Dietary vitamins E and C and prostate cancer risk

Long-Term Exposure to Nitrate and Trihalomethanes in Drinking Water and Prostate Cancer: A Multicase-Control Study in Spain (MCC-Spain)

BACKGROUND

Nitrate and trihalomethanes (THMs) in drinking water are widespread and are potential human carcinogens.

OBJECTIVE

We evaluated the association between drinking-water exposure to nitrate and THMs and prostate cancer.

METHODS

During the period 2008-2013, 697 hospital-based incident prostate cancer cases (97 aggressive tumors) and 927 population-based controls were recruited in Spain, providing information on residential histories and type of water consumed. Average nitrate and THMs levels in drinking water were linked with lifetime water consumption to calculate waterborne ingestion. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models with recruitment area as random effect. Effect modification by tumor grade (Gleason score), age, education, lifestyle, and dietary factors was explored.

RESULTS

Mean (±standard deviation) adult lifetime waterborne ingested nitrate (milligrams per day), brominated (Br)-THMs (micrograms per day), and chloroform (micrograms per day) were 11.5 (±9.0), 20.7 (±32.4), and 15.1 (±14.7) in controls. Waterborne ingested nitrate >13.8 vs. <5.5mg/d was associated with an OR of 1.74 (95% CI: 1.19, 2.54) overall, and 2.78 (95% CI: 1.23, 6.27) for tumors with Gleason scores ≥8. Associations were higher in the youngest and those with lower intakes of fiber, fruit/vegetables, and vitamin C. Waterborne ingested THMs were not associated with prostate cancer. Residential tap water levels of Br-THMs and chloroform showed, respectively, inverse and positive associations with prostate cancer.

CONCLUSIONS

Findings suggest long-term waterborne ingested nitrate could be a risk factor of prostate cancer, particularly for aggressive tumors. High intakes of fiber, fruit/vegetables and vitamin C may lower this risk. Association with residential levels but not ingested chloroform/Br-THM may suggest inhalation and dermal routes could be relevant for prostate cancer. https://doi.org/10.1289/EHP11391.

Why Do Dietary Flavonoids Have a Promising Effect as Enhancers of Anthracyclines? Hydroxyl Substituents, Bioavailability and Biological Activity

Anthracyclines currently play a key role in the treatment of many cancers, but the limiting factor of their use is the widespread phenomenon of drug resistance and untargeted toxicity. Flavonoids have pleiotropic, beneficial effects on human health that, apart from antioxidant activity, are currently considered small molecules-starting structures for drug development and enhancers of conventional therapeutics. This paper is a review of the current and most important data on the participation of a selected series of flavonoids: chrysin, apigenin, kaempferol, quercetin and myricetin, which differ in the presence of an additional hydroxyl group, in the formation of a synergistic effect with anthracycline antibiotics. The review includes a characterization of the mechanism of action of flavonoids, as well as insight into the physicochemical parameters determining their bioavailability in vitro. The crosstalk between flavonoids and the molecular activity of anthracyclines discussed in the article covers the most important common areas of action, such as (1) disruption of DNA integrity (genotoxic effect), (2) modulation of antioxidant response pathways, and (3) inhibition of the activity of membrane proteins responsible for the active transport of drugs and xenobiotics. The increase in knowledge about the relationship between the molecular structure of flavonoids and their biological effect makes it possible to more effectively search for derivatives with a synergistic effect with anthracyclines and to develop better therapeutic strategies in the treatment of cancer.

Vitamin E Intake and Risk of Prostate Cancer: A Meta-Analysis

Vitamin E is a group of antioxidative tocopherols and tocotrienols that play a potential role in chemoprevention. Studies investigating the association between vitamin E and prostate cancer risk have been conflicting. We identified observational and interventional studies examining the association between vitamin E intake and prostate cancer risk from PubMed, EMBASE and the Cochrane Library. A random-effects model was used to perform a meta-analysis and estimate relative risks (RRs) and the corresponding 95% confidence intervals (CIs) of prostate cancer risk according to vitamin E intake. Subgroup analyses were conducted by study design, sample size, study population characteristics, geographical region, and dose of vitamin E intake. The association between dietary (RR = 0.97; 95% CI = 0.92-1.02) and supplemental (RR = 0.99; 95% CI = 0.94-1.04) vitamin E intake on prostate cancer risk was non-significant. In subgroup analyses, supplemental vitamin E was significantly associated with reduced prostate cancer risk in studies in Europe (RR = 0.81, 95% CI = 0.69-0.97). Overall, this meta-analysis demonstrates little evidence for a beneficial effect of vitamin E intake on prostate cancer risk but suggests that there may be some conditions in which supplements could confer a protective effect on prostate cancer risk.

Genome-wide Expression Analysis Identifies the Association between SEC14L2 and Castration-resistant Prostate Cancer Survival

Background: Mechanism of castration-resistant prostate cancer (CRPC) is still unclear. Our objective is to investigate the association between genes expression and CRPC through the genome-wide approach and functional researches.

Methods: Differentially expressed genes (DEGs) between PCa and CRPC tissues were identified using expression profile obtained from Gene Expression Omnibus database (GEO). Survival analysis was performed using online database Gene Expression Profiling Interactive Analysis (GEPIA). Oncomine database was further used to explore the relationship between DEGs expression levels with clinical parameters. After in silico study, SEC14L2-knockdown CRPC cells and normal prostatic epithelial cells were used for in vitro study to verify its biological functions.

Results: A total of 3 consistently changed DEGs (SEC14L2, DMD, SEL1L) were identified correlating with CRPC after cross validation in three independent datasets. Low expression of SEC14L2 was associated with poorer disease-free survival and higher Gleason score than normal/high expression of SEC14L2. SEC14L2 knockdown promoted cell proliferation, migration, invasion as well as cell cycle progression in CRPC cells (all P<0.05) while no significant effects were observed in normal prostatic epithelial cells.

Conclusions: Low expression of SEC14L2 was significantly associated with CRPC, and correlated with PCa aggressiveness and poorer prognosis. SEC14L2 might be a potential biomarker or drug target for CRPC.

Impact of oxidative stress SNPs and dietary antioxidant quality score on prostate cancer

Purpose: To analyse the relation between antioxidant genotypes and Dietary Antioxidant Quality score (DAQs) effect on prostate cancer (PCa) risk and aggressiveness in a Spanish population.Methods: Men (N = 155 patients and 152 controls) with PSA values >4 ng/ml were enrolled in the project. DAQs were used considering the daily recommended intake for Spanish people (DRI). Genotyping of 5 SNPs rs662 (PON1), rs10432782 (SOD1), rs4880 (SOD2), rs17650792 (GPX1) and rs1001179 (CAT) were included for the analysis.Results: rs17650792 was statistically significant between case and controls subjects. When comparing D´Amico risk, we found that rs662 (CC), rs10432782 (G allele) and rs17650792 (GG) confer a protection. When testing SNP-antioxidant nutrients interactions, we found an intake of vitamin A and rs100179 (T carriers) and selenium and rs17650792 (G carriers) confers a protection of being in low risk classification.Conclusions: We reported by the first time a correlation between rs662 (PON1) and PCa aggressiveness.

Dietary Nutrient Patterns and Prostate Cancer Risk: A Case-Control Study from Iran

Background:

Prostate cancer is the second common cancer in the world. Although some associations between dietary intakes and prostate cancer have been found, the effects of dietary nutrients interactions have not yet evaluated. The aim of this study is to assess the association between nutrient patterns and risk of prostate cancer.

Methods and Materials:

Ninety-seven patients with prostate cancer and 205 controls were asked about their demographic and dietary intakes using validated questionnaires. To extract nutrient patterns, Principal Component Analysis (PCA) based on the 35 nutrient items were applied. Varimax rotation was used for improving interpretation and minimizing correlation between the factors. Logistic regression was used to determine the odds ratio (OR) with 95% confidence interval (CI) of prostate cancer by higher scores on the nutrient patterns.

Results:

High adherence to the “plant source” pattern was negatively associated with prostate cancer risk (OR 0.29 for the highest vs. the lowest score tertile; 95% CI= 0.13 – 0.65; P value for trend: <0.003). Similarly, the “antioxidant and fiber” pattern was associated with decreasing risk of prostate cancer (OR 0.06 for the highest vs. the lowest score tertile;95% CI=0.02 – 0.19; P value for trend: <0.001). There was no significant association for the “mixed” and “vitamin and minerals” pattern with risk of prostate cancer.

Conclusion:

This study confirms the potential and important role of nutrients on prostate cancer risk. Our finding revealed that “antioxidant and fiber” and “plant source” pattern is inversely associated with prostate cancer risk; however, further longitudinal and trial studies are needed to make a firm conclusion.

Bioactive compounds of the Mediterranean diet and prostate cancer

OBJECTIVE

The purpose of this review is to examine the evidence on the effects of bioactive constituents of the Mediterranean diet (MeDi) on prostate cancer (PCa) risk.

METHODS

The search for articles came from extensive research in the following databases: PubMed, Scopus, and Web of Science. We used the search terms "Mediterranean diet," "lycopene," "vitamin E," "vitamin C," "Selenium," "resveratrol," "prostate cancer," and combinations, such as "lycopene and prostate cancer" or "resveratrol and prostate cancer."

RESULTS

Numerous studies investigating the effect of various dietary nutrients on PCa have suggested that selenium is probably the most promising. Several studies reported reduced PCa risk associated with vitamin C and E intake, while other studies reported no association. Lycopene inhibits cell proliferation and inducts apoptosis, thus protecting against cancer. Also, it has been found in various in vivo and in vitro studies that resveratrol, inhibits PCa development.

CONCLUSIONS

The high content of bioactive phytochemicals in the MeDi is of particular interest in the prevention of PCa. Further large-scale studies are required to clarify the effect of MeDi bioactive compounds on prostate health, in order to establish the role of this diet in the prevention of PCa.

Oxidative stress in prostate hyperplasia and carcinogenesis

Prostatic hyperplasia (PH) is a common urologic disease that affects mostly elderly men. PH can be classified as benign prostatic hyperplasia (BPH), or prostate cancer (PCa) based on its severity. Oxidative stress (OS) is known to influence the activities of inflammatory mediators and other cellular processes involved in the initiation, promotion and progression of human neoplasms including prostate cancer. Scientific evidence also suggests that micronutrient supplementation may restore the antioxidant status and hence improve the clinical outcomes for patients with BPH and PCa. This review highlights the recent studies on prostate hyperplasia and carcinogenesis, and examines the role of OS on the molecular pathology of prostate cancer progression and treatment.

Dietary Total Antioxidant Capacity is Inversely Associated with Prostate Cancer Aggressiveness in a Population-Based Study

The purpose of this study was to determine the relationship between total antioxidant capacity (TAC) from diet and supplements and prostate cancer aggressiveness among 855 African Americans (AA) and 945 European Americans (EA) in the North Carolina-Louisiana Prostate Cancer Project (PCaP). Cases were classified as either high aggressive, low aggressive, or intermediate aggressive. TAC was calculated from the vitamin C equivalent antioxidant capacity of 42 antioxidants measured via food frequency questionnaire. EA reported greater dietary TAC from diet and supplements combined (P < 0.0001). In both minimally and fully adjusted logistic regression models, TAC from diet and supplements combined was associated with a reduced odds of high aggressive prostate cancer in all men, AA and EA: odds ratios for highest vs. lowest level (>1500 vs. <500 mg vitamin C equivalent/day): 0.31 [95% confidence interval (CI): 0.15, 0.67; P-trend < 0.01], 0.28 (95% CI: 0.08, 0.96; P-trend < 0.001), and 0.36 (95% CI: 0.15, 0.86; P-trend = 0.58), respectively. These associations did not appear to differ between AA and EA. These data suggest that greater intake of antioxidants is associated with less aggressive prostate cancer. Additional research is needed to confirm these results and determine the underlying mechanisms.

Selenium and vitamin E for prostate cancer--justifications for the SELECT study

There are several studies that relate oxidative damage as possible mechanism for many cancers. Many studies have also shown that anti-oxidants like selenium and vitamin E decrease the risk for prostate cancer. The main objective of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) study was to look for the benefits of selenium and vitamin E supplementation on prostate cancer. The study had a large sample size, stringent experimental conditions, very long duration, standardized laboratories for biochemical analyses and other factors that contribute to high external validity. The SELECT study failed to show any significant risk reduction for prostate cancers ascribable to selenium and vitamin E supplementations. Because of these conflicting results, many researchers argue about the methods used, supplementations administered (selenium and vitamin E) and indicators used for assessing levels of supplementations. We reviewed many epidemiological studies, clinical trials, and pre-clinical studies. With corroborative evidences we justify that SELECT study has a sound methodology and rationale. In lieu of the contrary results of the select study, researchers should focus on the probable mechanisms for these contrary findings and continue their search for newer and effective agents for prevention of prostate cancer.

Association between Dietary Vitamin C Intake and Risk of Prostate Cancer: A Meta-analysis Involving 103,658 Subjects

We attempted to systematically determine the association between dietary intake of vitamin C and risk of prostate cancer. PubMed and Embase were searched to obtain eligible studies published before February 2015. Cohort or case-control studies that reported the relative risk (RR)/odds ratio (OR) estimates with 95% confidence intervals (CIs) for the association between vitamin C intake and prostate cancer risk were included. Eighteen studies regarding dietary vitamin C intake were finally obtained, with a total of 103,658 subjects. The pooled RR of prostate cancer for the highest versus the lowest categories of dietary vitamin C intake was 0.89 (95%CI: 0.83-0.94; p = 0.000) with evidence of a moderate heterogeneity (I(2) = 39.4%, p = 0.045). Meta-regression analysis suggested that study design accounted for a major proportion of the heterogeneity. Stratifying the overall study according to study design yielded pooled RRs of 0.92 (95%CI: 0.86-0.99, p = 0.027) among cohort studies and 0.80 (95%CI: 0.71-0.89, p = 0.000) among case-control studies, with no heterogeneity in either subgroup. In the dose-response analysis, an inverse linear relationship between dietary vitamin C intake and prostate cancer risk was established, with a 150 mg/day dietary vitamin C intake conferred RRs of 0.91 (95%CI: 0.84-0.98, p = 0.018) in the overall studies, 0.95 (95%CI: 0.90-0.99, p = 0.039) in cohort studies, and 0.79 (95%CI: 0.69-0.91, p = 0.001) in case-control studies. In conclusion, intake of vitamin C from food was inversely associated with prostate cancer risk in this meta-analysis.

Oxidative balance score and risk for incident prostate cancer in a prospective U.S. cohort study

PURPOSE

Oxidative stress is defined as an imbalance between pro-oxidants and antioxidants. Previous research found that a single comprehensive oxidative balance score (OBS) that includes individual pro- and anti-oxidant exposures may be associated with various conditions (including prostate cancer) in the absence of associations with the individual factors. We investigated an OBS-incident prostate cancer association among 43,325 men in the Cancer Prevention Study II Nutrition Cohort.

METHODS

From 1999-2007, 3386 incident cases were identified. Twenty different components, used in two ways (unweighted or weighted based on literature reviews), were incorporated into the OBS, and the resulting scores were then expressed as three types of variables (continuous, quartiles, or six equal intervals). Multivariable-adjusted rate ratios were calculated using Cox proportional hazards models.

RESULTS

We hypothesized that the OBS would be inversely associated with prostate cancer risk; however, the rate ratios (95% confidence intervals) comparing the highest with the lowest OBS categories ranged from 1.17 (1.04-1.32) to 1.39 (0.90-2.15) for all cases, 1.14 (0.87-1.50) to 1.59 (0.57-4.40) for aggressive disease (American Joint Committee on Cancer stage III/IV or Gleason score 8-10), and 0.91 (0.62-1.35) to 1.02 (1.02-1.04) for nonaggressive disease.

CONCLUSIONS

Our findings are not consistent with the hypothesis that oxidative balance-related exposures collectively affect risk for prostate cancer.

Dietary antioxidants and prostate cancer: a review

Prostate cancer is the most common noncutaneous cancer in men in the United States. Several studies have examined the relationship between prostate cancer and antioxidants; however, the results of these studies are inconsistent. This article provides a systematic review of studies on prostate cancer and antioxidant intake from diet and supplements. Tea and coffee appear to offer protection against advanced prostate cancer. Different forms of vitamin E appear to exert different effects on prostate cancer, with alpha-tocopherol potentially increasing and gamma-tocopherol potentially decreasing risk of the disease. There is no strong evidence for a beneficial effect of selenium, vitamin C, or beta-carotene, whereas lycopene appears to be negatively associated with risk of the disease. The effect of dietary antioxidants on prostate cancer remains undefined and inconclusive, with different antioxidants affecting prostate cancer risk differentially. Further studies are needed to clarify the relationship between antioxidants and prostate cancer risk and to delineate the underlying mechanisms.

Tea consumption and the risk of overall and grade specific prostate cancer: a large prospective cohort study of Scottish men

Tea may be a potentially modifiable and highly prevalent risk factor for the most common cancer in men, prostate cancer. However, associations between black tea consumption and prostate cancer in epidemiological studies have been inconsistent, limited to a small number of studies with small numbers of cases and short follow-up periods and without grade-specific information. We conducted a prospective cohort study of 6,016 men who were enrolled in the Collaborative Cohort Study between 1970 and 1973 and followed up to December 31, 2007. We used Cox proportional hazards models to investigate the association between tea consumption and overall as well as grade-specific risk of prostate cancer incidence. Three hundred and eighteen men developed prostate cancer in up to 37 years of follow-up. We found a positive association between consumption of tea and overall risk of prostate cancer incidence (P = 0.02). The association was greatest among men who drank ≥ 7 cups of tea per day (HR: 1.50, 95% CI: 1.06 to 2.12), compared with the baseline of 0-3 cups/day. However, we did not find any significant association between tea intake and low- (Gleason <7) or high-grade (Gleason 8-10) prostate cancer incidence. Men with higher intake of tea are at greater risk of developing prostate cancer, but there is no association with more aggressive disease. Further research is needed to determine the underlying biological mechanisms for the association.

Vitamins and prostate cancer risk

Prostate cancer (PC) is the second most common cancer in men worldwide. Its prevention and treatment remain a challenge to clinicians. Here we review the relationship of vitamins to PC risk. Many vitamins and related chemicals, including vitamin A, retinoids, several B vitamins, vitamin C, vitamin D and vitamin E have shown their anti-cancer activities as anti-oxidants, activators of transcription factors or factors influencing epigenetic events. Although laboratory tests including the use of animal models showed these vitamins may have anti-PC properties, whether they can effectively prevent the development and/or progression of PC in humans remains to be intensively studied subjects. This review will provide up-to-date information regarding the recent outcomes of laboratory, epidemiology and/or clinical trials on the effects of vitamins on PC prevention and/or treatment.