drinking on EC was observed only in low-risk areas.

CONCLUSION: The environmental risk factors, together with genetic factors and gene-environmental interactions might be the main reason for this high-risk gradient in Jiangsu Province, China.

Environmental exposure and p53 mutations in esophageal cancer patients in areas of low and high incidence of esophageal cancer in China

Esophageal cancer is the 6th most common cancer in the world, and genetic factors (p53 mutations) in addition to the environmental factors (food, nutrition, smoking, drinking, etc.) are involved in its development. In this study, the association between the both factors, environmental risk factors for esophageal cancer and p53 mutations, in tumor tissues was investigated in 77 patients living in a high-incidence area and 50 patients living in a low-incidence area in Hebei Province, China. Among these patients, p53 mutations were observed in about 50%, without regional differences in the respective frequencies. G:C>A:T (G to A or C to T) transition mutations were the major type of mutations observed in patients in the high-incidence area (19 patients, 50%), whereas G:C>A:T transitions and insertions were observed with equal frequency (8 patients, 33.3%) in the low-incidence area. As for the association with environmental factors, p53 mutations occurred with higher frequency in patients with a daily intake of spicy foods and in those who used unboiled well water in the low-incidence area. Logistic regression analysis showed no association between food intakes and p53 mutations in high- and low-incidence areas. Thus, higher frequency of spicy food intake and use of unboiled well water may be risk factors of esophageal cancer via p53 mutations in China.

The role of P53 and MDM2 polymorphisms in the risk of esophageal squamous cell carcinoma

The tumor suppressor P53 pathway plays a crucial role in preventing carcinogenesis and genetic variations of this pathway may be associated with cancer susceptibility. We tested this hypothesis by examining the contribution of functional polymorphisms in P53 and MDM2 to risk of esophageal squamous cell carcinoma (ESCC). DNA from 758 ESCC patients and 1,420 controls were genotyped for P53 codon 72Arg>Pro and MDM2 309T>G polymorphisms. Odds ratios (OR) and 95% confidence intervals (CI) of ESCC were estimated by logistic regression. We observed an increased risk of ESCC associated with the P53 Pro/Pro (OR, 1.83; 95% CI, 1.43-2.35; P < 0.001) or MDM2 GG (OR, 1.49; 95% CI, 1.16-1.91; P = 0.002) genotype, compared with the P53 Arg/Arg or MDM2 TT genotype, respectively. Interaction between these P53 and MDM2 polymorphisms increased risk of ESCC in a multiplicative manner, with the OR being 3.10 (95% CI, 2.07-4.69) for subjects carrying both P53 Pro/Pro and MDM2 GG genotypes. Significant interactions were observed between these polymorphisms and smoking, with risk being the highest (OR, 5.29; 95% CI, 2.91-9.61) in smokers having both P53 Pro/Pro and MDM2 GG genotypes. The MDM2 GG genotype was also associated with risk of developing poorly differentiated and advanced ESCC compared with the GT or TT genotype (OR for high-grade and stages III-IV versus low-grade and stages I-II = 1.60; 95% CI, 1.00-2.64; P = 0.049). The P53 and MDM2 polymorphisms may be genetic determinants for the development of ESCC.

Comparative proteomic analysis of esophageal squamous cell carcinoma

Ranking as the fourth commonest cancer, esophageal squamous cell carcinoma (ESCC) represents one of the leading causes of cancer death in China. One of the main reasons for the low survival rate is that neoplasms in esophagus are not detected until they have invaded into surrounding tissues or spread throughout the body at advanced stages. A better understanding of the malignant mechanism and early diagnosis are important for fighting ESCC. In this study, we used proteomics to analyze ESCC tissues, aiming at defining the proteomic features implicated in the multistage progression of esophageal carcinogenesis. Proteins that exhibited significantly different expressions were identified by peptide mass fingerprinting and validated by Western blotting and reverse transcriptase-polymerase chain reaction. The protein changes were then correlated to the different grades of disease differentiation. Compared to those in adjacent normal epitheliums, the expression of 15 proteins including enolase, elongation factor Tu, isocitrate dehydrogenase, tubulin alpha-1 chain, tubulin beta-5 chain, actin (cytoplasmic 1), glyceraldehyde-3 phosphate dehydrogenase, tropomyosin isoform 4 (TPM4), prohibitin, peroxiredoxin 1 (PRX1), manganese-containing superoxide dismutase (MnSOD), neuronal protein, and transgelin was up-regulated; and the expression of five proteins including TPM1, squamous cell carcinoma antigen 1 (SCCA1), stratifin, peroxiredoxin 2 isoform a, and alpha B crystalline was down-regulated in cancer tissues with a statistical significance (p < 0.05). In addition, the differential expression of SCCA1, PRX1, MnSOD, TPM4, and prohibitin can be observed in precancerous lesions of ESCC. The expression of stratifin, prohibitin, and SCCA1 dropped with increasing dedifferentiation of ESCC. These data may suggest that these proteins contribute to the multistage process of carcinogenesis, tumor progression, and invasiveness of ESCC.

Association of methylenetetrahydrofolate reductase and thymidylate synthase promoter polymorphisms with genetic susceptibility to esophageal and cardia cancer in a Chinese high-risk population

Methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TS) are key enzymes in folate metabolism, which is essential for normal DNA methylation and synthesis. Common polymorphisms at the MTHFR nucleotides position 677 (C-T) and a 28-bp tandem repeat polymorphism (2R or 3R) in the TS promoter enhancer region (TSER) have been reported to be functional and are supposed to disturb the normal DNA methylation and synthesis leading to carcinogenesis. To investigate the association between these polymorphisms and the risk of esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA), we conducted a case-control study in the Anyang area where the incidence of ESCC is highest in northern China. Subjects consisted of 275 cases with ESCC, 129 cases with GCA and 310 sex- and age-matched cancer-free controls. The risk was evaluated in terms of age-sex adjusted odds ratios (ORs) and 95% confidence intervals (CIs) by unconditional logistic regression model. The ORs for the MTHFR677TT genotype compared with the MTHFR677CC/CT genotype were 1.62 (95% CI = 1.15-2.30) and 1.81 (1.17-2.81) for ESCC and GCA, respectively. The ORs for the TSER 2R/2R genotype relative to the other genotypes were 2.44 (0.89-6.73) and 3.94 (1.29-12.0) for SCC and GCA, respectively. These findings indicated that the folate metabolism plays an important role in carcinogenesis of ESCC and GCA and the common functionally polymorphisms MTHFRC677T and TSER have substantial influence in this metabolic pathway.

Palmoplantar keratoderma is associated with esophagus squamous cell cancer in Van region of Turkey: a case control study

BACKGROUND

Esophagus squamous cell cancer (ESCC) is the most common cancer in women with 20.2% and second in men with 10.7% relative frequency among all cancer cases diagnosed in Van Region in the east of Turkey. Ninety percent of all esophageal cancer cases are ESCC and 20-30% of them have family history of esophageal cancer. The most clear defined hereditary predisposition associated with ESCC is palmoplantar keratoderma (PPK). To examine the relationship between ESCC and PPK, we have carried out this case control study.

METHODS

The case group consisted of 48 subjects who had new diagnosis of ESCC and did not receive any chemo or radiotherapy. The control group consisted of 96 healthy individuals who were visitors of their relatives in the hospital. Two control persons who matched for age, gender, living place (urban/rural) and region were selected for each case. All subjects were evaluated for PPK by dermatologist. Evaluation was graded as none, mild, evident and severe. None and mild subjects were classified as negative for PPK; and others as positive. Relationship between ESCC and PPK was evaluated with odds ratios and confidence intervals for cases with or without family history of ESCC.

RESULTS

The PPK frequencies were 92.3% in ESCC cases with family history, 62.5% in ESCC cases without family history, 70.8% in all ESCC cases, and 28.1% in the control group. Odds ratios for cases with or without family history of esophageal cancer, and for the whole case group were found as 30.7 (95%CI = 3.8-247.4), 4.3 (95%CI = 1.9-9.8) and 6.2 (95%CI = 2.9-13.3) respectively.

CONCLUSION

Presence of PPK lesions represents genetic susceptibility for ESCC. This susceptibility for ESCC is the highest among those who have PPK lesions and a positive family history of esophageal cancer. Furthermore, a PPK sufferer has an increased risk of developing ESCC even if there is no family history of esophageal cancer.

Risk of prostate cancer and family history of cancer: a population-based study in China

We evaluated prostate cancer risk and family history of cancers using data from a case-control study in China. Cancer information among first-degree relatives was collected from 709 subjects (238 cases and 471 controls). None of the subjects reported a family history of prostate cancer. However, excess prostate cancer risk was associated with a family history of any cancer (OR = 1.79, 95% CI: 1.21-2.63) and esophageal cancer (OR = 2.39, 95% CI: 1.15-5.00). Nonsignificant risk was seen for family history of cancers of the stomach, lung, and female breast. Our results did not confirm the familial tendency toward prostate cancer but other cancers prevalent in China appeared to be aggregate, particularly esophageal cancer. Larger studies are needed to confirm these findings, and to clarify the genetic and lifestyle factors that may be involved.

A study to determine plasma antioxidant concentrations in patients with Barrett's oesophagus

BACKGROUND

Dietary questionnaire studies have suggested that patients with oesophageal adenocarcinoma are deficient in antioxidants. It is not known whether the same holds true for patients with the precursor lesion, Barrett's oesophagus.

AIMS

To evaluate the hypothesis that patients with Barrett's oesophagus are deficient in antioxidants compared with patients without evidence of Barrett's oesophagus.

PATIENTS AND METHODS

Plasma antioxidant profiles (copper, selenium, zinc; vitamins A, C, and E; carotenoids) were determined for patients with Barrett's oesophagus (n = 36), patients with erosive oesophagitis (n = 32), and patient controls (n = 35).

RESULTS

Patients with Barrett's oesophagus had significantly lower plasma concentrations of selenium, vitamin C, beta cryptoxanthine, and xanthophyll compared with the other groups.

CONCLUSIONS

This study confirms the hypothesis that patients with Barrett's oesophagus are deficient in certain antioxidants.

Significant increase in risk of gastroesophageal cancer is associated with interaction between promoter polymorphisms in thymidylate synthase and serum folate status

Thymidylate synthase (TS) catalyzes the 5,10-methylene-tetrahydrofolate-mediated conversion of deoxyuridine monophosphate to deoxythymydine monophosphate, a nucleotide required for DNA synthesis and repair. The impaired TS expression has been shown to be related to 28 bp tandem repeats and a G-->C SNP in the 5'-UTR of TS. Folate deficiency has been demonstrated to play a role in gastroesophageal carcinogenesis. This case-control study was to examine the hypothesis that the TS polymorphisms, alone or in combination with serum folate status, may confer susceptibility of the hosts to gastroesophageal cancer. We analyzed TS genotype and serum folate concentration in 324 patients with esophageal squamous cell carcinoma (ESCC), 231 patients with gastric cardia adenocarcinoma (GCA) and 492 controls. It was found that compared with the normal expression TS genotype, the low expression TS genotype alone was significantly associated with increased risk of ESCC [adjusted odds ratio (OR) 1.47; 95% confidence interval (CI) 1.03-2.10] but not GCA (OR=0.98, 95% CI=0.68-1.40). More importantly, a significant interaction between the TS polymorphisms and serum folate status in risk of ESCC and GCA was observed. Among subjects with low serum folate concentration (<3 ng/ml), the ORs of ESCC and GCA for the low expression genotype were 22.63 (95% CI=10.44-49.05) and 4.08 (95% CI=1.94-8.59), which were greater than respective 9.97 (95% CI=5.67-17.53) and 1.88 (95% CI=1.18-3.24) for the normal expression genotype (P=0.002 and 0.029). These results suggest an important role for folate deficiency and impaired TS activity in the etiology of ESCC and GCA.

Effects of folic acid on epithelial apoptosis and expression of Bcl-2 and p53 in premalignant gastric lesions

AIM: To evaluate the effects of folic acid on epithelial apoptosis and expression of Bcl-2 and p53 in the tissues of premalignant gastric lesions.

METHODS: Thirty-eight patients, with premalignant gastric lesions including 18 colonic-type intestinal metaplasia (IM) and 20 mild or moderate dysplasia, were randomly divided into a treatment group (n = 19) receiving folic acid 10 mg thrice daily and a control group (n = 19) receiving sucralfate 1000 mg thrice daily for 3 mo. All patients underwent endoscopies and four biopsies were taken prior to treatment and repeated after concluding therapy. Folate concentrations in gastric mucosa were measured with chemiluminescent enzyme immunoassay. Epithelial apoptosis and the expression of Bcl-2 and p53 protein in gastric mucosa were detected with flow cytometric assay.

RESULTS: The mean of folate concentration in gastric mucosa was 9.03±3.37 μg/g wet wt in the folic acid treatment group, which was significantly higher than 6.83±3.02 μg/g wet wt in the control group. Both the epithelial apoptosis rate and the tumor suppressor p53 expression in gastric mucosa significantly increased after folic acid treatment. In contrast, the expression of Bcl-2 oncogene protein decreased after folic acid therapy.

CONCLUSION: These data indicate that folic acid may play an important role in the chemoprevention of gastric carcinogenesis by enhancing gastric epithelial apoptosis in the patients with premalignant lesions.

Independent and combined effects of alcohol intake, tobacco smoking and betel quid chewing on the risk of esophageal cancer in Taiwan

A multicenter case-control study was conducted in northern and southern Taiwan to clarify the independent and combined effects of alcohol intake, tobacco smoking and betel quid chewing on the risk of esophageal cancer. A total of 513 patients with newly diagnosed and histopathologically confirmed squamous cell carcinoma of the esophagus and 818 gender, age and study hospital-matched controls were included. We found a significant dose-response relationship between the duration and intensity of consumption of the 3 substances and the development of this neoplasm in this site. Although the amount of alcohol consumed had a stronger effect on the risk of esophageal cancer than the number of years it was consumed, however, the number of years one smoked had a stronger effect on the risk than the amount of cigarettes consumed. The strongest risk factor of esophageal cancer was alcohol intake, with highest risk (OR = 13.9) being for those who consumed more than 900 g/day-year. Combined exposure to any 2 of 3 substances brought the risks up to 8.8-19.7 fold and, to all 3 substances, to 41.2-fold. A multiplicative interaction effect for alcohol drinkers who smoked on cancer risk was detected, whereas an additive interaction effect was found among drinkers who chewed. The combined effect of all 3 substances accounted for 83.7% of the attributable fraction of contracting esophageal cancer in this population. In conclusion, these results suggest that the intensity and the length of time alcohol and tobacco are used play different roles in the etiology of esophageal cancer. Alcohol separately interacts with tobacco and betel quid in a differently synergistic way in determining the development of this site of cancer.

Prospective study of risk factors for esophageal and gastric cancers in the Linxian general population trial cohort in China

Esophageal cancer incidence and mortality rates in Linxian, China are among the highest in the world. We examined risk factors for esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), and gastric noncardia cancer (GNCC) in a population-based, prospective study of 29,584 adults who participated in the Linxian General Population Trial. All study participants completed a baseline questionnaire that included questions on demographic characteristics, personal and family history of disease, and lifestyle factors. After 15 years of follow-up, a total of 3,410 incident upper gastrointestinal cancers were identified, including 1,958 ESCC, 1,089 GCC and 363 GNCC. Cox proportional hazard models were used to estimate risks. Increased age and a positive family history of esophageal cancer (including ESCC or GCC) were significantly associated with risk at all 3 cancer sites. Additional risk factors for ESCC included being born in Linxian, increased height, cigarette smoking and pipe smoking; for GCC, male gender, consumption of moldy breads and pipe smoking; and for GNCC, male gender and cigarette smoking. Protective factors for ESCC included formal education, water piped into the home, increased consumption of meat, eggs and fresh fruits and increased BMI; for GCC, formal education, water piped into the home, increased consumption of eggs and fresh fruits and alcohol consumption; and for GNCC, increased weight and BMI. General socioeconomic status (SES) is a common denominator in many of these factors and improving SES is a promising approach for reducing the tremendous burden of upper gastrointestinal cancers in Linxian.

The role of vegetable and fruit consumption in the aetiology of squamous cell carcinoma of the oesophagus: A case-control study in Uruguay

There is strong evidence of a protection of high consumption of plant foods against squamous cell carcinoma of the oesophagus, but the respective role of fruits and vegetables is not well elucidated. In the time period 1996-2003, a case-control study designed in order to address this question was conducted in Uruguay. The study included 200 cases and 400 age- and sex-matched controls. High total vegetable and total fruit consumption was the strongest protective food group for this malignancy (OR 0.31, 95% CI 0.18-0.51). When this food group was dissected in total vegetables and total fruits, the latter item was more protective than the former one (OR for total fruits 0.48, 95% CI 0.35-0.66) (p-value for difference between both variables 0.04). Finally, when total fruits were dissected in citrus fruits and other fruits, citrus fruits were strongly associated with a reduction in risk (OR 0.47, 95% CI 0.34-0.67). The results of our study point towards an important role of fruits in the prevention of squamous cell carcinoma of the oesophagus.

Diagnosis of oesophageal cancer by detection of minichromosome maintenance 5 protein in gastric aspirates

Symptomatic oesophageal cancer is usually advanced and the prognosis poor. Lethality of symptomatic oesophageal cancer has motivated screening for these diseases earlier in their evolution, but reliable methods for early diagnosis remain elusive. We have demonstrated that dysregulated expression of minichromosome maintenance (MCM) proteins 2-7 is characteristic of early epithelial carcinogenesis, and that these key DNA replication initiation factors can be used as diagnostic markers for cervical and genito-urinary tract cancer. In this study, we investigated whether minichromosome maintenance protein 5 (Mcm5) can be used to detect oesophageal cancer cells in gastric aspirates. Two monoclonal antibodies raised against His-tagged human Mcm5 were used in a time-resolved immunofluorometric assay to measure Mcm5 levels in cells isolated from gastric aspirates of 40 patients undergoing gastroscopy for suspected or known oesophageal carcinoma or symptoms of dyspepsia. The test discriminated with high specificity and sensitivity between patients with and without oesophageal cancer (85% sensitivity (95% confidence interval (CI)=62-97%), 85% specificity (CI=66-96%)), as demonstrated by the large area under the receiver operating characteristics curve (0.93 (95% CI=0.85-0.99)). Elevated levels of Mcm5 in gastric aspirates are highly predictive of oesophageal cancer. This simple test for oesophageal cancer is readily automated with potential applications in primary diagnosis, surveillance and screening.

Identification of genetic variants in base excision repair pathway and their associations with risk of esophageal squamous cell carcinoma

The etiology of esophageal squamous cell carcinoma (ESCC) has been shown to be associated with genetic and certain environmental factors that produce DNA damage. Base excision repair (BER) genes are responsible for repair of DNA damage caused by reactive oxygen species and other electrophiles and therefore are good candidate susceptibility genes for ESCC. We first screened eight BER genes for new and potential functional polymorphisms by resequencing 27 DNA samples. We then identified and genotyped for important tagging single nucleotide polymorphisms (SNPs) in a case-control study of 419 patients with newly diagnosed esophageal cancer and 480 healthy controls by frequency matching on age and sex. The association between genotypes and ESCC risk was estimated by unconditional multivariate logistic regression analysis, and stepwise regression procedure was used for constructing the final logistic regression model. We identified 129 SNPs in the eight BER genes, including 18 SNPs that cause amino acid changes. In the final model, 4 SNPs, including 2 in the coding regions (ADPRT Val762Ala and MBD4 Glu346Lys) and others in noncoding regions (LIG3 A3704G and XRCC1 T-77C), remained as significant predictors for the risk of ESCC. The adjusted odd ratios were 1.25 [95% confidence interval (CI) 1.02-1.53] for the ADPRT 762Ala allele, 1.25 (95% CI 1.02-1.53) for the MBD4 346 Lys allele, 0.78 (95% CI 0.63-0.97) for the LIG3 3704G allele, and 1.38 (95% CI 1.01-1.89) for the XRCC1-77C allele. In addition, we observed a significant gene-gene interaction between XRCC1 Gln399Arg and ADPRT Val762Ala. The results suggest that the polymorphisms in five BER genes may be associated with the susceptibility to ESCC in a Chinese population.

Diet and oral, pharyngeal, and esophageal cancer

Cancers of the upper digestive tract, including those arising in the oral cavity, pharynx, and esophagus, present a significant public health problem worldwide. These cancers are associated with high morbidity and mortality, and identification of protective factors is very important. A number of epidemiological studies have examined the association between vegetables, fruits, carotene, vitamin A, vitamin C, and vitamin E and oral, pharyngeal, and esophageal cancers. The results of 35 epidemiological studies, including one prospective cohort study, one nested case-control study, two randomized controlled trials, nine population-based case-control studies, and 22 hospital-based case-control studies, in addition to in vitro and animal studies, were examined to determine whether the criteria for causal assumption were satisfied for a protective role of these dietary components against development of oral, pharyngeal, and esophageal cancers. There is enough evidence to point to a preventive role of vegetable intake, including green vegetables, cruciferous vegetables, and yellow vegetables, total fruit intake, and citrus fruit intake. Yellow fruits are likely to be protective. Carotene, vitamin C, and vitamin E are protective, most likely in combination with each other and other micronutrients. The role of vitamin A is not clear because of conflicting findings in the studies reviewed.

Food groups and risk of squamous cell carcinoma of the oesophagus: a case-control study in Uruguay

In the time period January 1998-December 2000, a case-control study on squamous cell cancer of the oesophagus was conducted in Montevideo, Uruguay. The main objective of the study was to estimate the odds ratios (ORs) associated with main food groups. For this purpose, 166 patients afflicted with squamous cell oesophageal cancer and 664 hospitalised controls were frequency matched on age and sex. Both series of patients were administered with a structured questionnaire. Aside from queries related with tobacco smoking, alcohol drinking and maté drinking, patients were interviewed with a food-frequency questionnaire (FFQ) on 64 items, representative of the usual Uruguayan diet. Red meat, salted meat and boiled meat displayed strong direct associations (OR for red meat 2.4, 95% CI 1.4-4.2). On the other hand, fish and total white meat showed moderate protective effect (OR for total white meat 0.5, 95% CI 0.3-0.9). Total fruit intake displayed a strong inverse association (OR 0.2, 95% CI 0.1-0.4), whereas total vegetable consumption presented a weak inverse association (OR for total vegetable intake 0.7, 95% CI 0.4-1.2). These results suggest that vegetables, mainly cooked vegetables, are rich in thermolabile protective substances. On the other hand, boiled (stewed) meat, which is ingested at high temperature could be, like maté, a risk factor for squamous cell cancer of the oesophagus.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

The beverage maté: a risk factor for cancer of the head and neck

BACKGROUND

Maté is a tealike beverage consumed habitually in South America and among South Americans throughout the world. It is brewed from the dried leaves and stemlets of the perennial tree Ilex paraguariensis (yerba maté), a species that belongs to the Aquifoliaceae family. Maté consumption has been associated with an increased rate of oral, oropharyngeal, esophageal, and laryngeal cancers. The purpose of this study is to review the literature and discuss the role of Maté consumption as a risk factor for head and neck cancers.

MATERIALS AND METHODS

We performed a thorough review of the relevant literature linking maté consumption with head and neck cancer and the proposed carcinogenicity of maté. Case control studies on maté-drinking populations and in vivo and in vitro studies on the carcinogenicity of maté were reviewed. The populations included in many of these studies also used alcohol and tobacco products, confounding the influence of maté as an independent risk factor.

RESULTS

Evidence in the literature suggests that maté consumption is carcinogenic and plays a role in the development of cancers of the oral cavity, pharynx, larynx, and esophagus.

CONCLUSIONS

The exact mechanism of carcinogenesis of maté is unknown. Both chemical and thermal carcinogenesis mechanisms have been suggested. Available information suggests that maté drinking is a risk factor for upper aerodigestive tract cancer.

Viral load of HPV in esophageal squamous cell carcinoma

We previously reported the presence of HPV DNA in esophageal squamous cell carcinoma (ESCC) cases from Hong Kong and Sichuan. The role of HPV in the carcinogenesis of ESCC remains unclear, partly due to the large variations in infection rates reported by different studies. While some of these variations may truly reflect different HPV infection rates in ESCC among different geographic regions, differences in sensitivity and specificity of the detection methods used also contribute. In the present study, we used quantitative real-time PCR to determine the copy numbers of HPV-16 and HPV-18 in ESCC from 5 different regions of China with different incidence rates of ESCC. Conforming to our previous reports, HPV infection was detected in 2-22.2% of samples. Infection with HPV-16 was again shown to be more common than that with HPV-18 among Chinese ESCC patients. The copy number of HPV-16 in these ESCC cases ranged from < or =1 to 157 copies/genome equivalent, with 65% of samples harboring fewer than 10 copies/genome equivalent. The median copy number of HPV-18 was 4.9/genome equivalent. Assays were validated using cervical carcinoma cell lines with known copy numbers of HPV-16 or HPV-18. The relatively low HPV copy number and infection rate in ESCC suggest that HPV is unlikely to play as essential a role in the carcinogenesis of ESCC as in cervical cancer. However, with the consistent detection of oncogenic HPVs in ESCC from some regions of China, the possibility of HPV infection being one of the multiple risk factors of ESCC in some geographic areas cannot be excluded.

Glutathione-S-transferases M1 (GSTM1) and GSTT1 genotype, smoking, consumption of alcohol and tea and risk of esophageal and stomach cancers: a case-control study of a high-incidence area in Jiangsu Province, China

To evaluate interactions between lifestyle factors and glutathione-S-transferases M1 (GSTM1) and GSTT1 genotypes with reference to development of esophageal and stomach cancers, we conducted a case-control study of 141 cases of esophageal cancer, 153 cases of stomach cancer and 223 population-based controls in Huaian City of Jiangsu Province, China. GSTM1 and GSTT1 genotypes were identified by multiplex polymerase chain reaction. The GSTM1 null genotype was associated with an increased odds ratio for esophageal cancer (2.17, 95% confidence interval=1.35-3.50), but not for stomach cancer. A combined effect was also observed between smoking and the GSTM1 null genotype with regard to esophageal risk. Tea drinking was a protective factor for both cancers, its effect being independent of the GSTT1 and GSTM1 genotypes. These findings suggest the GSTM1 polymorphism is involved in the susceptibility to esophageal cancer development, and tea consumption reduces the risk of esophageal and stomach cancers.

Vegetables, fruits, related dietary antioxidants, and risk of squamous cell carcinoma of the esophagus: a case-control study in Uruguay

In 1998-1999, a case-control study on esophageal cancer was conducted in Uruguay. For this purpose, 111 cases with squamous cell carcinoma of the esophagus and 444 controls with conditions unrelated to tobacco smoking, alcohol drinking, or recent changes in the diet were frequency matched on age, gender, residence, and urban/rural status. Vegetables and, more markedly, fruits were associated with strong reductions in risk. On the other hand, 12 of 15 dietary antioxidants displayed significant inverse associations with esophageal cancer risk. The strongest effect was observed for high intake of beta-cryptoxanthin (odds ratio = 0.16, 95% confidence interval = 0.08-0.36). Also, alpha-carotene, lycopene, and beta-sitosterol were associated with significant reductions in risk. Most antioxidants lost their effect when they were further adjusted for a term for all vegetables and fruits. beta-Carotene showed an increased risk with high intakes. On the other hand, vegetables and fruits remained as significant variables after adjustment for each antioxidant, suggesting that other substances or other mechanisms could explain this effect.

Dietary protective and risk factors for esophageal and stomach cancers in a low-epidemic area for stomach cancer in Jiangsu Province, China: comparison with those in a high-epidemic area

Comparative epidemiological studies with ecological and case-control approaches in high- and low-epidemic areas of China have provided us with much evidence with regard to risk and benefit in the environment. To clarify how dietary factors are involved in esophageal and stomach cancer development, we performed a case-control study in a low-epidemic area, and compared the findings with those obtained earlier for a high-epidemic area for stomach cancer in the same Jiangsu Province, China. We recruited 199 and 187 cases with esophageal and stomach cancers, respectively, and 333 population-based common controls. Odds ratios (ORs) for esophageal and stomach cancers were calculated with adjustment for potential confounding factors, using an unconditional logistic model. Current and former smoking elevated the OR for esophageal cancer, along with high intake of pickled vegetables and broiled meat, while decreased ORs were observed for frequently consumed raw vegetables and garlic. With regard to stomach cancer, ORs were increased with frequent consumption of salty fish, leftover gruel, and broiled meat, and lowered by snap bean consumption. The present risk factors were common to the previously obtained results in the high-epidemic area, and similarly distributed in each general population. While more protective factors were observed in the high-epidemic area, their penetrance was much greater in the low-epidemic area. The present study thus suggests that frequent vegetable and garlic consumption contributes to low mortality rates for esophageal and stomach cancers in a low-epidemic area, counteracting similar exposure levels for risk factors as in the high-epidemic area.