Contribution of genetic and nutritional factors to DNA damage in heavy smokers

Prior epidemiological evidence suggests that genes controlling the metabolism of carcinogens and antioxidant/nutritional status are associated with lung cancer risk, possibly through their ability to modulate DNA damage by carcinogens. We performed a cross-sectional analysis of 159 heavy smokers from a cohort of subjects enrolled in a smoking cessation program. A total of 159 blood samples were analyzed to determine the relative contributions of genetic polymorphisms [CYP1A1 MspI and exon 7 and glutathione S-transferase M1 (GSTM1)] and plasma micronutrients to polycyclic aromatic hydrocarbon-DNA (PAH-DNA) adduct levels. DNA damage in smokers was affected by genetic polymorphisms and nutritional status. Smokers with the CYP1A1 exon 7 valine polymorphism had significantly higher (2-fold, P < or = 0.03) levels of DNA damage than those without. In parallel models, PAH-DNA adducts were inversely associated with plasma levels of retinol (beta = -0.93, P = 0.01), beta-carotene (beta = -0.18, P = 0.09), and alpha- tocopherol (beta = -0.28, P = 0.21) in 159 subjects. The association between smoking-adjusted plasma beta-carotene levels and DNA damage was only significant in those subjects lacking the GSTM1 detoxification gene (beta = -0.30, P = 0.05, n = 75). There was a statistical interaction between beta-carotene and alpha-tocopherol; when beta- carotene was low, alpha-tocopherol had a significant protective effect (beta = -0.78, P = 0.04) on adducts, but not when beta-carotene was high (beta = -0.16, P = 0.57). Plasma alpha-tocopherol was significantly correlated with beta-carotene (r = 0.36, P = 0.0005) and less strongly with retinol (r = 0.20, P = 0.0005). These results suggest that several micronutrients may act in concert to protect against DNA damage and highlight the importance of assessing overall antioxidant status. In conclusion, a subset of smokers may be at increased risk of DNA damage and possibly lung cancer due to the combined effect of low plasma micronutrients and genetic susceptibility factors. The use of biological markers to assess efficacy of interventions and to study mechanisms of micronutrients is timely given the current debate regarding the use of chemopreventive agents in high risk populations.      

The effects of diet on DNA bulky adduct levels are strongly modified by GSTM1 genotype: a study on 634 subjects

Frequent consumption of fresh fruit and vegetables, and polymorphisms in the detoxifying enzyme glutathione S-transferase M1 (GSTM1) and other metabolic genes have been shown to modulate cancer risk at some sites. We have shown recently that DNA adducts, a reliable indicator of genotoxic damage and, possibly, of cancer risk, are modulated by plasma levels of selected micronutrients. Here we further investigate the association between DNA adduct levels and consumption of major food groups and foods, and the estimated dietary intake of nutrients, taking into account the possible modifying effect of metabolic polymorphisms, in a larger sample of 634 healthy adults enrolled in a prospective study in Italy. DNA adducts and five polymorphic metabolic genotypes (GSTM1, GSTT1, NAT2, CYP1A1 and MTHFR) were determined in peripheral leukocytes by using 32P-postlabeling technique and PCR methods. DNA bulky adducts (mean: 7.82 +/- 0.40/10(9) nt) were detected in 482/634 samples (76.0%). Overall, DNA adduct levels were significantly and inversely associated with the intake of raw leafy vegetables (P = 0.02), non-citrus fruits (P = 0.04), potassium (P = 0.01) and beta-carotene (P = 0.05). No association was evident with the five genotypes. Stratification by GSTM1 genotype showed strong inverse associations of DNA adduct levels with increasing consumption of all vegetables combined (P = 0.04), leafy vegetables (P = 0.004), raw leafy vegetables (P = 0.002) and fish (P = 0.03) among 307 GSTM1-null subjects; strong inverse associations also emerged with estimated dietary intakes of beta-carotene (P = 0.004), vitamin E (P = 0.004), niacin (P = 0.02) and potassium (P = 0.01). In contrast, no association emerged among 295 subjects with a GSTM1-wild genotype. Overall, statistically significant interactions in predicting DNA adduct levels were observed between the GSTM1-null genotype and consumption of leafy vegetables (P = 0.01), white meat (P = 0.04), and intake of vitamin C (P = 0.04), vitamin E (P = 0.05) and beta-carotene (P = 0.02). Our results suggest that the role of a diet rich in antioxidants in preventing or reducing DNA adduct formation is restricted to subjects lacking the detoxifying activity of GSTM1 isoenzyme (approximately 50% of the general population).     

Plasma antioxidant vitamins, chronic hepatitis B virus infection and urinary aflatoxin B1-DNA adducts in healthy males

Epidemiological evidence indicates that aflatoxin B1 (AFB1) intake is associated with an increased risk of hepatocellular carcinoma (HCC). The hepatocarcinogenesis is initiated by covalent binding of AFB1 to cellular DNA. To determine whether nutritional factors and hormonal status may influence the binding of AFB1 to hepatic DNA, a cross- sectional study was performed on a total of 42 male asymptomatic hepatitis B surface antigen (HBsAg) carriers and 43 male non-carriers in a cohort study on the multistage development of HCC in Taiwan. The major AFB1-DNA adduct in vivo, AFB1-N7-guanine, was measured by high- performance liquid chromatography in urine. Urinary AFB1-N7-guanine was detectable in 40% of the subjects. HBsAg carriers had a higher detection rate of urinary AFB1-DNA adducts than non-carriers and the difference was statistically significant after multivariate adjustment. After taking into account the total AFB1 urinary metabolite level, chronic HBsAg carrier status, and other potential confounders, plasma levels of cholesterol, alpha-tocopherol, and alpha- and beta-carotene were positively associated with the detection rate of the AFB1-DNA adducts in a dose-dependent manner, whereas plasma lycopene level was inversely related to the presence of the adducts in urine. The association of urinary AFB1-DNA adducts with the plasma levels of cholesterol, alpha-tocopherol, lycopene, and alpha- and beta-carotene was observed at both low and high exposure levels of AFB1. There was a synergistic interaction of plasma alpha-tocopherol with alpha- and beta- carotene on the adduct levels. No association with the adducts was found for plasma levels of retinol and testosterone. This study demonstrated different associations of antioxidant vitamins with AFB1- DNA adduct formation. The data consistent with our previous finding in cultured woodchuck hepatocytes that alpha-tocopherol and beta-carotene enhanced AFB1-DNA adduct formation suggest that prospective investigation of the relationship between plasma micronutrients and risk of AFB1-related HCC is warranted.      

Plasma levels of carotenoids, retinol and tocopherol and the risk of gastric cancer in Japan: a nested case-control study

Fruits and vegetables have been suggested to confer protection against diseases such as cancer through the effects of antioxidants, often represented by carotenoids. We investigated the impact of carotenoids, retinol and tocopherol on gastric cancer development in a large nested case-control study among Japanese with known Helicobacter pylori infection status. A total of 36 745 subjects aged 40-69 in the Japan Public Health Center-based Prospective Study who responded to the baseline questionnaire and provided blood samples in 1990-1995 were followed until 2004. Plasma levels of carotenoids in 511 gastric cancer cases and 511 matched controls were measured by high-performance liquid chromatography. Odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated using conditional logistic regression models. Plasma level of beta-carotene was inversely associated with the risk of gastric cancer (compared with the lowest quartile: OR = 0.63, 95% CI = 0.31-0.75; OR = 0.48, 95% CI = 0.31-0.75 and OR = 0.46, 95% CI = 0.28-0.75, for quartile 2, 3 and 4, respectively, P(trend) < 0.01). Inverse associations were evident in men for alpha-carotene (P(trend) = 0.04) and beta-carotene (P(trend) < 0.01), but not in women, who had relatively higher plasma levels compared with men. We found no statistically significant association between plasma levels of lutein/zeaxanthin, lycopene, retinol, alpha- or gamma-tocopherol and gastric cancer risk. Our findings suggest that those who have very low plasma levels of alpha-carotene and beta-carotene are at a higher risk of gastric cancer.     

Lower prostate cancer risk in men with elevated plasma lycopene levels: results of a prospective analysis

Dietary consumption of the carotenoid lycopene (mostly from tomato products) has been associated with a lower risk of prostate cancer. Evidence relating other carotenoids, tocopherols, and retinol to prostate cancer risk has been equivocal. This prospective study was designed to examine the relationship between plasma concentrations of several major antioxidants and risk of prostate cancer. We conducted a nested case-control study using plasma samples obtained in 1982 from healthy men enrolled in the Physicians' Health Study, a randomized, placebo-controlled trial of aspirin and beta-carotene. Subjects included 578 men who developed prostate cancer within 13 years of follow-up and 1294 age- and smoking status-matched controls. We quantified the five major plasma carotenoid peaks (alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene) plus alpha- and gamma-tocopherol and retinol using high-performance liquid chromatography. Results for plasma beta-carotene are reported separately. Odds ratios (ORs), 95% confidence intervals (Cls), and Ps for trend were calculated for each quintile of plasma antioxidant using logistic regression models that allowed for adjustment of potential confounders and estimation of effect modification by assignment to either active beta-carotene or placebo in the trial. Lycopene was the only antioxidant found at significantly lower mean levels in cases than in matched controls (P = 0.04 for all cases). The ORs for all prostate cancers declined slightly with increasing quintile of plasma lycopene (5th quintile OR = 0.75, 95% CI = 0.54-1.06; P, trend = 0.12); there was a stronger inverse association for aggressive prostate cancers (5th quintile OR = 0.56, 95% CI = 0.34-0.91; P, trend = 0.05). In the placebo group, plasma lycopene was very strongly related to lower prostate cancer risk (5th quintile OR = 0.40; P, trend = 0.006 for aggressive cancer), whereas there was no evidence for a trend among those assigned to beta-carotene supplements. However, in the beta-carotene group, prostate cancer risk was reduced in each lycopene quintile relative to men with low lycopene and placebo. The only other notable association was a reduced risk of aggressive cancer with higher alpha-tocopherol levels that was not statistically significant. None of the associations for lycopene were confounded by age, smoking, body mass index, exercise, alcohol, multivitamin use, or plasma total cholesterol level. These results concur with a recent prospective dietary analysis, which identified lycopene as the carotenoid with the clearest inverse relation to the development of prostate cancer. The inverse association was particularly apparent for aggressive cancer and for men not consuming beta-carotene supplements. For men with low lycopene, beta-carotene supplements were associated with risk reductions comparable to those observed with high lycopene. These data provide further evidence that increased consumption of tomato products and other lycopene-containing foods might reduce the occurrence or progression of prostate cancer.     

Plasma and dietary carotenoid, retinol and tocopherol levels and the risk of gastric adenocarcinomas in the European prospective investigation into cancer and nutrition

Despite declining incidence rates, gastric cancer (GC) is a major cause of death worldwide. Its aetiology may involve dietary antioxidant micronutrients such as carotenoids and tocopherols. The objective of this study was to determine the association of plasma levels of seven common carotenoids, their total plasma concentration, retinol and alpha- and gamma-tocopherol, with the risk of gastric adenocarcinoma in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 countries. A secondary objective was to determine the association of total sum of carotenoids, retinol and alpha-tocopherol on GCs by anatomical subsite (cardia/noncardia) and histological subtype (diffuse/intestinal). Analytes were measured by high-performance liquid chromatography in prediagnostic plasma from 244 GC cases and 645 controls matched by age, gender, study centre and date of blood donation. Conditional logistic regression models adjusted by body mass index, total energy intake, smoking and Helicobacter pylori infection status were used to estimate relative cancer risks. After an average 3.2 years of follow-up, a negative association with GC risk was observed in the highest vs the lowest quartiles of plasma beta-cryptoxanthin (odds ratio (OR) = 0.53, 95% confidence intervals (CI) = 0.30-0.94, P(trend) = 0.006), zeaxanthin (OR = 0.39, 95% CI = 0.22-0.69, P(trend) = 0.005), retinol (OR = 0.55, 95% CI = 0.33-0.93, P(trend) = 0.005) and lipid-unadjusted alpha-tocopherol (OR = 0.59, 95% CI = 0.37-0.94, P(trend) = 0.022). For all analytes, no heterogeneity of risk estimates or significant associations were observed by anatomical subsite. In the diffuse histological subtype, an inverse association was observed with the highest vs lowest quartile of lipid-unadjusted alpha-tocopherol (OR = 0.26, 95% CI = 0.11-0.65, P(trend) = 0.003). These results show that higher plasma concentrations of some carotenoids, retinol and alpha-tocopherol are associated with reduced risk of GC.     

Prospective study of carotenoids, tocopherols, and retinoid concentrations and the risk of breast cancer.

Previous prospective studies have raised the possibility that the antioxidantproperties of carotenoids and vitamin E (alpha-tocopherol) and the role of vitamin A (retinol) in cellular differentiation may be associated with a reduced risk of subsequent breast cancer. To investigate the association between serum and plasma concentrations of retinol, retinyl palmitate, alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, lycopene, total-carotenoids, alpha-tocopherol, and gamma-tocopherol with subsequent development of breast cancer, a nested case control study was conducted among female residents of Washington County, Maryland, who had donated blood for a serum bank in 1974 or 1989. Cases (n = 295) and controls (n = 295) were matched on age, race, menopausal status, and date of blood donation, and the analyses were stratified by cohort participation. Median concentrations of beta-carotene, lycopene, and total carotene were significantly lower in cases compared with controls in the 1974 cohort (13.1, 12.5, and 7.9% difference; P = 0.01, 0.04, and 0.04, respectively) and for lutein in the 1989 cohort (6.7% difference; P = 0.02). The risk of developing breast cancer in the highest fifth was approximately half of that of women in the lowest fifth for beta-carotene [odds ratio (OR) = 0.41; 95% confidence interval (CI) 0.22-0.79; P trend = 0.007], lycopene (OR = 0.55; 95% CI 0.29-1.06; P trend = 0.04), and total carotene (OR = 0.55; 95% CI 0.29-1.03; P trend = 0.02) in the 1974 cohort. There was generally a protective association for other micronutrients in both cohorts, although none reached statistical significance. The results suggest that carotenoids may protect against the development of breast cancer.     

The association between lung and prostate cancer risk, and serum micronutrients: results and lessons learned from beta-carotene and retinol efficacy trial.

beta-Carotene and Retinol Efficacy Trial is a nationwide chemoprevention trial that recruited 18,314 high-risk individuals to test the effect of supplemental beta-carotene and retinol on lung cancer incidence. In this report, we conducted a prospective nested case-control study of the association between serum carotenoids, retinoids, and tocopherols on both lung and prostate cancer incidence. Prerandomization serum samples were selected from 278 lung cancer cases and 205 prostate cancer cases, and 483 controls matched by high-risk population, study center location, age, sex (lung cancer only), smoking status, and year of randomization. Carotenoids, retinoids, and tocopherols were analyzed by high-performance liquid chromatography. Endpoints were confirmed by pathology review (lung cancer) or review of the pathology report (prostate cancer). In the control-only population, there was a significant association between tobacco use and serum micronutrient concentration. Current smokers compared with former smokers had lower mean levels of all of the micronutrients tested with zeaxanthin, beta-cryptoxanthin, alpha-carotene, alpha-tocopherol, retinol, and retinyl palmitate reaching statistical significance at P = 0.05. In the overall population, the mean serum concentrations of all of the micronutrients except gamma-tocopherol were lower for lung cancer cases than controls. Statistically significant trends across quartiles were observed in lutein (P = 0.02), zeaxanthin (P = 0.02), and alpha-tocopherol (P = 0.03). The carotenoid findings in the overall population were because of the strong inverse association between serum micronutrients and lung cancer in females. Statistically significant odds ratios (ORs) comparing 4(th) to 1st quartiles in the female population were seen in lutein [OR, 0.31; confidence interval (CI), 0.13-0.75], zeaxanthin (OR, 0.31; CI, 0.12-0.77), and beta-cryptoxanthin (OR, 0.34; CI, 0.14-0.81). For prostate cancer, mean serum concentrations were lower in cases for all of the nutrients except alpha-carotene. Only for alpha-tocopherol (P(trend) = 0.04) were the findings statistically significant. There was no statistically significant association between serum carotenoids and prostate cancer. Our findings provide additional support for the association between physiological levels of dietary micronutrients and cancer incidence.     

Nutritional and lifestyle determinants of DNA oxidative damage: a study in a Mediterranean population

In order to evaluate dietary and lifestyle determinants of oxidative DNA damage we used a modification of the 'comet assay' (single cell alkaline gel electrophoresis), with the fpg enzyme (formamidopyrimidine DNA glycosilase), to measure the basal level of DNA oxidation in peripheral lymphocytes donated by 71 healthy adults living in Florence, Italy. Detailed information about dietary and lifestyle habits was collected by two validated and standardized questionnaires; we also measured plasma concentrations of selected micro-nutrients (six carotenoids, retinol, alpha- and gamma-tocopherol). DNA damage, measured as percent DNA migrated in the comet tail (mean 4.67%, interquartile range 2.36-6.62%), was not associated with gender, age, weight, body mass index, physical activity or smoking history. A positive correlation with height and period of blood sampling emerged: DNA damage tended to be higher among taller subjects (P = 0.02) and in samples obtained in summer months (P = 0.02). Multivariate analyses showed a positive association with coffee (P = 0.01) and tomato consumption (P = 0.05). Instead, the consumption of cruciferous vegetables tended to be negatively associated with oxidative damage (P = 0.09). Furthermore, a positive non-significant association between the consumption of total vegetables and fresh fruit and DNA damage emerged (P = 0.08 and P = 0.10, respectively). The estimated intake of simple sugars showed a strong positive association with oxidative DNA damage (P = 0.01), while vitamin E showed a borderline positive association (P = 0.06). The plasma levels of several micro-nutrients did not appear to influence DNA damage. Our results, although based on a relatively small group of subjects, indicate that individual dietary and lifestyle habits only modestly affect the levels of lymphocyte DNA oxidation and suggest that specific dietary patterns, rich in fresh fruit and vegetables, are not clearly related to decreased oxidative damage in peripheral lymphocytes in a Mediterranean population.     

Effects of breast cancer treatments on plasma nutrient levels: implications for epidemiological studies.

The interpretation of case-control studies in which blood nutrient levels are examined as etiological factors in cancer is complicated by the possibility that either the disease or its treatment may alter these levels. Circulating levels of selected nutrients were examined prior to diagnostic biopsy and compared with levels 3 to 4 months after diagnosis among 71 women with breast cancer and 95 women with benign breast disease. Among women with benign breast disease or women with breast cancer who were not given postsurgical adjuvant drug therapy, levels of alpha-carotene, lycopene, alpha-tocopherol, cholesterol, and triglycerides did not change over time. In contrast, women who received chemotherapy had increased levels of cholesterol, retinol, and alpha- and gamma-tocopherol, and women on antiestrogen therapy showed increased levels of triglycerides and alpha-tocopherol. Overall, the concentrations of carotenoids (lycopene, alpha-carotene, and beta-carotene) did not change in breast cancer cases, although subgroup analyses showed increased levels of beta-carotene among cases not receiving drug treatment and decreased levels among those receiving antiestrogens. In summary, blood levels of some nutrients did not appear to be affected by breast cancer or its treatments, but changes were noted for levels of plasma lipids, tocopherols, retinol, and beta-carotene. Those investigating the etiological relationship between breast cancer and circulating nutrients need to consider these effects in designing and interpreting epidemiological studies.     

The impact of glutathione s-transferase M1 and cytochrome P450 1A1 genotypes on white-blood-cell polycyclic aromatic hydrocarbon-dna adduct levels in humans

Carcinogenic polycyclic aromatic hydrocarbons(a) form DNA adducts via a complex metabolic activation pathway that includes cytochrome P450(a) 1A1, whereas intermediate metabolites can be detoxified by conjugation through pathways including glutathione s-transferase M1 (GSTM1). PAH-DNA adducts can be measured in peripheral white blood cells (a) and should reflect the net effect of competing activation and detoxification pathways and ONA repair as well as exposure. We have previously shown that WBC PAH-DNA adducts measured by an enzyme-linked immunosorbent assay (a) were associated with recent, frequent consumption of charbroiled food among 47 nonsmoking wildland fire-fighters who provided two blood samples 8 wk apart. In the investigation reported here, which was performed in the same population, we measured the association between the GSTM1 null genotype, which results in loss of enzyme activity, and PAH-DNA adduct levels, hypothesizing that subjects with this genotype would have higher levels of DNA adducts because of their decreased ability to detoxify PAH metabolites. However, PAH-DNA adduct levels were nonsignificantly lower in subjects with the GSTM1 null genotype (n = 28) compared with other subjects (n=19) (median 0.04 fmol/μg DNA vs 0.07 fmol/μg DNA, respectively, P = 0.45, Wilcoxon rank-sum test). Adduct levels were also lower in the nine subjects heterozygous or homozygous for the CYP1A1 exon 7 polymorphism (which codes for a valine rather than isoleucine and is thought to be associated with greater CYP1A1 activity) compared with the 38 wild-type subjects (P = 0.12). In the entire group, there was a positive association between consuming charbroiled food and PAH-DNA adduct formation (r = 0.24, P = 0.02, Spearman rank-order correlation). This association was weaker in the subgroup of subjects with the GSTM1 null genotype (r = 0.03, P = 0.84) and stronger among the remaining subjects (r = 0.57, P = 0.0002). These results suggest that the GSTM1 null genotype and CYPT1A1 exon 7 polymorphism are not associated with increased susceptibility for PAH-DNA adduct formation in peripheral WBCs measured by ELISA in nonsmoking populations.© 1995 Wiley-Liss, Inc     

Prediagnostic levels of serum beta-cryptoxanthin and retinol predict smoking-related lung cancer risk in Shanghai, China.

Higher blood levels of beta-carotene have been found to be associated with reduced risk of lung cancer, but large intervention trials have failed to demonstrate reduced lung cancer incidence after prolonged high-dose beta-carotene supplementation. Data on blood levels of specific carotenoids other than beta-carotene in relation to lung cancer are scarce. Little is known about the relationship between prediagnostic serum levels of carotenoids, retinol, and tocopherols, and risk of lung cancer especially in non-Western populations. Between January 1986 and September 1989, 18,244 men ages 45-64 years participated in a prospective study of diet and cancer in Shanghai, China. Information on tobacco smoking and other lifestyle factors was obtained through in-person interviews. A serum sample was collected from each study participant at baseline. During the first 12 years of follow-up, 209 lung cancer cases, excluding those diagnosed within 2 years of enrollment, were identified. For each cancer case, three cancer-free control subjects were randomly selected from the cohort and matched to the index case by age (within 2 years), month and year of blood sample collection, and neighborhood of residence. Serum concentrations of retinol, alpha- and gamma-tocopherols, and specific carotenoids including alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, and lutein/zeaxanthin were determined on the 209 cases and 622 matched controls by high-performance liquid chromatography methods. A high prediagnostic serum level of beta-cryptoxanthin was significantly associated with reduced risk of lung cancer; relative to the lowest quartile, the smoking-adjusted relative risks (95% confidence intervals) for the 2nd, 3rd, and 4th quartile categories were 0.72 (0.41-1.26), 0.42 (0.21-0.84), and 0.45 (0.22-0.92), respectively (P for trend = 0.02). Increased serum levels of other specific carotenoids including alpha-carotene, beta-carotene, lycopene, and lutein/zeaxanthin were related to reduced risk of lung cancer although the inverse associations were no longer statistically significant after adjustment for smoking. A statistically significant 37% reduction in risk of lung cancer was noted in smokers with above versus below median level of total carotenoids. Serum retinol levels showed a threshold effect on lung cancer risk. Compared with the lowest quartile (<40 microg/dl), the smoking-adjusted relative risk (95% confidence interval) was 0.60 (0.39-0.92) for men in the 2nd-4th quartiles of retinol values combined; no additional decrease in risk was observed between individuals from the 2nd to 4th quartiles. There were no associations between prediagnostic serum levels of alpha- and gamma-tocopherols and lung cancer (all Ps for trend > or =0.4). The present data indicate that higher prediagnostic serum levels of total carotenoids and beta-cryptoxanthin were associated with lower smoking-related lung cancer risk in middle-aged and older men in Shanghai, China. Low level of serum retinol (with a threshold effect) is associated with increased lung cancer risk in this oriental population.     

Exposure to environmental tobacco smoke is associated with lower plasma beta-carotene levels among nonsmoking women married to a smoker.

We evaluated the association between exposure to environmental tobacco smoke (ETS) from husbands who smoke and plasma levels of antioxidant vitamins among nonsmoking women. A total of 1249 women from four areas in Italy answered a self-administered questionnaire, reported their diets on a food frequency questionnaire, had a medical examination, and gave their blood for alpha and beta-carotene, retinol, L-ascorbic acid, alpha-tocopherol, and lycopene determinations. Urinary cotinine was used to evaluate the level of recent exposure to ETS. After adjusting for study center, age and education, we found no association between ETS exposure and daily nutrient intake of beta-carotene, retinol, L-ascorbic acid, and alpha-tocopherol. However, we found an inverse dose-response relationship between intensity of current husband's smoke and concentrations of plasma beta-carotene and L-ascorbic acid. The associations remained even after controlling for daily beta-carotene and vitamin C intake and for other potential confounders (vitamin supplementation, alcohol consumption, and body mass index). Moreover, when urinary cotinine was considered as the exposure variable, a significant inverse association with plasma beta-carotene was found. The findings may be of interest to explain the biological mechanism that link ETS exposure with lung cancer and ischemic heart diseases.     

Plasma carotenoid, alpha-tocopherol and retinol concentrations and risk of colorectal adenomas: A case-control study in Japan

To investigate associations between plasma carotenoids, alpha-tocopherol and retinol with colorectal adenomas risk, we measured concentrations in 224 asymptomatic colorectal adenoma cases and 230 population-based controls matched for age and sex. After adjustment for age, history of colorectal adenomas and cancers, BMI, smoking, drinking status, multivitamin consumption and plasma total cholesterol, the risk of colorectal adenomas in the highest quartile was approximately half of that of men in the lowest quartile for alpha-carotene (OR=0.38; 95% CI: 0.18-0.84; P(trend)=0.01), beta-carotene (OR=0.51; 95% CI: 0.24-1.07; P(trend)=0.03) and total carotenoids (OR=0.48; 95% CI: 0.22-1.03; P(trend)=0.04). In addition, a protective association for alpha-carotene in women was also indicated, but which did not reach statistical significance (OR=0.53; 95% CI: 0.19-1.52; P(trend)=0.35). Our findings suggest a protective effect of carotenoids against the development of colorectal adenomas.     

Plasma micronutrient antioxidant in cancer patients.

The distribution of breast, colon, gastric, thyroid, oral, rectal, pancreatic and renal cancers were determined in 71 Kuwaitis, 45 other Arabs, and 26 Indians. Plasma levels of micronutrient antioxidants, retinol, alpha-tocopherol, lycopene, and beta-carotene were measured in the groups and in 90 matched controls for comparison. Cholesterol was measured to determine its association with the micronutrient antioxidants. Pancreatic cancer occurred exclusively in Kuwaitis, while breast and colon cancers were disproportionately higher in Kuwaitis than in the other groups. Micronutrient antioxidant levels were similar in the groups, except for higher lycopene levels in Kuwaitis. In most instances, the micronutrient antioxidants, except beta-carotene, decreased significantly in levels in patients than in controls. Low levels of retinol, lycopene, and beta-carotene were strongly associated with pancreatic cancer. Compared to controls, significantly increased levels of beta-carotene occurred in breast, colon, thyroid, and renal cancers; increased lycopene occurred in oral cancer, and increased alpha-tocopherol occurred in pancreatic cancer. Alpha-tocopherol strongly correlated with cholesterol. Generally, changes in alpha-tocopherol/ cholesterol ratios mimicked those of alpha-tocopherol levels. Micronutrient antioxidant levels were significantly lower in male patients than female patients. Age showed a negative but statistically insignificant relationship with micronutrient antioxidants. Lycopene strongly correlated with alpha-carotene and alpha-tocopherol with retinol. Among the patients, all micronutrient antioxidants except retinol decreased significantly in levels in smokers than nonsmokers, suggesting susceptibility to cigarette smoke oxidative stress. We conclude that micronutrient antioxidant depletions and altered associations may imply tumor utilization or antioxidant burden in oxidative stress or both. Furthermore, the incidence of pancreatic, colon and breast cancers among Kuwaitis warrants further study.     

Association between alpha-tocopherol, gamma-tocopherol, selenium, and subsequent prostate cancer

BACKGROUND: Selenium and alpha-tocopherol, the major form of vitamin E in supplements, appear to have a protective effect against prostate cancer. However, little attention has been paid to the possible role of gamma-tocopherol, a major component of vitamin E in the U.S. diet and the second most common tocopherol in human serum. A nested case-control study was conducted to examine the associations of alpha-tocopherol, gamma-tocopherol, and selenium with incident prostate cancer. METHODS: In 1989, a total of 10,456 male residents of Washington County, MD, donated blood for a specimen bank. A total of 117 of 145 men who developed prostate cancer and 233 matched control subjects had toenail and plasma samples available for assays of selenium, alpha-tocopherol, and gamma-tocopherol. The association between the micronutrient concentrations and the development of prostate cancer was assessed by conditional logistic regression analysis. All statistical tests were two-sided. RESULTS: The risk of prostate cancer declined, but not linearly, with increasing concentrations of alpha-tocopherol (odds ratio (highest versus lowest fifth) = 0.65; 95% confidence interval = 0.32--1.32; P(trend) =.28). For gamma-tocopherol, men in the highest fifth of the distribution had a fivefold reduction in the risk of developing prostate cancer than men in the lowest fifth (P:(trend) =.002). The association between selenium and prostate cancer risk was in the protective direction with individuals in the top four fifths of the distribution having a reduced risk of prostate cancer compared with individuals in the bottom fifth (P(trend) =.27). Statistically significant protective associations for high levels of selenium and alpha-tocopherol were observed only when gamma-tocopherol concentrations were high. CONCLUSIONS: The use of combined alpha- and gamma- tocopherol supplements should be considered in upcoming prostate cancer prevention trials, given the observed interaction between alpha-tocopherol, gamma-tocopherol, and selenium.     

Plasma concentrations of coenzyme Q10 and tocopherols in cervical intraepithelial neoplasia and cervical cancer.

Cervical intraepithelial neoplasia (CIN) may, at times, unpredictably progress to invasive carcinoma of the cervix. Epidemiological nutritional studies suggest that higher dietary consumption and circulating levels of certain micronutrients may be protective against cervical cancer. However, a preventive role of dietary antioxidants in CIN is not well established. The purpose of this cross-sectional study was to investigate the comparative plasma concentrations of three potent antioxidants, coenzyme Q(10,) alpha-tocopherol and gamma-tocopherol, in women with normal Pap smears and patients with a biopsy-confirmed histopathological lesion diagnosed as CIN or cervical cancer. Plasma concentrations of coenzyme Q(10,) alpha-tocopherol and gamma-tocopherol were measured by high-pressure liquid chromatography in both normal women without any history of abnormal Pap smears (n=48), and patients with histopathologically confirmed diagnoses of: (a) CIN I, n=98; (b) CIN II, n=49; (c) CIN III, n=10; and (d) cervical cancer, n=25. The mean plasma levels of coenzyme Q(10), alpha-tocopherol and gamma-tocopherol were significantly lower (P<0.001,<0.001, and<0.001, respectively by Kruskal-Wallis test) in patients with various grades of CIN and cervical cancer compared with controls. After controlling for age and smoking, an inverse association between histological grades of epithelial lesions and both plasma coenzyme Q(10) and alpha-tocopherol concentrations was observed. The low plasma concentrations of coenzyme Q(10) may be due to deficient dietary intake or a decrease in endogenous coenzyme Q(10) biosynthesis that may reflect increased utilization as a result of free radical reactive oxygen species induced oxidative stress. Further molecular studies on the mechanistic role of antioxidants in women with precancer cervical lesions are needed.     

A prospective study of XRCC1 haplotypes and their interaction with plasma carotenoids on breast cancer risk

The XRCC1 protein is involved in the base excision repair pathway through interactions with other proteins. Polymorphisms in the XRCC1 gene may lead to variation in repair proficiency and confer inherited predisposition to cancer. We prospectively assessed the associations between polymorphisms and haplotypes in XRCC1 and breast cancer risk in a nested case-control study within the Nurses' Health Study (incident cases, n = 1004; controls, n = 1385). We further investigated gene-environment interactions between the XRCC1 variations and plasma carotenoids on breast cancer risk. We genotyped four haplotype-tagging single nucleotide polymorphisms (Arg(194)Trp, C26602T, Arg(399)Gln, and Gln(632)Gln) in the XRCC1 gene. Five common haplotypes accounted for 99% of the chromosomes in the present study population of mostly Caucasian women. We observed a marginally significant reduction in the risk of breast cancer among (194)Trp carriers. As compared with no-carriers, women with at least one (194)Trp allele had a multivariate odds ratio of 0.79 (95% of the confidence interval, 0.60-1.04). The inferred haplotype harboring the (194)Trp allele was more common in controls than in cases (6.6 versus 5.3%, P = 0.07). We observed that the Arg(194)Trp modified the inverse associations of plasma alpha-carotene level (P, ordinal test for interaction = 0.02) and plasma beta-carotene level (P, ordinal test for interaction = 0.003) with breast cancer risk. No suggestion of an interaction was observed between the Arg(194)Trp and cigarette smoking. Our results suggest an inverse association between XRCC1 (194)Trp allele and breast cancer risk. The findings of the effect modification of the Arg(194)Trp on the relations of plasma alpha- and beta-carotene levels with breast cancer risk suggest a potential protective effect of carotenoids in breast carcinogenesis by preventing oxidative DNA damage.     

Modification effects of GSTM1, GSTT1 and CYP2E1 polymorphisms on associations between raw salted food and incomplete intestinal metaplasia in a high-risk area of stomach cancer

Incomplete intestinal metaplasia (IM) is a precursor of stomach cancer. To identify risk factors of incomplete IM, a 2-stage survey was carried out in 1995 among 1,485 residents in Matzu, an area with highest mortality from stomach cancer in Taiwan. There were 312 study subjects including 174 men and 138 women sampled for the gastroendoscopic examination of IM. Information on personal and familial history of stomach cancer, cigarette smoking, alcohol consumption and intake frequency of various salted food items were obtained by personal interview based on a structured questionnaire. Blood samples were collected from each participant. Four biopsies per subject were taken from all subjects at gastroendoscopic examination to diagnose the status of IM pathologically. The Helicobacter pylori in biopsies was detected by the histomorphological or immunochemistry method, and antibodies against H. pylori in serum by the enzyme-linked immunosorbent assay. Plasma level of selenium was determined by atomic absorption spectrometry, plasma level of retinol, alpha-tocopherol, alpha-carotene, and beta-carotene by high performance liquid chromatography, genotypes of glutathione S-transferase (GST) M1 and T1 and cytochrome P450 (CYP) 2E1 by polymerase chain reaction. The significant association between history of stomach cancer among first-degree relatives and incomplete IM was found (odds ratio [OR] = 2.50; 95% confidence interval [CI] = 1.15-5.43). There was no association between H. pylori infection and incomplete IM. Alcohol drinkers for >20 years had an elevated risk compared to non-drinkers (OR = 3.34; 95% CI = 1.19-9.39). No associations between incomplete IM and plasma levels of selenium, retinol, alpha-tocopherol, alpha-carotene and beta-carotene were found. Salted food including salted meat, dehydrated salted vegetables and raw salted seafood consumed at ages of 相似文献   

Prospective study of serum vitamin E levels and esophageal and gastric cancers

Participants in the General Population Trial, a randomized nutrition intervention trial in Linxian, China, who received a combination of selenium, beta-carotene, and vitamin E supplements, had statistically significantly lower cancer mortality rates than those who did not receive the supplements. In the current study, we used a case-cohort design to examine the association between pre-trial serum vitamin E levels and the risks of developing esophageal and gastric cancers during the trial. We measured serum alpha- and gamma-tocopherol and cholesterol levels in 1072 case patients with incident esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), or gastric noncardia cancer (GNCC) and in 1053 control subjects. The relative risks for comparisons of the highest to the lowest quartiles of serum alpha-tocopherol were 0.63 (95% confidence interval [CI] = 0.44 to 0.91) for ESCC, 0.84 (95% CI = 0.55 to 1.26) for GCC, and 2.05 (95% CI = 0.89 to 4.75) for GNCC. Serum gamma-tocopherol level was not associated with the incidence of any of these cancers. Our findings provide support for the role of alpha-tocopherol in the etiology of upper gastrointestinal cancers.