Diet and cancer prevention

Dietary lipids and endometrial cancer: the current epidemiologic evidence

BACKGROUND

Because dietary fat has been postulated to affect obesity and estrogen levels, two important risk factors for endometrial cancer, its association with this disease has received some attention. We summarize here the current evidence for several dietary lipids.

METHODS

Searches were conducted to identify peer-reviewed manuscripts up to December 2006. Two cohort studies and nine case-control studies were included in meta-analyses.

RESULTS

Random-effects summary estimates for case-control studies were 1.24 (95% CI: 1.10, 1.41) per 10% kcal from total fat and 1.28 (95% CI: 1.12, 1.47) per 10 g/1,000 kcal of saturated fat. The only cohort study evaluating total fat and saturated fat did not find an association. We estimated a 35% increased risk (95% CI: 0.96, 1.90) per 150 mg/1,000 kcal of cholesterol intake, based on six case-control studies. For animal fat (per 10 g/1,000 kcal) the summary estimates were 0.78 (95% CI: 0.63, 0.96) and 1.34 (95% CI: 1.06, 1.69) for two cohort and four case-control studies, respectively.

CONCLUSIONS

Case-control data suggest an increased risk for total, saturated, and animal fat. However, the limited available cohort data do not support these associations. Additional data, particularly from prospective studies, are needed before conclusions can be drawn.

A temporal association between folic acid fortification and an increase in colorectal cancer rates may be illuminating important biological principles: a hypothesis

Nationwide fortification of enriched uncooked cereal grains with folic acid began in the United States and Canada in 1996 and 1997, respectively, and became mandatory in 1998. The rationale was to reduce the number of births complicated by neural tube defects. Concurrently, the United States and Canada experienced abrupt reversals of the downward trend in colorectal cancer (CRC) incidence that the two countries had enjoyed in the preceding decade: absolute rates of CRC began to increase in 1996 (United States) and 1998 (Canada), peaked in 1998 (United States) and 2000 (Canada), and have continued to exceed the pre-1996/1997 trends by 4 to 6 additional cases per 100,000 individuals. In each country, the increase in CRC incidence from the prefortification trend falls significantly outside of the downward linear fit based on nonparametric 95% confidence intervals. The statistically significant increase in rates is also evident when the data for each country are analyzed separately for men and women. Changes in the rate of colorectal endoscopic procedures do not seem to account for this increase in CRC incidence. These observations alone do not prove causality but are consistent with the known effects of folate on existing neoplasms, as shown in both preclinical and clinical studies. We therefore hypothesize that the institution of folic acid fortification may have been wholly or partly responsible for the observed increase in CRC rates in the mid-1990s. Further work is needed to definitively establish the nature of this relationship. In the meantime, deliberations about the institution or enhancement of fortification programs should be undertaken with these considerations in mind.

The surgeon's role in cancer prevention. The model in colorectal carcinoma

Cancer Prevention is an emerging field, capturing the old traditional concept of anticipating the development of a major disease and preventing its full impact by early detection, treatment, or aborting the tumorigenic process by a "molecular vaccine" and alleviating the full impact of the disease. Surgeons are important clinician scientists who can carry this discipline forward and develop its full potential in the clinics and in the community. Advances in molecular biology, genetics, and other technologies have permitted seminal understanding of the carcinogenic pathways and identification of targets and intermediate end points in neoplasia. In this review, we will see that we have the means of preventing significant numbers of colorectal carcinomas (CRC).

Kaempferol induced inhibition of HL-60 cell growth results from a heterogeneous response, dominated by cell cycle alterations

Dietary flavonoids may be exploitable as chemotherapeutics and preventatives for critical health conditions, including cancer. Antiproliferative effects are commonly ascribed to such compounds but ambiguity exists as to the principal mechanism of action and the universal benefit of exposure, particularly at high concentrations. Here, we identify heterogeneous responses within HL-60 promyelocytic leukaemia cells that explain contradictions in the reported origin of the antiproliferative action of kaempferol, a dietary abundant flavonoid. At > or =10 microM, kaempferol exposure is predominantly characterised by cell cycle alterations, notably a significant increase in S-phase and a progressive accumulation in G2-M with 10 and > or =20 microM kaempferol, respectively. However, a limited but consistent membrane damage is observed across the 1-100 microM exposure and at 1 microM occurs devoid from indices of apoptosis which are only consistently observed with > or =10 microM kaempferol treatment. At the most cytotoxic exposures, multiparametric flow cytometric analysis revealed distinct sub populations of cells. Cells with decreased size, typical of apoptosis and necrosis, possessed heightened caspase-3 activity, decreased anti-apoptotic Bcl-2 expression and changes to membrane asymmetry and integrity. The remaining population had elevated active caspase-3 but no change or a moderate increase in Bcl-2 expression and no plasma membrane alterations. Differentiation was not a significant factor in HL-60 growth inhibition. In conclusion, kaempferol-induced growth inhibition is dominated by cell cycle changes but involves a limited cytotoxicity, which we propose results from a membrane damage centred as well as an apoptotic process. This heterogeneity of response may confound the disease-preventative role and pharmacological application of this flavonoid.

Photodegradation of 5-methyltetrahydrofolate: biophysical aspects

5-methyltetrahydrofolate (5MTHF) absorbs UV radiation and has an absorption coefficient of 24250+/-1170 M(-1) cm(-1) at 290 nm. It has a weak fluorescence emission in the wavelength region around 360 nm. Our data demonstrated induction of 5-methyldihydrofolate by exposure to UVB and, after continues irradiation, p-aminobenzoyl-L-glutamic acid was found. The photodegradation of 5MTHF follows a first order kinetic with a degradation rate constant of 9.2 x 10(-3) min(-1) under our conditions (fluence rate of 2.15 mW cm(-2), exposure wavelengths from 280 to 350 nm). Our results indicate that a direct degradation of 5MTHF by UV exposure in humans in vivo is rather unlikely. 5MTHF mainly absorbs, and is degraded by, UVB and UVC, radiation that does not penetrate the earth's atmosphere and the human skin well.

[Effects of kakisu (persimmon vinegar) on plasma antioxidant power and urinary 8-isoprostane level]

OBJECTIVES

To clarify the antioxidative effects of kakisu (persimmon vinegar), plasma antioxidant power and urinary oxidative stress level in healthy subjects were measured using enzyme immunological assays.

METHODS

Eighty-one subjects (age 30-69, 58.4 +/- 0.8) were randomly divided into two groups using a crossover design. Group A drank kakisu for 56 days starting in March, whereas group B drank kakisu for 54 days starting in June. Copper reducing equivalent level in plasma was measured as antioxidant power, and urinary 8-isoprostane (8-iso-prostaglandin F2alpha) level was measured as oxidative stress marker.

RESULTS

Baseline plasma antioxidant power and urinary 8-isoprostane level showed no significant correlation among the subjects in this study. By drinking kakisu for 8 weeks, total antioxidant power significantly increased, and urinary 8-isoprostane level decreased. Total antioxidant power increased more markedly in group A than in group B. In contrast, urinary oxidative stress level decreased more markedly in group B than in group A. Smoking habits significantly correlated with urinary 8-isoprostane level. Males were more sensitive to the antioxidative effects of kakisu than females.

CONCLUSIONS

Kakisu has antioxidative effects that increase plasma antioxidant power and reduce urinary 8-isoprostane level. Further study is needed to clarify the influence of season and gender on such antioxidative effects.

Silibinin inhibits constitutive activation of Stat3, and causes caspase activation and apoptotic death of human prostate carcinoma DU145 cells

Transcription factor signal transducer and activator of transcription (Stat)-3 is activated constitutively in prostate cancer (PCA) suggesting that its disruption could be an effective approach to control this malignancy. Here we assessed whether silibinin, a flavanone from Silybum marianum with proven anticancer efficacy in various cancer models, inhibits Stat3 activation in DU145 cells, and if it does, what is the biological fate of the cells? At 50 muM or higher concentrations for 24 or 48 h, silibinin concentration dependently reduced constitutive Stat3 phosphorylation at Tyr705 and Ser727 residues under both serum and serum-starved conditions. Constitutively active Stat3-DNA binding was also inhibited concentration dependently by silibinin; however, apoptotic death together with caspase and poly(ADP-ribose) polymerase (PARP) cleavage was observed by silibinin only under serum-starved conditions suggesting that additional survival pathways are active under serum conditions. In other studies, cells were treated with various specific pharmacological inhibitors where phosphorylation of Stat3 was not reduced by epidermal growth factor receptor and Mitogen activated protein/extracellular signal regulate kinase kinase (MEK1/2) inhibitors, suggesting lack of significant roles of these in Stat3 activation in DU145 cells. Janus kinase (JAK)-1 and JAK2 inhibitors strongly reduced Stat3 phosphorylation but did not result in apoptotic cell death. Interestingly, JAK1 inhibitor only in combination with silibinin resulted in a complete reduction in Stat3 phosphorylation at Tyr705, activated caspase-9 and caspase-3, and caused strong PARP cleavage and apoptotic death of DU145 cells. Given a critical role of Stat3 activation in PCA, our results showed that silibinin inhibits constitutively active Stat3 and induces apoptosis in DU145 cells, and thus might have potential significance in therapeutic intervention of this deadly malignancy.

Modulation of aflatoxin toxicity and biomarkers by lycopene in F344 rats

Modulation by lycopene of aflatoxin B(1) (AFB(1))-induced toxic effects, metabolism, and metabolic activations was studied in young F344 rats. Animals were pretreated orally with either corn oil (control group) or lycopene [100 mg/kg body weight (b.w.), intervention group] 5 days/week for 2 weeks. Control animals were then treated daily with AFB(1) (250 microg/kg b.w) alone. Intervention animals were administered lycopene (100 mg/kg b.w.) at 1 h following a daily treatment with AFB(1) (250 mug/kg b.w.). Pretreatment and intervention with lycopene significantly reduced the toxic effect caused by AFB(1) and greatly modulated AFB(1) metabolism and metabolic activation. Urinary excretion of AFB(1) phase 1 metabolites, AFM(1), AFQ(1), and AFP(1), was significantly decreased in lycopene-treated animals. Formation of serum AFB(1)-albumin adducts was also significantly reduced. The rate of reduction was from approximately 30% on day 1 (p<0.05) to 67.7% on day 15 (p<0.001). Lycopene intervention also significantly reduced formation of AFB(1)-DNA adducts in liver compared to control animals, with the highest reduction (52.7%) occurring on day 3 (p<0.05). Levels of AFB(1)-N(7)-guanine excreted in urine were also significantly decreased. Urinary excretion of the phase 2 detoxification metabolite, AFB(1)-mecapturic acid, was significantly increased in lycopene-intervened animals. AFB(1)-induced urinary excretion of 8-hydroxydeoxyguanosine was also reduced to 50% on day 7 after lycopene intervention. Collectively, these results suggest that inhibition of phase 1 metabolism and metabolic activation, as well as induction of phase 2 detoxification enzyme activity are the potential mechanisms for the chemopreventive effects of lycopene.

Relation of insulin-like growth factor (IGF) I and IGF-binding protein 3 concentrations with intakes of fruit, vegetables, and antioxidants

BACKGROUND

Fruit, vegetable, and antioxidant intakes may reduce the risk of several insulin-like growth factor (IGF)-related chronic diseases, such as certain types of cancers and cardiovascular diseases.

OBJECTIVE

This study investigated whether intakes of fruit, vegetables, and antioxidants (beta-carotene, lycopene, and vitamin C) are associated with plasma IGF-I and IGF-binding protein 3 (IGFBP-3) concentrations.

DESIGN

Plasma IGF-I and IGFBP-3 concentrations were measured in 1542 healthy women by enzyme-linked immunosorbent assay. A self-administered semiquantitative food-frequency questionnaire was used to estimate mean daily dietary intakes of fruit, vegetables, and antioxidants over the year preceding blood sampling. Multivariate analyses were performed by using generalized linear models to evaluate the association of quintiles of daily intakes with concentrations of growth factors.

RESULTS

A higher intake of citrus fruit was associated with higher concentrations of IGF-I (215 ng/mL for quintile 5 compared with 205 ng/mL for quintile 1; P for trend = 0.04) and with lower concentrations of IGFBP-3 (4803 ng/mL for quintile 5 compared with 4960 ng/mL for quintile 1; P for trend = 0.04). Higher dietary vitamin C intake was associated with higher concentrations of IGF-I (214 ng/mL for quintile 5 compared with 204 ng/mL for quintile 1; P for trend = 0.02) and lower concentrations of IGFBP-3 (4813 ng/mL for quintile 5 compared with 4953 ng/mL for quintile 1; P for trend = 0.03). Total intake of fruit and vegetables and intakes of other botanical fruit and vegetable subgroups, beta-carotene, and lycopene were not related to either IGF-I or IGFBP-3 concentrations.

CONCLUSION

Women with higher intakes of citrus fruit or dietary vitamin C tend to have higher plasma concentrations of IGF-I and lower plasma concentrations of IGFBP-3.

Effect of dietary antioxidants and risk of oral, pharyngeal and laryngeal squamous cell carcinoma according to smoking and drinking habits

Several intervention trials and prospective studies have reported that beta-carotene supplementation is not associated with a decreased risk of several cancers among smokers and drinkers, and that it may even have adverse effects in these groups. The relationship between dietary antioxidant intake and the risk of head and neck squamous cell carcinoma (HNSCC) has been examined intensively, but little is known about the effects of antioxidants on HNSCC with respect to smoking and drinking habits. Here, we conducted a case-control study of 385 histologically confirmed cases of HNSCC (193 oral, 132 pharyngeal and 60 laryngeal), excluding nasal and paranasal cancer, and 1925 age-matched and sex-matched cancer-free outpatient controls using data from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center, Japan. The intake of nutrients and food groups was assessed with a food frequency questionnaire, and multivariate-adjusted odds ratios for cancer were estimated for smoking and drinking habits using logistic models. The results showed an overall inverse association between the intake of dietary antioxidants, including carotene, and vitamins C and E, and risk of HNSCC. The protective effect of these antioxidants was seen in both men and women. High consumption of antioxidants was associated with a decreased risk of HNSCC among smokers, drinkers and those with both smoking and drinking habits. These findings suggest that dietary antioxidant intake prevents HNSCC in smokers and drinkers.

Rapid screening of ascorbic acid, glycoalkaloids, and phenolics in potato using high-performance liquid chromatography

Evaluation of phenolic metabolism in potato tubers (Solanum tuberosum) would be facilitated by faster analytical methods. A high-throughput HPLC method was developed for the qualitative and quantitative determination in potato of numerous phenolic compounds, the sum of the glycoalkaloids chaconine and solanine, plus ascorbic acid. Following a fast extraction, HPLC run times of 12 min were achieved with the use of a monolithic RP C18 column. UV and MS analyses were used to characterize the phenolic complement in extracts from two white-fleshed varieties. Over 30 compounds were identified, some of which are thought to possess either nutritional value or are involved in plant disease resistance. This method is expected to be useful for germplasm mining and for varietal development programs in which large numbers of lines are generated.

Antioxidant Vitamins and Risk of Gastric Cancer: A Case-Control Study in Portugal

We quantified the effect of antioxidant vitamins in gastric cancer risk, taking into account Helicobacter pylori seropositivity and overall fruit and vegetable intake. Incident cases were identified in two large hospitals in Porto, Portugal, and controls were randomly sampled among city dwellers. Food intake was assessed with a previously validated semiquantitative food-frequency questionnaire. A commercially available chromatographic immunoassay was used for the detection of immunoglobulin G antibodies. Complete questionnaire information and serum samples were available for 233 cases and 311 controls. Compared with subjects in the lowest tertile of dietary intake, the odds ratios (ORs) for those in the highest were 0.85 (95% confidence interval, CI = 0.45-1.60) for vitamin C, 1.04 (95% CI = 0.60-1.80) for vitamin E, and 1.33 (95% CI = 0.77-2.30) for provitamin A carotenoids after further adjusting for fruit and vegetable consumption. Fruit and vegetables remained an independent protective factor (OR = 0.45; 95% CI = 0.23-0.89) after further adjustment for the intake of antioxidant vitamins. H. pylori status had no significant interaction with dietary items. Factors other than H. pylori infection and intake of vitamin C and provitamin A carotenoids seem to account for the inverse association between fruit and vegetable consumption and gastric cancer.

An overview of the association between allergy and cancer

Numerous epidemiological studies have evaluated some aspect of the association between a history of allergy and cancer occurrence. In this article, an overview of the epidemiological evidence is presented with a discussion of a number of methodological issues important in this area of study. Literature searches were conducted using the MEDLINE database from 1966 through to August 2005 to identify articles that explored a personal history of allergic disorders as a risk factor for cancer. Although it is difficult to draw conclusions between allergy and cancer at many sites because of insufficient evidence or a lack of consistency both within and among studies completed to date, strong inverse associations have been reported for pancreatic cancer and glioma, whereas lung cancer was positively associated with asthma. Additional studies are needed to confirm these finding and to address the limitations of previous studies, including the validity and reliability of exposure measures and control for confounding. Further, large prospective studies using cancer incidence would be particularly useful, including studies using biological markers of allergic status to reduce potential misclassification and to confirm the results of previous studies based on self-report. There is also a need for further basic research to clarify a potential mechanism, should an association exist.

Anthropometric measures in relation to basal cell carcinoma: a longitudinal study

BACKGROUND

The relationship between anthropometric indices and risk of basal cell carcinoma (BCC) is largely unknown. We aimed to examine the association between anthropometric measures and development of BCC and to demonstrate whether adherence to World Health Organisation guidelines for body mass index, waist circumference, and waist/hip ratio was associated with risk of BCC, independent of sun exposure.

METHODS

Study participants were participants in a community-based skin cancer prevention trial in Nambour, a town in southeast Queensland (latitude 26 degrees S). In 1992, height, weight, and waist and hip circumferences were measured for all 1621 participants and weight was remeasured at the end of the trial in 1996. Prevalence proportion ratios were calculated using a log-binomial model to estimate the risk of BCC prior to or prevalent in 1992, while Poisson regression with robust error variances was used to estimate the relative risk of BCC during the follow-up period.

RESULTS

At baseline, 94 participants had a current BCC, and 202 had a history of BCC. During the 5-year follow-up period, 179 participants developed one or more new BCCs. We found no significant association between any of the anthropometric measures or indices and risk of BCC after controlling for potential confounding factors including sun exposure. There was a suggestion that short-term weight gain may increase the risk of developing BCC for women only.

CONCLUSION

Adherence to World Health Organisation guidelines for body mass index, waist circumference and waist/hip ratio is not significantly associated with occurrence of basal cell carcinomas of the skin.

Influence of galangin on HL-60 cell proliferation and survival

The effect of galangin, a flavonol component of India root spice and the 'herbal' medicine propolis, on HL-60 human leukaemia cell survival is characterised. Galangin (1-100 microM) exerted an antiproliferative effect that, with dose and exposure longevity, was progressively associated with an elevated hypodiploid DNA content and expression of the active form of caspase-3, principally prior to membrane damage. At >or=50 microM, plasmamembrane phosphatidylserine exposure was observed. There was no evidence for intracellular oxidative stress as an orchestrator of cytotoxicity and significant phagocyte-like differentiation was not detected. We discuss whether such cytotoxicity will be therapeutically exploitable or contribute to cancer prevention within a pharmacological or dietary context.

Moderate acute intake of de-alcoholized red wine, but not alcohol, is protective against radiation-induced DNA damage ex vivo -- results of a comparative in vivo intervention study in younger men

Moderate intake of wine is associated with reduced risk of cardiovascular disease and possibly cancer however it remains unclear whether the potential health benefits of wine intake are due to alcohol or the non-alcoholic fraction of wine. We therefore tested the hypothesis that the non-alcoholic fraction of wine protects against genome damage induced by oxidative stress in a crossover intervention study involving six young adult males aged 21-26 years. The participants adhered to a low plant phenolic compound diet for 48 h prior to consuming 300 mL of complete red wine, de-alcoholized red wine or ethanol on separate occasions 1 week apart. Blood samples were collected 0.5, 1.0 and 2.0 h after beverage consumption. Baseline and radiation-induced genome damage was measured using the cytokinesis-block micronucleus assay and total plasma catechin concentration was measured. Consumption of de-alcoholized red wine significantly decreased the gamma radiation-induced DNA damage at 1 and 2 h post-consumption by 20%. In contrast alcohol tended to increase radiation-induced genome damage and complete wine protected against radiation-induced genome damage relative to alcohol. The observed effects were only weakly correlated with the concentration of total plasma catechin (R=-0.23). These preliminary data suggest that only the non-alcoholic fraction of red wine protects DNA from oxidative damage but this effect cannot be explained solely by plasma catechin.

Vegetable and fruit intake and pancreatic cancer in a population-based case-control study in the San Francisco bay area

Pancreatic cancer is one of the most devastating and rapidly fatal cancers, yet little is known about the primary cause and prevention of this disease. We conducted a population-based case-control study to investigate the association between vegetables and fruits and pancreatic cancer. Between 1995 and 1999, 532 cases and 1,701 age- and sex-matched controls completed direct interviews using a semiquantitative food-frequency questionnaire. No proxy interviews were conducted. We observed inverse associations between consumption of total and specific vegetables and fruits and the risk of pancreatic cancer. The odds ratio and 95% confidence interval for the highest versus the lowest quartile of total vegetable intake was 0.45 (0.32-0.62), trend P < 0.0001; and for total fruits and fruit juice was 0.72 (0.54-0.98), trend P = 0.06. Odds ratios and 95% confidence intervals for the highest versus the lowest quartile of specific vegetables and fruits were: 0.63 (0.47-0.83) for dark leafy vegetables, 0.76 (0.56-1.0) for cruciferous vegetables, 0.59 (0.43-0.81) for yellow vegetables, 0.56 (0.41-0.76) for carrots, 0.51 (0.38-0.70) for beans, 0.46 (0.33-0.63) for onions and garlic, and 0.78 (0.58-1.0) for citrus fruits and juice. Compared with less than five servings per day of total vegetables and fruits combined, the risk of pancreatic cancer was 0.49 (0.36-0.68) for more than nine servings per day. These results suggest that increasing vegetable and fruit consumption, already recommended for the prevention of several other chronic diseases, may impart some protection against developing pancreatic cancer.

Conference overview: Molecular mechanisms of metal toxicity and carcinogenesis

Chronic exposure to many heavy metals and metal-derivatives is associated with an increased risk of cancer, although the mechanisms of tumorigenesis are largely unknown. Approximately 125 scientists attended the 3rd Conference on Molecular Mechanisms of Metal Toxicity and Carcinogenesis and presented the latest research concerning these mechanisms. Major areas of focus included exposure assessment and biomarker identification, roles of ROS and antioxidants in carcinogenesis, mechanisms of metal-induced DNA damage, metal signalling, and the development of animal models for use in metal toxicology studies. Here we highlight some of the research presented, and summarize the conference proceedings.

Astaxanthin diminishes gap junctional intercellular communication in primary human fibroblasts

Astaxanthin is a carotenoid found in plants and algae; it provides the color of marine seafood such as salmon, lobster, or shrimp. Carotenoids are antioxidants and exhibit other biological functions, including effects on gap junctional communication important for homeostasis, growth control, and development of cells. Cancer cells have an impaired gap junctional intercellular communication. The objective of the present study was to determine the effects of astaxanthin and canthaxanthin on gap junctional intercellular communication in vitro. Primary human skin fibroblasts were exposed to carotenoids from 0.001 to 10 micromol/L, and gap junctional communication was measured with a dye transfer assay. After incubation with canthaxanthin for 24 and 72 h, intercellular communication increased, whereas it was strongly diminished by astaxanthin at levels > 0.1 micromol/L. Inhibition was reversed when astaxanthin was withdrawn. Western blot analysis showed that after exposure to canthaxanthin, the amount of the gap junction protein connexin43 was increased. Incubation with astaxanthin led to a change in the phosphorylation pattern of connexin43, shifting from higher to lower phosphorylation states. We suggest that astaxanthin affects channel function by changing the phosphorylation pattern of connexin43.

REDOX REGULATION BY INTRINSIC SPECIES AND EXTRINSIC NUTRIENTS IN NORMAL AND CANCER CELLS

Cells in multicellular organisms are exposed to both endogenous oxidative stresses generated metabolically and to oxidative stresses that originate from neighboring cells and from other tissues. To protect themselves from oxidative stress, cells are equipped with reducing buffer systems (glutathione/GSH and thioredoxin/thioredoxin reductase) and have developed several enzymatic mechanisms against oxidants that include catalase, superoxide dismutase, and glutathione peroxidase. Other major extrinsic defenses (from the diet) include ascorbic acid, beta-carotene and other carotenoids, and selenium. Recent evidence indicates that in addition to their antioxidant function, several of these redox species and systems are involved in regulation of biological processes, including cellular signaling, transcription factor activity, and apoptosis in normal and cancer cells. The survival and overall well-being of the cell is dependent upon the balance between the activity and the intracellular levels of these antioxidants as well as their interaction with various regulatory factors, including Ref-1, nuclear factor-kappaB, and activating protein-1.

Cancer mortality among US men and women with asthma and hay fever

The relation between self-reported physician-diagnosed asthma and/or hay fever and cancer mortality was explored in a prospective cohort study of 1,102,247 US men and women who were cancer-free at baseline. During 18 years of follow-up, from 1982 to 2000, there were 81,114 cancer deaths. Cox proportional hazards models were used to obtain adjusted relative risks for all cancer mortality and for cancer mortality at 12 sites associated with allergy indicators. There were significant inverse associations between a history of both asthma and hay fever and overall cancer mortality (relative risk (RR) = 0.88, 95% confidence interval (CI): 0.83, 0.93) and colorectal cancer mortality (RR = 0.76, 95% CI: 0.64, 0.91) in comparison with persons with neither of these allergic conditions. A history of hay fever only was associated with a significantly lowered risk of pancreatic cancer mortality, and a history of asthma only was associated with a significantly lowered risk of leukemia mortality. In never smokers, these associations persisted but were no longer significant. Results for mortality from cancer at other sites were less consistent. Collectively, these results suggest an inverse association between a history of allergy and cancer mortality; however, the strength of evidence for this association is limited.

The role of dietary factors in cancer prevention: beyond fruits and vegetables

Cancer, a disease resulting from dysregulated cell growth control, is caused by an interaction of dietary, genetic, and environmental risk factors. Dietary factors, including physical activity, may contribute to approximately one-third of all cancers. This meta-review summarizes dietary factor and cancer risk associations and makes specific dietary recommendations to reduce risk of specific cancers. The evidence supporting specific dietary recommendations to reduce the risk of cancer is heterogeneous in its strength and consistency. Prospective epidemiologic studies have provided strong evidence supporting regular physical activity and minimal adult weight gain to lower risk of colorectal and breast cancer. The strongest evidence linking specific foods to decrease risk of certain cancers includes the consumption of fruits and vegetables and whole grains. Secondary prevention trials and observational prospective epidemiologic studies have demonstrated the efficacy of a Mediterranean-type dietary pattern to decrease risk of both cancer and cardiovascular diseases. We recommend the adoption of dietary patterns emphasizing regular physical activity, fruits and vegetables, whole grains, legumes, nuts, seeds, and low-fat dairy products to all people at risk for cancer and cardiovascular disease. These recommendations may be incorporated into enjoyable cultural food patterns as exemplified by Mediterranean-type diets. The preparation and enjoyment of meals in a convivial atmosphere is a vital component of lifestyles to prevent chronic diseases such as cancer and certain cardiovascular diseases.

Folate and its preventive potential in colorectal carcinogenesis

Based on a 15-year old hypothesis, it is believed that an adequate ingestion of folate vitamins decreases, whereas a nutritional depletion of folate increases the risk of colorectal cancer. The present article reviews the efforts to provide biochemical and epidemiological evidence for folate as a chemopreventive agent against colorectal carcinogenesis. BIOLOGICAL EVIDENCE: Tetrahydrofolates govern the intracellular one-carbon metabolism and account for proper DNA biosynthesis and macromolecular modification. Numerous experimental studies traced different molecular pathways and tried to link folate depletion with DNA instability and/or mutagenesis. However, none of the proposed underlying molecular mechanisms appear clearly defined. EPIDEMIOLOGICAL EVIDENCE: Numerous case-control and prospective studies have been conducted on folate and colorectal cancer, which all together miss a clinical bottom line. The recommendation of folate intake to prevent colorectal cancer is therefore not evidence-based.