Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0242379 (lung cancer)
71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:The association between lung and prostate cancer risk, and serum micronutrients: results and lessons learned from beta-carotene and retinol efficacy trial. 1281 97

There is a growing body of interest on the role of beta-carotene and other carotenoids in human chronic diseases, including cancer. While epidemiological evidence shows that people who ingest more dietary carotenoids exhibit a reduced risk for cancer, results from intervention trials indicate that supplemental beta-carotene enhances lung cancer incidence and mortality among smokers. A possible mechanism which can explain the dual role of beta-carotene as both a beneficial and a harmful agent in cancer as well as in other chronic diseases is its ability in modulating intracellular redox status. beta-Carotene may serve as an antioxidant or as a prooxidant, depending on its intrinsic properties as well as on the redox potential of the biological environment in which it acts. This review summarizes the available evidence for a prooxidant activity of beta-carotene in cultured cells, focusing on biochemical and molecular markers of oxidative stress, which have been reported to be enhanced by the carotenoid.
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PMID:Prooxidant effects of beta-carotene in cultured cells. 1458 6

Intervention trials with supplemental beta-carotene have observed either no effect or a harmful effect on lung cancer risk. Because food composition databases for specific carotenoids have only become available recently, epidemiological evidence relating usual dietary levels of these carotenoids with lung cancer risk is limited. We analyzed the association between lung cancer risk and intakes of specific carotenoids using the primary data from seven cohort studies in North America and Europe. Carotenoid intakes were estimated from dietary questionnaires administered at baseline in each study. We calculated study-specific multivariate relative risks (RRs) and combined these using a random-effects model. The multivariate models included smoking history and other potential risk factors. During follow-up of up to 7-16 years across studies, 3,155 incident lung cancer cases were diagnosed among 399,765 participants. beta-Carotene intake was not associated with lung cancer risk (pooled multivariate RR = 0.98; 95% confidence interval, 0.87-1.11; highest versus lowest quintile). The RRs for alpha-carotene, lutein/zeaxanthin, and lycopene were also close to unity. beta-Cryptoxanthin intake was inversely associated with lung cancer risk (RR = 0.76; 95% confidence interval, 0.67-0.86; highest versus lowest quintile). These results did not change after adjustment for intakes of vitamin C (with or without supplements), folate (with or without supplements), and other carotenoids and multivitamin use. The associations generally were similar among never, past, or current smokers and by histological type. Although smoking is the strongest risk factor for lung cancer, greater intake of foods high in beta-cryptoxanthin, such as citrus fruit, may modestly lower the risk.
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PMID:Dietary carotenoids and risk of lung cancer in a pooled analysis of seven cohort studies. 1474 31

Pharmacologic or nutritional prevention of lung cancers is needed, especially for 60 million Americans who are former smokers. A portfolio of large-scale trials of beta-carotene, beta-carotene with and without vitamin E, and beta-carotene plus vitamin A demonstrated no benefit whatsoever from beta-carotene. The alpha-Tocopherol/beta-Carotene Trial and the beta-Carotene and Retinol Efficacy Trial found significant increases in lung cancer risk and total mortality. Laboratory research soon identified multiple adverse molecular effects. Nevertheless, chemoprevention remains an active, promising strategy, with new hypotheses and new candidate agents, including many already approved as therapies. The most active area currently is focused on selective inhibition of arachidonic metabolism, both Cox-2 and Lox pathways.
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PMID:Human lung cancer chemoprevention strategies: Parker B. Francis lecture. 1513 59

Supplemental beta-carotene has been shown to increase lung cancer risk in recent chemoprevention trials, especially in current smokers. Several possible mechanisms for this effect have been suggested based upon in vitro and animal studies, but mechanistic data from human studies to explain the excess risk are lacking. beta-Carotene has both antioxidant and prooxidant effects in vitro; therefore, we evaluated whether or not high-dose supplemental beta-carotene might have prooxidant effects in vivo, especially in current smokers taking high-dose supplemental beta-carotene for several years (median 4.0 yr). Urine samples (n = 55 total) were collected from both smokers and nonsmokers participating in a multiyear randomized chemoprevention trial of supplemental beta-carotene (50 mg/day) versus placebo. Samples were analyzed by GC/MS for total isoprostanes and for 8-iso-prostaglandin F2 (8-iso-PGF2), stable end products of lipid peroxidation in vivo. Smokers had higher levels of both total isoprostanes and 8-iso-PGF2. Smokers and nonsmokers randomized to beta-carotene had nonsignificantly lower concentrations of total isoprostanes and of 8-iso-PGF2 [mean +- SD 8-iso-PGF2/ml = 2.00 +- 1.72 (placebo smoker); 1.72 +- 1.66 (beta-carotene smoker); 1.22 +- 0.68 (placebo nonsmoker); 0.97 +- 0.62 (beta-carotene nonsmoker)]. These results indicate that supplemental beta-carotene, even when given at high doses for many years, does not have prooxidant effects in either smokers or nonsmokers, as measured by urinary excretion of F2-isoprostanes.
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PMID:Supplemental beta-carotene, smoking, and urinary F2-isoprostane excretion in patients with prior early stage head and neck cancer. 1545 52

Increased physical activity has been associated with a reduction in the incidence and mortality from all-site cancer and some site-specific cancers in samples of primarily nonsmoking individuals; however, little is known about whether physical activity is associated with similar risk reductions among smokers and ex-smokers. This study examined physical activity in relation to all-site cancer and lung cancer incidence and mortality in a sample of current and former smokers (n = 7,045; 59% male; 95% Caucasian; mean age, 63 years) drawn from the beta-Carotene and Retinol Efficacy Trial, a lung cancer chemoprevention trial. Hazard rate ratios and 95% confidence intervals associated with a 1 SD increase in physical activity were 0.86 (0.80-0.94) for all-site cancer only among men, 0.84 (0.69-1.03) for lung cancer only for younger participants, 0.75 (0.59-0.94) for cancer mortality among younger participants and 0.68 (0.53-0.89) among women, and 0.69 (0.53-0.90) for lung cancer mortality only among women. These results suggest that incidence may be more attenuated by physical activity for men and mortality more attenuated for women. Effects may be more pronounced for younger people and may differ inconsistently by pack-years of smoking. Physical activity may play a role in reducing cancer risk and mortality among those with significant tobacco exposure. Prospective studies using more sophisticated measures of physical activity assessed at multiple time points during follow-up are needed to corroborate these associations.
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PMID:Physical activity in relation to all-site and lung cancer incidence and mortality in current and former smokers. 1559 85

Despite numerous published studies, debate continues regarding the risk of developing lung cancer among men exposed occupationally to asbestos, particularly those without radiographic or functional evidence of asbestosis. The beta-Carotene and Retinol Efficacy Trial (CARET), a study of vitamin supplementation for chemoprevention of lung cancer, has followed 4,060 heavily exposed US men for 9-17 years. Lung cancer incidence for 1989-2002 was analyzed using a stratified proportional hazards model. The study confirmed excessive rates of lung cancer among men with radiographic asbestosis. Comparison of study arms revealed a strong, unanticipated synergy between radiographic profusion category and the active intervention. In the large subgroup of men with normal lung parenchyma on chest radiograph at baseline, there was evidence of exposure-related lung cancer risk: Men with more than 40 years' exposure in high-risk trades had a risk approximately fivefold higher than men with 5-10 years, after adjustment for covariates. The effect in these men was independent of study intervention arm, but pleural plaques on the baseline radiograph and abnormal baseline flow rate were strong independent predictors of subsequent lung cancer. Residual confounding by subclinical asbestosis, exposure to unmeasured lung carcinogens, or differences in smoking are unlikely to explain these observations better than a carcinogenic effect of asbestos per se.
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PMID:Predictors of lung cancer among asbestos-exposed men in the {beta}-carotene and retinol efficacy trial. 1567 Dec 58

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.
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PMID:Carotenoid actions and their relation to health and disease. 1630 38

Results from some intervention trials indicated that supplemental beta-carotene enhanced lung cancer incidence and mortality in chronic smokers. The aim of this study was to verify the hypothesis that high concentrations of the carotenoid, under the pO2 present in lung (100-150 mmHg), may exert deleterious effects through a prooxidant mechanism. To test this hypothesis, we examined the interactions of beta-carotene and cigarette smoke condensate (tar) on the formation of lipid peroxidation products in rat lung microsomal membranes enriched in vitro with varying beta-carotene concentrations (from 1 to 10 nmol/mg prot) and then incubated with tar (6-25 microg/ml) under different pO2. As markers of lipid peroxidation, we evaluated the levels of conjugated dienes and malondialdehyde, possessing mutagenic and pro-carcinogenic activity. The exposure of microsomal membranes to tar induced a dose-dependent enhancement of lipid peroxidation, which progressively increased as a function of pO2. Under a low pO2 (15 mmHg), beta-carotene acted clearly as an antioxidant, inhibiting tar-induced lipid peroxidation. However, the carotenoid progressively lost its antioxidant efficiency by increasing pO2 (50-100 mmHg) and acted as a prooxidant at pO2 ranging from 100 to 760 mmHg in a dose-dependent manner. Consistent with this finding, the addition of alpha-tocopherol (25 microM) prevented the prooxidant effects of the carotenoid. beta-Carotene auto-oxidation, measured as formation of 5,6-epoxy-beta,beta-carotene, was faster at high than at low pO2 and the carotenoid was more rapidly consumed in the presence of tar. These data point out that the carotenoid may enhance cigarette smoke-induced oxidative stress and exert potential deleterious effects at the pO2 normally present in lung tissue.
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PMID:Dual role of beta-carotene in combination with cigarette smoke aqueous extract on the formation of mutagenic lipid peroxidation products in lung membranes: dependence on pO2. 1670 89

A number of epidemiological studies have reported associations of beta-carotene plasma levels or intake with decreased lung cancer risk. However, intervention studies in smokers reported increased lung tumor rates after high long-term beta-carotene supplementation. For insight into these conflicting results, we studied the influence of beta-carotene on tobacco smoke carcinogen-induced lung cancer development in the A/J-mouse using 4-(N-Methyl-N-nitro samino)-1-(3-pyridyl)-1-butanone (NNK) as the initiator and lung adenoma multiplicity as the functional endpoint. Gene regulation of the putative tumor suppressor RARbeta in mouse lung was analyzed by quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for its relevance in predicting the endpoint of lung cancer. A/J-mice achieved plasma beta-carotene levels of up to 3 micromol/L within 4 wk and up to 6 micromol/L after 6 mo of supplementation on a diet modified to enhance beta-carotene absorption. Despite high lung beta-carotene concentrations of up to 6 micromol/kg, tumor multiplicity was not significantly affected by the beta-carotene treatment, either in carcinogen-initiated or non-initiated mice, and was unrelated to beta-carotene dose and the time point of treatment during cancer formation. Tumor multiplicity did not correlate with beta-carotene plasma levels in NNK-treated animals. All RARbeta isoforms were significantly suppressed in the lungs of NNK- and NNK plus high dose beta-carotene-treated animals. However, the number of tumors per mouse did not correlate with the RARbeta-isoform expression levels. beta-carotene alone after 3 mo of supplementation mildly but significantly increased levels of RARbeta1, beta2, and beta4. This increase persisted for 6 mo for RARbeta2 and beta4. In summary, we found no effect of beta-carotene on tumor formation in the NNK-initiated A/J-mouse lung cancer model with respect to dose or time point of treatment. beta-Carotene-induced changes in RARbeta isoform gene expression levels were not predictive for the number of lung tumors but were indicative of intact beta-carotene metabolism and persistent sensitivity to retinoic acid in the mice. Down-regulation of RARbeta in NNK-induced adenoma-bearing lungs was similar to that observed in human lung cancer and further confirms the A/J-mouse as a valuable model for lung carcinogenesis.
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PMID:beta-carotene-induced changes in RARbeta isoform mRNA expression patterns do not influence lung adenoma multiplicity in the NNK-initiated A/J mouse model. 1689 70


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