Prospective study of serum cysteine levels and oesophageal and gastric cancers in China.

BACKGROUND: Cancers of the upper gastrointestinal tract remain a significant cause of morbidity and mortality. Cysteine, known to be involved in a myriad of immuno-modulatory, anti-oxidant, and anti-carcinogenic pathways, has not been investigated in the aetiology of oesophageal or gastric cancers. To examine the relationship between serum cysteine concentration and risk of these cancers we conducted a nested case-cohort study within the General Population Nutrition Intervention Trial in Linxian, China. METHODS: 498 oesophageal squamous cell carcinomas (OSCCs) and 255 gastric cardia adenocarcinomas (GCAs) were matched by age and sex to 947 individuals from the wider cohort. We calculated HRs and 95% CIs using the case-cohort estimator for the Cox proportional hazards models, stratified on age and sex, with adjustment for potential confounders. RESULTS: Higher concentrations of serum cysteine were significantly associated with a lower risk of both OSCC and GCA. For those in the highest quartile of serum cysteine, compared to those in the lowest, the multivariate HRs were 0.70 for OSCC (95% CI 0.51 to 0.98) and 0.59 for GCA (95% CI 0.38 to 0.91). These associations were dose dependent (p for trend=0.006 and 0.008, respectively). These inverse associations were not significantly modified by other risk factors, with the exception of age, where a stronger association was noted among persons in the older age strata. CONCLUSION: Higher serum concentrations of cysteine were associated with a significantly reduced risk of OSCC and GCA. Cysteine should be further investigated for its potential as a chemopreventive agent for upper gastrointestinal cancers.

A prospective study of polymorphisms of DNA repair genes XRCC1, XPD23 and APE/ref-1 and risk of stroke in Linxian, China.

BACKGROUND: Stroke is the leading cause of death in Linxian, China. Although there is evidence of DNA damage in experimental stroke, no data exist on DNA repair and stroke in human populations. AIM: To assess the risk of stroke conferred by polymorphisms in the DNA repair genes, XRCC1, XPD23 and APE/ref-1 in a cohort of individuals originally assembled as subjects in two cancer prevention trials in Linxian, China. METHODS: The subjects for this prospective study were sampled from a cohort of 4,005 eligible subjects who were alive and cancer free in 1991 and had blood samples available for DNA extraction. Using real-time Taqman analyses, all incident cases of stroke (n = 118) that developed from May 1996, and an age- and a sex-stratified random sample (n = 454) drawn from all eligible subjects were genotyped. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% CIs. RESULTS: No association was observed between polymorphisms in APE/ref-1 codon 148 and XRCC16 codon 194, and stroke. Polymorphisms in XRCC110 codon 399 were associated with a significantly reduced risk of stroke (RR 0.59, 95% CI 0.36 to 0.96, p = 0.033), whereas XPD23 codon 312 was associated with a significantly increased risk of stroke (RR 2.18, 95% CI 1.14 to 4.17, p = 0.010). CONCLUSIONS: Polymorphisms in DNA repair genes may be important in the aetiology of stroke. These data should stimulate research on DNA damage and repair in stroke.

Lung cancer chemoprevention: a randomized, double-blind trial in Linxian, China.

We examined the effect of supplementation with four different combinations of vitamins and minerals in the prevention of lung cancer mortality among 29,584 healthy adults from Linxian, China. In accord with a partial factorial design, the participants were randomly assigned to take either a vitamin/mineral combination or a placebo for 5.25 years. The combinations tested in this trial were as follows: factor A, retinol and zinc; factor B, riboflavin and niacin; factor C, ascorbic acid and molybdenum; factor D, beta-carotene, alpha-tocopherol, and selenium. Lung cancer deaths (n = 147) identified during the trial period (1986-1991) and 10 years after the trial ended (1991-2001) were the study outcome. No significant differences in lung cancer death rates were found for any of the four combinations of supplements tested in this study, using log-rank tests (all P values are >0.20) or Cox proportional hazards models adjusted for age, sex, commune, and other treatments. No significant interactions were seen for age, sex, or smoking status. Supplementation with combinations of vitamins and minerals at nutrient-repletion levels for 5.25 years did not reduce lung cancer mortality in this nutrient-inadequate population in Linxian, China.

Tooth loss is associated with increased risk of total death and death from upper gastrointestinal cancer, heart disease, and stroke in a Chinese population-based cohort.

BACKGROUND: Tooth loss has previously been associated with a higher risk of cancer, heart disease, and stroke, but the role of confounding by smoking remains an issue. METHODS: We conducted a cohort study including 29,584 healthy, rural Chinese adults who were participants in a chemoprevention trial from 1986 through 1991 and who have been followed-up through 2001. We categorized tooth loss for each subject as less than or equal to or greater than the median number of teeth lost for other subjects of the same age at baseline. Mortality outcomes were categorized as follows: total death (n = 9362), upper gastrointestinal (GI) cancer death (n = 2625), other cancer death (n = 514), heart disease death (n = 1932), and fatal stroke (n = 2866). RESULTS: Individuals with greater than the age-specific median number of teeth lost had statistically significant 13% increased risk of total death [95% confidence interval (CI) 9-18%], 35% increased risk of upper GI cancer death (95% CI 14-59%), 28% increased risk of heart disease death (95% CI 17-40%), and 12% increased risk of stroke death (95% CI 2-23%), but no significantly increased risk of death from cancer at other sites. These elevated risks were present in male smokers, male non-smokers, and females, nearly all never-smokers. CONCLUSIONS: In this Asian population, tooth loss significantly increased the risk of total death and death from upper GI cancer, heart disease, and stroke. These associations were not limited to tobacco smokers.

Prospective study of serum selenium concentrations and esophageal and gastric cardia cancer, heart disease, stroke, and total death.

BACKGROUND: We previously reported an inverse association between prediagnostic serum selenium concentrations and the risk of esophageal squamous cell carcinoma (ESCC) and gastric cardia cancer (GCC) but not gastric noncardia cancer (GNCC) in a nested study from the Nutrition Intervention Trial in Linxian, China. OBJECTIVE: We examined the relation between baseline serum selenium and the subsequent risk of death from ESCC, GCC, GNCC, heart disease (HD), stroke, and total death over 15 y of follow-up (1986-2001). DESIGN: We measured baseline serum selenium concentrations in 1103 subjects randomly selected from a larger trial cohort. We identified 516 deaths during the 15-y follow up, including 75 from ESCC, 36 from GCC, 116 from HD, and 167 from stroke. Relative risks (RRs) and 95% CIs were estimated by using Cox proportional hazards regression models. Reported RRs estimated the change in risk conferred by a 25% increase in serum selenium relative to the population distribution. All estimates were adjusted for sex, age, smoking, drinking, and serum cholesterol. RESULTS: We found significant inverse associations between baseline serum selenium and death from ESCC (RR: 0.83; 95% CI: 0.71, 0.98) and GCC (0.75; 0.59, 0.95). Trends toward inverse associations were noted for death from HD (0.89; 0.78, 1.01; P = 0.07), but no association was noted for total death (0.96; 0.90, 1.02) or stroke (0.99; 0.88, 1.11). CONCLUSION: Population-wide selenium supplementation in the region of China with low serum selenium and high incidences of ESCC and GCC merits serious consideration.

Variants of the IL8 and IL8RB genes and risk for gastric cardia adenocarcinoma and esophageal squamous cell carcinoma.

The population of Linxian in north central China is at high risk for gastric cardia adenocarcinoma (GCC) and esophageal squamous cell carcinoma (ESCC), and chronic inflammation may contribute to this risk. Interleukin-8 (IL8), a potent chemoattractant, has three well-characterized single nucleotide polymorphisms (SNP), one (-251) of which alters transcriptional activity. Four well-described SNPs in the two IL8 receptors, IL8RA and IL8RB, have been associated with inflammation. We conducted a case-cohort study in the Nutrition Intervention Trials (Linxian, China) to assess the association between these SNPs and incident GCC (n = 90) and ESCC (n = 131). IL8, IL8RA, and IL8RB SNPs were analyzed using a multiplex assay system, haplotypes were constructed, and risks were estimated using Cox proportional hazards models. The homozygous variants of IL8 -251 and +396 were associated with 2-fold increased relative risks for GCC, but the highest risk observed was for the AGT/AGC haplotype of IL8 -251/+396/+781 (relative risk, 4.14; 95% confidence interval, 1.31-13.1). Variation within IL8 was not associated with ESCC. Few subjects had variation at the IL8RA SNP and no significant associations were observed for IL8RB SNPs or haplotypes with either GCC or ESCC. We conclude that variation in IL8 seems to increase the risk for GCC but not ESCC in this high-risk population. These variants could confer an altered IL8 expression pattern or interact with environmental factors to increase the risk for inflammation and GCC.

Esophageal and gastric cardia cancer risk and folate- and vitamin B(12)-related polymorphisms in Linxian, China.

Linxian, a rural county in North Central China, has among the highest rates of esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) in the world. Its inhabitants have documented chronic nutritional inadequacies, including folate and vitamin B(12) deficiencies. Using a cohort we have been studying in Linxian since 1985, we examined the relationship between incident ESCC and GCA cancers and three polymorphisms in two genes that code for enzymes that require folate and B(12) as cofactors: methionine synthase reductase (MTRR) A66G and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C. We conducted a case-cohort study among 4005 individuals in our cohort who were alive and cancer free in 1991 and had blood samples adequate for DNA extraction. Polymorphisms were measured on all 219 incident cancers (129 ESCCs and 90 GCAs) that developed through May 1996 and on 398 controls. Cox proportional hazard models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs). Individuals with the MTHFR 677TT genotype had significantly higher combined ESCC/GCA risks (RR, 1.45; 95% CI, 1.02-2.05) than those with CC or CT genotypes. The only subjects to have MTHFR 1298CC were three ESCC cases (P = 0.03). Compared with subjects with the MTRR 66AA genotype, subjects with the AG or GG genotypes had significantly higher risk of ESCC (RR, 1.59; 95% CI, 1.04-2.42). No association was observed for GCA. Our results suggest that the MTHFR C677T and MTRR A66G polymorphisms influence the risk of ESCC and GCA in this population.

Polymorphisms of XRCC1 and risk of esophageal and gastric cardia cancer.

BACKGROUND: Linxian, a rural county in North Central China, has among the highest rates of esophageal squamous cell carcinoma and gastric cardia adenocarcinoma in the world. In a nested case-cohort study that originated from two cancer prevention trials in Linxian, we examined the relationship between these cancers and two polymorphisms in the DNA repair gene XRCC1. METHODS: We conducted a case-cohort study among individuals in the cohort who were alive and cancer free in 1991, and had blood samples for DNA extraction. Real time Taqman analyses were conducted to genotype incident cancer cases (n = 221, 131 esophageal and 90 gastric cardia cancer cases) that developed through May 1996, and on an age- and sex-matched reference cohort (n = 454). We used Cox proportional hazard models to estimate relative risks (RR) and 95% confidence intervals (95% CI). RESULTS: We observed no association between the variant genotype in XRCC1 Arg194Trp (codon 194 arganine to tryptophan substitution) and esophageal or gastric cardia cancer. However, carrying at least one copy of the variant allele in XRCC1 Arg399Gln (codon 399 arganine to glutamine substitution) was associated with reduced risk of gastric cardia cancer (RR: 0.60, 95% CI: 0.37-0.97) and the combined category esophageal/gastric cancer (RR: 0.67, 95% CI: 0.48-0.95). In combined polymorphisms analyses, we observed a significant reduction in risk of combined esophageal/gastric cancer among individuals that had both the XRCC1 Arg194Trp and Arg399Gln variant genotyopes (RR: 0.47, 95% CI: 0.26-0.84). CONCLUSIONS: Our results suggest that the XRCC1 Arg399Gln variant genotype is associated with reduced risk of upper GI cancer and that individuals with both XRCC1 variant genotypes are also at significantly reduced risk of upper GI cancer in this high-risk Chinese population.

Seasonal variation of food consumption and selected nutrient intake in Linxian, a high risk area for esophageal cancer in China.

Linxian, China, is a region with high incidence of esophageal cancer and a history of poor nutritional status. Nutrition Intervention Trials were conducted in this area from 1985 through 1991 and found a reduction in total cancer mortality in the group receiving supplementation of beta-carotene/selenium/alpha-tocopherol. The positive results of those trials have, in part, been ascribed to the poor nutritional status of this population. To investigate more recent food patterns, nutrient intakes, and seasonal variations in the diet, dietary surveys were conducted among the residents of Linxian in 1996. Food consumption data were collected among 104 households in spring and 106 households in autumn using a method of food inventory changes. Intake of nutrients was estimated and compared to the Chinese Recommended Dietary Allowance (RDA). In both seasons, the five most common food groups consumed were cereals, fresh vegetables, yams, seasoning, and eggs. Low nutrient intakes were found for selenium (79% RDA and 66% RDA), zinc (72% RDA and 62% RDA), vitamin B2 (64% RDA and 52% RDA), and calcium (53% RDA and 39% RDA) in both spring and autumn. A large seasonal variation was seen in the consumption of leafy vegetables, root vegetables and eggs, all of which might have contributed to the lower intake of vitamin A (25% RDA), vitamin C (75% RDA), protein (76% RDA), and vitamin E (78% RDA) in autumn. These indicate that the nutrient intake in Linxian is inadequate for a number of vitamins and minerals including those shown to be associated with esophageal cancer.

Total and cancer mortality after supplementation with vitamins and minerals: follow-up of the Linxian General Population Nutrition Intervention Trial.

BACKGROUND: The General Population Nutrition Intervention Trial was a randomized primary esophageal and gastric cancer prevention trial conducted from 1985 to 1991, in which 29,584 adult participants in Linxian, China, were given daily vitamin and mineral supplements. Treatment with "factor D," a combination of 50 microg selenium, 30 mg vitamin E, and 15 mg beta-carotene, led to decreased mortality from all causes, cancer overall, and gastric cancer. Here, we present 10-year follow-up after the end of active intervention. METHODS: Participants were assessed by periodic data collection, monthly visits by village health workers, and quarterly review of the Linxian Cancer Registry. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the cumulative effects of four vitamin and mineral supplementation regimens were calculated using adjusted proportional hazards models. RESULTS: Through May 31, 2001, 276 participants were lost to follow-up; 9727 died, including 3242 from cancer (1515 from esophageal cancer and 1199 from gastric cancer). Participants who received factor D had lower overall mortality (HR = 0.95, 95% CI = 0.91 to 0.99; P = .009; reduction in cumulative mortality from 33.62% to 32.19%) and gastric cancer mortality (HR = 0.89, 95% CI = 0.79 to 1.00; P = .043; reduction in cumulative gastric cancer mortality from 4.28% to 3.84%) than subjects who did not receive factor D. Reductions were mostly attributable to benefits to subjects younger than 55 years. Esophageal cancer deaths between those who did and did not receive factor D were not different overall; however, decreased 17% among participants younger than 55 (HR = 0.83, 95% CI = 0.71 to 0.98; P = .025) but increased 14% among those aged 55 years or older (HR = 1.14, 95% CI = 1.00 to 1.30; P = .047) [corrected]. Vitamin A and zinc supplementation was associated with increased total and stroke mortality; vitamin C and molybdenum supplementation, with decreased stroke mortality. CONCLUSION: The beneficial effects of selenium, vitamin E, and beta-carotene on mortality were still evident up to 10 years after the cessation of supplementation and were consistently greater in younger participants. Late effects of other supplementation regimens were also observed.

Chemoprevention of primary liver cancer: a randomized, double-blind trial in Linxian, China.

BACKGROUND: Primary liver cancer is a common malignancy with a dismal prognosis. New primary prevention strategies are needed to reduce mortality from this disease. We examined the effects of supplementation with four different combinations of vitamins and minerals on primary liver cancer mortality among 29450 initially healthy adults from Linxian, China. METHODS: Participants were randomly assigned to take either a vitamin-mineral combination ("factor") or a placebo daily for 5.25 years (March 1986-May 1991). Four factors (at doses one to two times the US Recommended Daily Allowance)-retinol and zinc (factor A); riboflavin and niacin (factor B); ascorbic acid and molybdenum (factor C); and beta-carotene, alpha-tocopherol, and selenium (factor D)-were tested in a partial factorial design. The study outcome was primary liver cancer death occurring from 1986 through 2001. Adjusted Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of liver cancer death with and without each factor. All P values are two-sided. RESULTS: A total of 151 liver cancer deaths occurred during the analysis period. No statistically significant differences in liver cancer mortality were found comparing the presence and absence of any of the four intervention factors. However, both factor A and factor B reduced liver cancer mortality in individuals younger than 55 years at randomization (HR = 0.59, 95% CI = 0.34 to 1.00, and HR = 0.54, 95% CI = 0.31 to 0.93, respectively) but not in older individuals (HR = 1.06, 95% CI = 0.71 to 1.59, and HR = 1.12, 95% CI = 0.75 to 1.68, respectively). Factor C reduced liver cancer death, albeit with only borderline statistical significance in males (HR = 0.70, 95% CI = 0.47 to 1.02) but not in females (HR = 1.30, 95% CI = 0.72 to 2.37). Cumulative risks of liver cancer death were 6.0 per 1000 in the placebo arm, 5.4 per 1000 in the arms with two factors, and 2.4 per 1000 in the arm with all four factors. CONCLUSION: None of the factors tested reduced overall liver cancer mortality. However, three factors reduced liver cancer mortality in certain subgroups.

Human papillomavirus serology and the risk of esophageal and gastric cancers: results from a cohort in a high-risk region in China.

Each year, esophageal and gastric cancers cause more than 900,000 deaths worldwide. Human papilloma virus (HPV), especially type 16, has been suggested to have a role in the etiology of esophageal cancer, however, the results of previous seroepidemiological studies have not been consistent. We conducted a large prospective study to examine the association between serum antibodies to HPV 16, HPV 18 and HPV 73 and subsequent development of esophageal squamous cell carcinoma (ESCC), gastric cardia adenocarcinoma (GCA), and gastric noncardia adenocarcinoma (GNCA) in a high-risk population for these cancers in Linxian, China. Case and control subjects for this study were selected from the 29,584 participants of the Linxian General Population Trial. Prediagnostic serum samples from 99 cases of ESCC, 100 cases of GCA, 70 cases of GNCA, and 381 age- and sex- matched controls were selected for this study. The presence of antibodies to HPV virus-like particles was determined by type-specific enzyme-linked immunosorbent assays. Fewer than 15% of ESCC, GCA, or GNCA cases were positive for each HPV type, and no significant associations were found. The adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for HPV 16 seropositivity and ESCC, GCA, and GNCA risk were 1.6 (0.8-3.3), 1.3 (0.6-2.8) and 0.4 (0.1-1.6), respectively. The comparable ORs (95% CIs) for HPV 18 were 1.0 (0.4-2.2), 0.9 (0.4-2.1) and 1.5 (0.6-3.4). For HPV 73, these figures were 1.3 (0.6-2.5), 1.2 (0.6-2.3) and 0.9 (0.4-2.1). The results of this study do not support a major role for HPV 16, HPV 18 and HPV 73 in the etiology of esophageal and gastric cancers in Linxian, China.

Self-reported goiter is associated with a significantly increased risk of gastric noncardia adenocarcinoma in a large population-based Chinese cohort.

Iodine is concentrated by the gastric mucosa, where it may act as an antioxidant. Therefore, iodine deficiency, and its sequelae goiter, may be associated with an increased risk of gastric cancer. We examined the association between self-reported goiter and upper gastrointestinal cancer in a Chinese cohort of 29,584 adults. Using multivariate adjusted Cox models, we found goiter associated with a significantly increased risk of gastric noncardia adenocarcinoma, HR (95% CI) 2.04 (1.01, 4.11) and nonsignificantly with gastric cardia adenocarcinoma, HR (95% CI) 1.45 (0.91, 2.30). We also found a borderline, insignificant increased risk of esophageal squamous cell carcinoma, HR (95% CI) 1.37 (0.97, 1.94). Our findings are consistent with the hypothesis that iodine deficiency is associated with an increased risk of gastric cancer.

Serum concentrations of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and risk of primary liver cancer.

BACKGROUND: 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) exposure has been demonstrated to cause liver tumors in laboratory rodents. DDT's persistent metabolite and environmental degradation product, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), has also been associated with liver tumors in laboratory animals. Whether DDT and DDE are associated with hepatocarcinogenesis in humans is not clear. METHODS: We carried out a nested case-control study among the participants of the Nutritional Intervention Trials in Linxian, China. The case group included 168 individuals who developed liver cancer during the trials, and the control group included 385 individuals frequency-matched on age and sex who were alive and well at the end of the study. Serum concentrations of DDT and DDE were measured by gas chromatography-mass spectrometry. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multivariable analysis. RESULTS: In multivariable-adjusted models, the risk of developing liver cancer increased with increased serum DDT concentration (OR for quintile 1 versus quintile 5 = 3.8, 95% CI = 1.7 to 8.6, P(trend) = .0024). In contrast, there was no statistically significant association between liver cancer and serum DDE concentration. The association between high serum DDT concentration and liver cancer was stronger among individuals with DDE concentrations below the median value (odds ratio for tertile 3 versus tertile 1 = 3.55, 95% CI = 1.45 to 8.74) than those with concentrations above the median (OR = 1.70, 95% CI = 0.97 to 2.98). A calculation of crude liver cancer risk found that there would be 26 liver cancers per 100 000 persons per year in the lowest quintile of DDT exposure versus 46 liver cancers per 100 000 persons per year in the highest quintile of DDT exposure. CONCLUSIONS: DDT may be a risk factor for liver cancer, particularly among persons with lower DDE concentrations. Risk may be particularly increased among persons exposed directly to DDT (resulting in a higher ratio of DDT to DDE) or, alternatively, risk may be associated with individual ability to metabolize DDT to DDE.

Zinc concentration in esophageal biopsy specimens measured by x-ray fluorescence and esophageal cancer risk.

BACKGROUND: In rodents, zinc deficiency potentiates the effects of certain nitrosamines that act as esophageal carcinogens. Studies of the association between zinc and esophageal squamous cell carcinoma in humans have been hampered by plasma zinc homeostasis, which obscures individual differences in total zinc stores, and by the uncertainty regarding zinc bioavailability when estimating dietary zinc intake because phytate from whole grains effectively prohibits zinc absorption. By using baseline tissue biopsy specimens collected in a prospective observational study, we determined the association between incident esophageal squamous cell carcinoma and baseline element concentrations in tissue sections from residents of Linzhou, China, participating in a nutrition intervention trial. METHODS: We used x-ray fluorescence spectroscopy to measure zinc, copper, iron, nickel, and sulfur concentrations in single 5-microm-thick sections from formalin-fixed, paraffin-embedded esophageal biopsy specimens collected in 1985 from 60 eventual case and 72 control subjects. Subjects were matched on baseline histology and followed for 16 years. We used Cox proportional hazards models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between each element and risk of incident esophageal cancer. All statistical tests were two-sided. RESULTS: The risk of developing esophageal cancer was much lower for subjects in the highest quartile of esophageal tissue zinc concentration compared with those in the lowest quartile (HR = 0.21, 95% CI = 0.065 to 0.68). The association was statistically significant across quartiles (P(trend) = .015). Individuals in the highest quartile of sulfur concentration had a lower risk of esophageal cancer than individuals in the lowest quartile (HR = 0.29, 95% CI = 0.095 to 0.85), but the association across quartiles was not statistically significant (P(trend) = .081). There was no association between copper, iron, or nickel concentrations and risk of esophageal cancer. CONCLUSION: High tissue zinc concentration was strongly associated with a reduced risk of developing esophageal squamous cell carcinoma. X-ray fluorescence spectroscopy can be used to assess relationships among concentrations of both nutritional and toxic elements and disease risk in banked tissue specimens.

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.

Hepatitis C virus infection, Linxian, China.

Bloodborne viruses may have spread in rural China during the past 25 years, but population-based prevalence estimates are lacking. We examined the frequency of hepatitis C virus (HCV) and HIV type 1 (HIV-1) among residents of Linxian, a rural community in Henan Province. In 2000, blood was collected from participants (> or = 55 years of age) who had enrolled in a population-based nutritional intervention trial in 1985. We randomly selected 500 participants for HCV testing and 200 participants for HIV-1 testing. For HCV, 48 (9.6%) of 500 participants were positive by enzyme immunoassay and recombinant immunoblot assay (95% confidence interval, 7.0%-12.2%), and prevalence was lowest in the most geographically isolated participants. Among the HCV-infected participants, 42 had a specimen available from 1985, of which 16 (38.1%) were positive for HCV. For HIV-1, 0/200 participants were positive. We conclude that HCV is now a common infection among older adults in Linxian, China.

Toenail selenium concentration and lung cancer in male smokers (Finland).

BACKGROUND: The objective of this investigation was to evaluate the association between toenail selenium concentration and lung cancer risk in male smokers. METHODS: We conducted a nested case-control study within the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study cohort. This substudy included 250 randomly selected incident lung cancer cases and 250 controls matched on age (up to +/- 5 years), intervention group assignment, and date of randomization (+/- 15 days). Odds ratios (ORs) and 95% confidence intervals (CIs) were determined using conditional logistic regression methods. Finland began fortification of agricultural fertilizers in the fall of 1984, increasing the dietary intake, plasma, and toenail selenium concentrations for the population. The present analyses were based on the calculated residual of toenail selenium after regressing it on date of randomization. The selenium residual and the interaction of the residual with date of randomization were included in models with smoking status and body mass index as covariates. RESULTS: We observed a suggestion of a protective association for higher selenium status among men who entered the trial early (when the range of selenium values included very low levels). The OR for men with adjusted toenail selenium concentrations at the 75th percentile compared to those with the lowest selenium concentrations ranged between 0.20 (0.09-0.44) for men randomized earliest in the trial and 0.61 (0.27-1.41) for men randomized in the fifth year. CONCLUSIONS: These results suggest that low selenium status may be associated with increased risk for lung cancer.

Polymorphic variation of Cyp1A1 is associated with the risk of gastric cardia cancer: a prospective case-cohort study of cytochrome P-450 1A1 and GST enzymes.

OBJECTIVE: To determine if genetic polymorphisms of CYP1A1, GSTM1, GSTP1, or GSTT1 are associated with an increased risk of developing esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), or either in a high-risk Asian population. METHODS: We conducted a case-cohort analysis with 5 years of prospective follow-up. The analytical cohort contained 642 individuals who participated in either the Dysplasia Trial (DT) or the General Population (GPT) of the Nutrition Intervention Trials conducted in Linxian, China, and included 131 cases of ESCC and 90 cases of GCC. Genotyping analysis was performed on DNA extracted from red blood cells using a PureGene kit (Gentra Systems, Inc., Minneapolis, MN) and real-time PCR analysis amplification (Taq-Man). Relative risks and 95% confidence intervals were estimated using the case - cohort estimator for the Cox proportional hazards models. p-values from nested models with genotyping variables came from score tests. RESULTS: The relative risks for developing ESCC, GCC, or either cancer were calculated in the entire analytic cohort for GSTM1, P1*B (A313G), and T1 and CYP1A1*2A (T3801C) and *2C (A2455G) genotypes, and no significant associations were identified. However, because of the difference in cancer risks between the DT (9.3 cases per 1000 person years) and the GPT (5.3 cases), the analytical cohort was stratified by trial; the DT participants who were heterozygous or homozygous for the variant-allele at CYP1A1*2A had a reduced risk for developing GCC (adjusted RR (95% CI) 0.47 (0.23-1.00) p = 0.037). CONCLUSIONS: This study found an association for the CYP1A1*2A variant allele and a reduced risk of GCC in people at high risk for development of this disease. This finding is consistent with previous studies suggesting that substrates for the cytochrome P-450 1A1 metabolic pathway, such as polycyclic aromatic hydrocarbons, may be etiologically significant in this high-risk region.