Estimated phytanic acid intake and prostate cancer risk: a prospective cohort study

Amelioration of Phytanic Acid-Induced Neurotoxicity by Nutraceuticals: Mechanistic Insights

Phytanic acid (PA) (3,7,11,15-tetramethylhexadecanoic acid) is a methyl-branched fatty acid that enters the body through food consumption, primarily through red meat, dairy products, and fatty marine foods. The metabolic byproduct of phytol is PA, which is then oxidized by the ruminal microbiota and some marine species. The first methyl group at the 3-position prevents the β-oxidation of branched-chain fatty acid (BCFA). Instead, α-oxidation of PA results in the production of pristanic acid (2,10,14-tetramethylpentadecanoic acid) with CO2. This fatty acid (FA) builds up in individuals with certain peroxisomal disorders and is historically linked to neurological impairment. It also causes oxidative stress in synaptosomes, as demonstrated by an increase in the production of reactive oxygen species (ROS), which is a sign of oxidative stress. This review concludes that the nutraceuticals (melatonin, piperine, quercetin, curcumin, resveratrol, epigallocatechin-3-gallate (EGCG), coenzyme Q10, ω-3 FA) can reduce oxidative stress and enhanced the activity of mitochondria. Furthermore, the use of nutraceuticals completely reversed the neurotoxic effects of PA on NO level and membrane potential. Additionally, the review further emphasizes the urgent need for more research into dairy-derived BCFAs and their impact on human health.

Calcium Activation of the Androgen Receptor in Prostate Cells

Background

Although prostate cancer patients initially respond to androgen deprivation therapy, most patients progress to a resistant phenotype. Castration resistance is due, in part, to intratumoral and/or adrenal synthesis of androgens, overexpression or mutation of the androgen receptor (AR), stabilization of AR by chaperones, and ligand-independent activation of AR. Increasing evidence also links disruption of calcium homeostasis to progression of prostate cancer. Our previous study shows that heavy metal cadmium activates the AR through a ligand-independent mechanism. Cadmium mimics calcium in biological systems due to their similar ionic charge and radius. This study determines whether calcium activates AR and whether first- and second-generation antiandrogens block the ability of calcium to activate the receptor.

Methods

The expression of androgen-responsive genes and calcium channels was measured in prostate cells using a quantitative real-time polymerase chain reaction assay. Cell growth was measured.

Results

To ask whether calcium activates AR, prostate cells were treated with calcium in the absence and presence of the first-generation antiandrogens hydroxyflutamide and bicalutamide and the second-generation antiandrogen enzalutamide, and the expression of androgen-responsive genes and cell growth was measured. In the normal PWR-1E cells and HEK293T cells transiently expressing AR, treatment with calcium increased the expression of androgen-responsive genes by approximately 3-fold. The increase was blocked by enzalutamide but was not consistently blocked by the first-generation antiandrogens. In LNCaP cells which contain a mutant AR, treatment with calcium also increased the expression of androgen-responsive genes by approximately 3-fold, and the increase was more effectively blocked by enzalutamide than by hydroxyflutamide or bicalutamide. Treatment with calcium also increased cell growth that was blocked by enzalutamide. To ask whether dysregulation of calcium channels is associated with castration resistance, calcium channels were measured in the normal PWR-1E prostate cells, the hormone-responsive LNCaP cells, and the castration-resistant VCaP and 22RV1 cells. Compared to normal prostate cells, the hormone-responsive and hormone-resistant cells overexpressed several calcium channels.

Conclusions

The results of this study show that calcium activates AR and increases cell growth and that calcium channels are overexpressed in hormone-responsive and hormone-resistant prostate cancer cells. Taken together, the results suggest a novel role of calcium in the castration-resistant phenotype.

Phytanic acid, an inconclusive phytol metabolite: A review

Phytanic acid (PA: 3,7,11,15-tetramethylhexadecanoic acid) is an important biometabolite of the chlorophyll-derived diterpenoid phytol. Its biological sources (occurrence) and ADME (absorption, distribution, metabolism, and elimination) profile are well-discussed in the literature. Cumulative literature suggests that PA has beneficial as well as harmful biological roles in humans and other animals. This study aimed to sketch a brief summary of PA's beneficial and harmful pharmacological effects in test systems on the basis of existing literature reports. Literature findings propose that PA has anti-inflammatory and immunomodulatory, antidiabetic, anti-obesity, anticancer, and oocyte maturation effects. Although a high plasma PA-level mediated SLS remains controversial, it is evident to link it with Refsum's disease and other peroxisomal enzyme deficiency diseases in humans, including RCDP and LD; ZHDA and Alzheimer's disease; progressive ataxia and dysarthria; and an increased risk of some lymphomas such as LBL, FL, and NHL. PA exerts toxic effects on different kinds of cells, including neuronal, cardiac, and renal cells, through diverse pathways such as oxidative stress, mitochondrial disturbance, apoptosis, disruption of Na+/K+-ATPase activity, Ca2+ homeostasis, alteration of AChE and MAO activities, etc. PA is considered a cardiac biomarker in humans. In conclusion, PA may be one of the most important biometabolites in humans.

Fish consumption and risk of prostate cancer or its mortality: an updated systematic review and dose-response meta-analysis of prospective cohort studies

Since the release of the last meta-analysis on the association between fish intake and prostate cancer risk, several cohort studies have been published. Moreover, none of the previous meta-analyzes examined the dose-response association between fish intake and prostate cancer. Therefore, the current dose-response meta-analysis was conducted to summarize available findings on the associations of fish intake with the risk of prostate cancer in men. Online databases of PubMed, Scopus, and Web of Science were systematically searched up to September 2022. We included prospective cohort studies that examined the associations of fish intake with the risk of prostate cancer (total, localized, and advanced prostate cancer), its mortality, and cancer progression. Summary relative risks (RR) and 95% confidence intervals (CI) were calculated for the highest versus lowest categories of fish intake using random-effects models. Also, linear and non-linear dose-response analyzes were conducted. In total, 25 prospective cohort studies, recruiting 1,216,474 men, were included in the systematic review, and 22 studies were included in the meta-analysis. During the follow-up periods, ranging from 6 to 33 years, a total of 44,722 cases of prostate cancer were recorded. The comparison between the highest and lowest intakes of total fish revealed the summary RRs of 0.97 (95% CI: 0.86-1.10) for total, 1.01 (95% CI: 0.91-1.13) for advanced, and 0.90 (95% CI: 0.72-1.12) for localized prostate cancer, indicating no significant association. Moreover, the summary RR was 0.55 (95% CI: 0.33-0.92) for prostate cancer mortality and 0.84 (95% CI: 0.65-1.10) for prostate cancer progression, indicating an inverse association between fish intake and prostate cancer mortality. Also, in the dose-response analyzes, each 20 gram/day increase in total fish intake was associated with a 12% lower risk of prostate cancer mortality. Our findings support the protective association between total fish intake and the risk of prostate cancer mortality.

Metabolomic analysis of serum alpha-tocopherol among men in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study

BACKGROUND/OBJECTIVES

The role of vitamin E in chronic disease risk remains incompletely understood, particularly in an un-supplemented state, and evidence is sparse regarding the biological actions and pathways involved in its influence on health outcomes. Identifying vitamin-E-associated metabolites through agnostic metabolomics analyses can contribute to elucidating the specific associations and disease etiology. This study aims to investigate the association between circulating metabolites and serum α-tocopherol concentration in an un-supplemented state.

SUBJECTS/METHODS

Metabolomic analysis of 4,294 male participants was conducted based on pre-supplementation fasting serum in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The associations between 1,791 known metabolites measured by ultra-high-performance LC-MS/GC-MS and HPLC-determined α-tocopherol concentration were estimated using multivariable linear regression. Differences in metabolite levels per unit difference in α-tocopherol concentration were calculated as standardized β-coefficients and standard errors.

RESULTS

A total of 252 metabolites were associated with serum α-tocopherol at the Bonferroni-corrected p value (p < 2.79 × 10^-5). Most of these metabolites were of lipid and amino acid origin, with the respective subclasses of dicarboxylic fatty acids, and valine, leucine, and isoleucine metabolism, being highly represented. Among lipids, the strongest signals were observed for linoleoyl-arachidonoyl-glycerol (18:2/20:4)[2](β = 0.149; p = 8.65 × 10^-146) and sphingomyelin (D18:2/18:1) (β = 0.035; p = 1.36 × 10^-30). For amino acids, the strongest signals were aminoadipic acid (β = 0.021; p = 5.01 × 10^-13) and l-leucine (β = 0.007; p = 1.05 × 10^-12).

CONCLUSIONS

The large number of metabolites, particularly lipid and amino acid compounds associated with serum α-tocopherol provide leads regarding potential mechanisms through which vitamin E influences human health, including its role in cardiovascular disease and cancer.

Association Between Red and Processed Meat Consumption and Risk of Prostate Cancer: A Systematic Review and Meta-Analysis

Background

Debate on the potential carcinogenic effects of meat intake is open and the relationship between meat consumption and risk of prostate cancer remains uncertain. This meta-analysis was conducted to summarize earlier prospective studies on the association of meat consumption with risk of prostate cancer.

Methods

Relevant studies were identified by exploring PubMed/Medline, Scopus, Web of Science, EMBASE, and Google Scholar databases up to December 2020. Fixed-effects and random-effects meta-analyses were used for pooling the relative risks (RRs). Heterogeneity across studies was evaluated using the Q-statistic and I-square (I²). A funnel plot and Egger's test was used to detect publication bias. Linear and non-linear dose-response analyses were performed to estimate the dose-response relations between meat intake and risk of prostate cancer.

Results

Twenty-five prospective studies were included in this meta-analysis. Totally, 1,900,910 participants with 35,326 incident cases of prostate cancer were investigated. Pooling the eligible effect sizes, we observed that high consumption of processed meat might be associated with an increased risk of “total prostate cancer” (RR: 1.06; 95% CI: 1.01, 1.10; I² = 1.5%, P = 0.43) and “advanced prostate cancer” (1.17; 1.09, 1.26; I² = 58.8%, P = 0.01). However, the association between processed meat and “advanced prostate cancer” was not significant in the random-effects model: 1.12 (95% CI: 0.98, 1.29). A linear dose-response analysis indicated that an increment of 50 grams per day of processed meat intake might be related to a 4% greater risk of “total prostate cancer” (1.04; 1.00, 1.08; I² = 0.0%, P = 0.51). “Total meat intake” was marginally associated with all outcomes of prostate cancer risk (1.04; 1.01, 1.07; I² = 58.4%, P < 0.001).

Conclusions

This systematic review and meta-analysis of prospective studies indicated that increased consumption of “total meat” and “processed meat” might be associated with a higher risk of prostate cancer.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=230824, identifier: CRD42021230824.

Consumption of red meat and processed meat and cancer incidence: a systematic review and meta-analysis of prospective studies

Red meat and processed meat consumption has been hypothesized to increase risk of cancer, but the evidence is inconsistent. We performed a systematic review and meta-analysis of prospective studies to summarize the evidence of associations between consumption of red meat (unprocessed), processed meat, and total red and processed meat with the incidence of various cancer types. We searched in MEDLINE and EMBASE databases through December 2020. Using a random-effect meta-analysis, we calculated the pooled relative risk (RR) and 95% confidence intervals (CI) of the highest versus the lowest category of red meat, processed meat, and total red and processed meat consumption in relation to incidence of various cancers. We identified 148 published articles. Red meat consumption was significantly associated with greater risk of breast cancer (RR = 1.09; 95% CI = 1.03-1.15), endometrial cancer (RR = 1.25; 95% CI = 1.01-1.56), colorectal cancer (RR = 1.10; 95% CI = 1.03-1.17), colon cancer (RR = 1.17; 95% CI = 1.09-1.25), rectal cancer (RR = 1.22; 95% CI = 1.01-1.46), lung cancer (RR = 1.26; 95% CI = 1.09-1.44), and hepatocellular carcinoma (RR = 1.22; 95% CI = 1.01-1.46). Processed meat consumption was significantly associated with a 6% greater breast cancer risk, an 18% greater colorectal cancer risk, a 21% greater colon cancer risk, a 22% greater rectal cancer risk, and a 12% greater lung cancer risk. Total red and processed meat consumption was significantly associated with greater risk of colorectal cancer (RR = 1.17; 95% CI = 1.08-1.26), colon cancer (RR = 1.21; 95% CI = 1.09-1.34), rectal cancer (RR = 1.26; 95% CI = 1.09-1.45), lung cancer (RR = 1.20; 95% CI = 1.09-1.33), and renal cell cancer (RR = 1.19; 95% CI = 1.04-1.37). This comprehensive systematic review and meta-analysis study showed that high red meat intake was positively associated with risk of breast cancer, endometrial cancer, colorectal cancer, colon cancer, rectal cancer, lung cancer, and hepatocellular carcinoma, and high processed meat intake was positively associated with risk of breast, colorectal, colon, rectal, and lung cancers. Higher risk of colorectal, colon, rectal, lung, and renal cell cancers were also observed with high total red and processed meat consumption.

Intake of individual fatty acids and risk of prostate cancer in the European prospective investigation into cancer and nutrition

The associations of individual dietary fatty acids with prostate cancer risk have not been examined comprehensively. We examined the prospective association of individual dietary fatty acids with prostate cancer risk overall, by tumor subtypes, and prostate cancer death. 142,239 men from the European Prospective Investigation into Cancer and Nutrition who were free from cancer at recruitment were included. Dietary intakes of individual fatty acids were estimated using center-specific validated dietary questionnaires at baseline and calibrated with 24-h recalls. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). After an average follow-up of 13.9 years, 7,036 prostate cancer cases and 936 prostate cancer deaths were ascertained. Intakes of individual fatty acids were not related to overall prostate cancer risk. There was evidence of heterogeneity in the association of some short chain saturated fatty acids with prostate cancer risk by tumor stage (pheterogeneity < 0.015), with a positive association with risk of advanced stage disease for butyric acid (4:0; HR1SD = 1.08; 95%CI = 1.01-1.15; p-trend = 0.026). There were no associations with fatal prostate cancer, with the exception of a slightly higher risk for those who consumed more eicosenoic acid (22:1n-9c; HR1SD = 1.05; 1.00-1.11; p-trend = 0.048) and eicosapentaenoic acid (20:5n-3c; HR1SD = 1.07; 1.00-1.14; p-trend = 0.045). There was no evidence that dietary intakes of individual fatty acids were associated with overall prostate cancer risk. However, a higher intake of butyric acid might be associated with a higher risk of advanced, whereas intakes of eicosenoic and eicosapentaenoic acids might be positively associated with fatal prostate cancer risk.

Do dietary calcium and vitamin D matter in men with prostate cancer?

Active surveillance (AS) is an attractive alternative to immediate treatment for men with low-risk prostate cancer. Thus, the identification of environmental factors that promote the progression of indolent disease towards aggressive stages is critical to optimize clinical management. Epidemiological studies suggest that calcium-rich diets contribute to an increased risk of developing prostate cancer and that vitamin D reduces this risk. However, the potential effect of these nutrients on the progression of early-stage prostate tumours is uncertain, as studies in this setting are scarce and have not provided unambiguous conclusions. By contrast, the results of a preclinical study from our own group demonstrate that a diet high in calcium dose-dependently accelerated the progression of early-stage prostate tumours and that dietary vitamin D prevented this effect. The extent to which the conclusions of preclinical and epidemiological studies support a role for calcium and vitamin D and the relevance of monitoring and adjustment of calcium and/or vitamin D intake in patients on AS require further investigation.

Phytol and its metabolites phytanic and pristanic acids for risk of cancer: current evidence and future directions

This review summarizes the current evidence on the potential role of phytol, a microbial metabolite of chlorophyl A, and its metabolites, phytanic and pristanic acids, in carcinogenesis. Primary food sources in Western diets are the nut skin for phytol and lipids in dairy, beef and fish for its metabolites. Phytol and its metabolites gained interest as dietary compounds for cancer prevention because, as natural ligands of peroxisome proliferator-activated receptor-α and -γ and retinoid X receptor, phytol and its metabolites have provided some evidence in cell culture studies and limited evidence in animal models of anti-carcinogenic, anti-inflammatory and anti-metabolic-syndrome properties at physiological concentrations. However, there may be a narrow range of efficacy, because phytol and its metabolites at supra-physiological concentrations can cause in vitro cytotoxicity in non-cancer cells and can cause morbidity and mortality in animal models. In human studies, evidence for a role of phytol and its metabolites in cancer prevention is currently limited and inconclusive. In short, phytol and its metabolites are potential dietary compounds for cancer prevention, assuming the challenges in preventing cytotoxicity in non-cancer cells and animal models and understanding phytol metabolism can be mitigated.

Peroxisomes and cancer: The role of a metabolic specialist in a disease of aberrant metabolism

Cancer is irrevocably linked to aberrant metabolic processes. While once considered a vestigial organelle, we now know that peroxisomes play a central role in the metabolism of reactive oxygen species, bile acids, ether phospholipids (e.g. plasmalogens), very-long chain, and branched-chain fatty acids. Immune system evasion is a hallmark of cancer, and peroxisomes have an emerging role in the regulation of cellular immune responses. Investigations of individual peroxisome proteins and metabolites support their pro-tumorigenic functions. However, a significant knowledge gap remains regarding how individual functions of proteins and metabolites of the peroxisome orchestrate its potential role as a pro-tumorigenic organelle. This review highlights new advances in our understanding of biogenesis, enzymatic functions, and autophagic degradation of peroxisomes (pexophagy), and provides evidence linking these activities to tumorigenesis. Finally, we propose avenues that may be exploited to target peroxisome-related processes as a mode of combatting cancer.

Metabolomics-A Promising Approach to Pituitary Adenomas

Background: Metabolomics-the novel science that evaluates the multitude of low-molecular-weight metabolites in a biological system, provides new data on pathogenic mechanisms of diseases, including endocrine tumors. Although development of metabolomic profiling in pituitary disorders is at an early stage, it seems to be a promising approach in the near future in identifying specific disease biomarkers and understanding cellular signaling networks. Objectives: To review the metabolomic profile and the contributions of metabolomics in pituitary adenomas (PA). Methods: A systematic review was conducted via PubMed, Web of Science Core Collection and Scopus databases, summarizing studies that have described metabolomic aspects of PA. Results: Liquid chromatography tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) spectrometry, which are traditional techniques employed in metabolomics, suggest amino acids metabolism appears to be primarily altered in PA. N-acetyl aspartate, choline-containing compounds and creatine appear as highly effective in differentiating PA from healthy tissue. Deoxycholic and 4-pyridoxic acids, 3-methyladipate, short chain fatty acids and glucose-6-phosphate unveil metabolite biomarkers in patients with Cushing's disease. Phosphoethanolamine, N-acetyl aspartate and myo-inositol are down regulated in prolactinoma, whereas aspartate, glutamate and glutamine are up regulated. Phosphoethanolamine, taurine, alanine, choline-containing compounds, homocysteine, and methionine were up regulated in unclassified PA across studies. Intraoperative use of ultra high mass resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which allows localization and delineation between functional PA and healthy pituitary tissue, may contribute to achievement of complete tumor resection in addition to preservation of pituitary cell lines and vasopressin secretory cells, thus avoiding postoperative diabetes insipidus. Conclusion: Implementation of ultra high performance metabolomics analysis techniques in the study of PA will significantly improve diagnosis and, potentially, the therapeutic approach, by identifying highly specific disease biomarkers in addition to novel molecular pathogenic mechanisms. Ultra high mass resolution MALDI-MSI emerges as a helpful clinical tool in the neurosurgical treatment of pituitary tumors. Therefore, metabolomics appears to be a science with a promising prospect in the sphere of PA, and a starting point in pituitary care.

A review and meta-analysis of prospective studies of red and processed meat, meat cooking methods, heme iron, heterocyclic amines and prostate cancer

Prostate cancer remains a significant public health concern among men in the U.S. and worldwide. Epidemiologic studies have generally produced inconclusive results for dietary risk factors for prostate cancer, including consumption of red and processed meats. We aimed to update a previous meta-analysis of prospective cohorts of red and processed meats and prostate cancer with the inclusion of new and updated cohort studies, as well as evaluate meat cooking methods, heme iron, and heterocyclic amine (HCA) intake exposure data. A comprehensive literature search was performed and 26 publications from 19 different cohort studies were included. Random effects models were used to calculate summary relative risk estimates (SRREs) for high vs. low exposure categories. Additionally, meta-regression analyses and stratified intake analyses were conducted to evaluate dose-response relationships. The SRREs for total prostate cancer and total red meat consumption, fresh red meat consumption, and processed meat consumption were 1.02 (95% CI: 0.92-1.12), 1.06 (95% CI: 0.97-1.16), and 1.05 (95% CI: 1.01-1.10), respectively. Analyses were also conducted for the outcomes of non-advanced, advanced, and fatal prostate cancer when sufficient data were available, but these analyses did not produce significant results. No significant SRREs were observed for any of the meat cooking methods, HCA, or heme iron analyses. Dose-response analyses did not reveal significant patterns of associations between red or processed meat and prostate cancer. In conclusion, the results from our analyses do not support an association between red meat or processed consumption and prostate cancer, although we observed a weak positive summary estimate for processed meats.

Calcium intake, polymorphisms of the calcium-sensing receptor, and recurrent/aggressive prostate cancer

PURPOSE

To assess whether calcium intake and common genetic variants of the calcium-sensing receptor (CASR) are associated with either aggressive prostate cancer (PCa) or disease recurrence after prostatectomy.

METHODS

Calcium intake at diagnosis was assessed, and 65 common single-nucleotide polymorphisms (SNPs) in CASR were genotyped in 886 prostatectomy patients. We investigated the association between calcium intake and CASR variants with both PCa recurrence and aggressiveness (defined as Gleason score ≥4 + 3, stage ≥pT3, or nodal-positive disease).

RESULTS

A total of 285 men had aggressive disease and 91 experienced recurrence. A U-shaped relationship between calcium intake and both disease recurrence and aggressiveness was observed. Compared to the middle quintile, the HR for disease recurrence was 3.07 (95% CI 1.41-6.69) for the lowest quintile and 3.21 (95% CI 1.47-7.00) and 2.97 (95% CI 1.37-6.45) for the two upper quintiles, respectively. Compared to the middle quintile, the OR for aggressive disease was 1.80 (95% CI 1.11-2.91) for the lowest quintile and 1.75 (95% CI 1.08-2.85) for the highest quintile of calcium intake. The main effects of CASR variants were not associated with PCa recurrence or aggressiveness. In the subgroup of patients with moderate calcium intake, 31 SNPs in four distinct blocks of high linkage disequilibrium were associated with PCa recurrence.

CONCLUSIONS

We observed a protective effect of moderate calcium intake for PCa aggressiveness and recurrence. While CASR variants were not associated with these outcomes in the entire cohort, they may be associated with disease recurrence in men with moderate calcium intakes.

Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies

BACKGROUND

Dairy product and calcium intakes have been associated with increased prostate cancer risk, but whether specific dairy products or calcium sources are associated with risk is unclear.

OBJECTIVE

In the Continuous Update Project, we conducted a meta-analysis of prospective studies on intakes of dairy products and calcium and prostate cancer risk.

DESIGN

PubMed and several other databases were searched up to April 2013. Summary RRs were estimated by using a random-effects model.

RESULTS

Thirty-two studies were included. Intakes of total dairy products [summary RR: 1.07 (95% CI: 1.02, 1.12; n = 15) per 400 g/d], total milk [summary RR: 1.03 (95% CI: 1.00, 1.07; n = 14) per 200 g/d], low-fat milk [summary RR: 1.06 (95% CI: 1.01, 1.11; n = 6) per 200 g/d], cheese [summary RR: 1.09 (95% CI: 1.02, 1.18; n = 11) per 50 g/d], and dietary calcium [summary RR: 1.05 (95% CI: 1.02, 1.09; n = 15) per 400 mg/d] were associated with increased total prostate cancer risk. Total calcium and dairy calcium intakes, but not nondairy calcium or supplemental calcium intakes, were also positively associated with total prostate cancer risk. Supplemental calcium was associated with increased risk of fatal prostate cancer.

CONCLUSIONS

High intakes of dairy products, milk, low-fat milk, cheese, and total, dietary, and dairy calcium, but not supplemental or nondairy calcium, may increase total prostate cancer risk. The diverging results for types of dairy products and sources of calcium suggest that other components of dairy rather than fat and calcium may increase prostate cancer risk. Any additional studies should report detailed results for subtypes of prostate cancer.

Serum phytanic and pristanic acid levels and prostate cancer risk in Finnish smokers

Phytanic acid is a saturated branched-chain fatty acid found predominantly in red meat and dairy products, and may contribute to the elevated risks of prostate cancer associated with higher consumption of these foods. Pristanic acid is formed during peroxisomal oxidation of phytanic acid, and is the direct substrate of α-Methyl-CoA-Racemase (AMACR)--an enzyme that is consistently overexpressed in prostate tumors relative to benign tissue. We measured phytanic and pristanic acids as percentages of total fatty acids by gas chromatography-mass spectrometry in prediagnostic blood samples from 300 prostate cancer cases and 300 matched controls, all of whom were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study supplementation trial and follow-up cohort. In addition to providing a fasting blood sample at baseline, all men completed extensive diet, lifestyle, and medical history questionnaires. Among controls, the strongest dietary correlates of serum phytanic and pristanic acids were saturated fat, dairy fat, and butter (r = 0.50 and 0.40, 0.46 and 0.38, and 0.40 and 0.37, respectively; all P-values <0.001). There was no association between serum phytanic acid and risk of total or aggressive prostate cancer in multivariate logistic regression models (for increasing quartiles, odds ratios (OR) and 95% confidence intervals (CI) for aggressive cancer were 1.0 (referent), 1.62 (0.97-2.68), 1.12 (0.66-1.90), and 1.14 (0.67-1.94), P(trend) = 0.87). Pristanic acid was strongly correlated with phytanic acid levels (r = 0.73, P < 0.0001), and was similarly unrelated to prostate cancer risk. Significant interactions between phytanic and pristanic acids and baseline circulating β-carotene concentrations were noted in relation to total and aggressive disease among participants who did not receive β-carotene supplements as part of the original ATBC intervention trial. In summary, we observed no overall association between serum phytanic and pristanic acid levels and prostate cancer risk. Findings indicating that the direction and magnitude of these associations depended upon serum levels of the antioxidant β-carotene among men not taking β-carotene supplements should be interpreted cautiously, as they are likely due to chance.

Dietary factors and risk for advanced prostate cancer

Prostate cancer is the second most common cancer among men worldwide. Although some nutrients have been linked to the development of total prostate cancer, it remains unclear whether these nutrients modulate the risk of its clinically significant form - advanced tumor. Therefore, this study sought to perform a systematic review of the literature on this topic. The papers reviewed were identified from PubMed using keywords diet and advanced, metastatic, or lethal prostate cancer. A total of 46 papers published until September 2012 met our eligibility criteria and thus were evaluated in this review. Epidemiologic studies have shown that, overall, the habitual consumption of a diet high in saturated fat, well-done meats, and calcium is associated with an increased risk for advanced prostate cancer. An inconsistent association was observed for intake of total meat, fruits, and vegetables. Although most case-control studies suggest that intake of these nutrients or foods significantly alters advanced prostate cancer risk, cohort studies yielded mixed results. No apparent effect of fish and zinc intake on advanced prostate cancer was found in most epidemiologic studies. Epidemiologic studies conducted to date have revealed that some dietary factors modulate the risk for advanced prostate cancer. If these findings are confirmed by more adequately powered epidemiologic studies, especially prospective cohort studies that measure the nutrients and their biochemical indicators, the risk of advanced prostate cancer, which is fatal and thus clinically significant, may be reduced by dietary modification or chemoprevention.

Prostate cancer and the influence of dietary factors and supplements: a systematic review

Background

Prostate cancer is the second most common cause of cancer worldwide after lung cancer. There is increasing evidence that diet and lifestyle plays a crucial role in prostate cancer biology and tumourigenesis. Prostate cancer itself represents a good model of cancer in which to look for chemopreventive agents due to the high disease prevalence, slowly progressive nature, and long latency period. Dietary agents have gained considerable attention, often receiving much publicity in the media.

Aim

To review the key evidence available for potential chemopreventive nutrients.

Methods

The methodology for this review involved a PubMed search from 1990 to 2013 using the key-words “diet and prostate cancer”, “nutrition and prostate cancer”, “dietary factors and prostate cancer”, “prostate cancer epidemiology”, “prostate cancer prevention”, “prostate cancer progression”.

Results

Red meat, dietary fat and milk intake should be minimised as they appear to increase the risk of prostate cancer. Fruit and vegetables and polyphenols may be preventive in prostate cancer, but further studies are needed to draw more solid conclusions and to clarify their role in patients with an established diagnosis of prostate cancer. Selenium and vitamin supplements cannot be advocated for the prevention of prostate cancer and indeed higher doses may be associated with a worse prognosis. There is no specific evidence regarding benefits of probiotics or prebiotics in prostate cancer.

Conclusions

From the wealth of evidence available, many recommendations can be made although more randomised control trials are required. These need to be carefully designed due to the many confounding factors and heterogeneity of the population.

The role of an abnormal prostate-specific antigen level and an abnormal digital rectal examination in the diagnosis of prostate cancer: A cross-sectional study in Qatar

Objective

To investigate the role of an abnormal prostate-specific antigen (PSA) level and abnormal findings on a digital rectal examination (DRE) in the detection of prostate cancer in men in Qatar.

Patients and methods

Between June 2008 and September 2012, 651 patients had a transrectal ultrasonography-guided biopsy of the prostate (TRUSBP) at our centre. The indications for a biopsy were a high PSA level (>4 ng/mL), or an abnormal DRE result. Patients were assessed by a thorough history, clinical examination and routine laboratory investigations. Data, including age, DRE findings, TRUS findings, total PSA level, prostate volume and the pathology results, were evaluated.

Results

The mean (SD) age of the 651 patients was 64.1 (7.4) years. Prostate cancer was detected in 181 men (27.8%), benign prostatic hyperplasia in 275 (42.2%) and prostatitis in 236 (36.4%). The sensitivity and specificity for detecting prostate cancer were 93.9% and 8.5% for an abnormal PSA level (>4 ng/mL), 46.1% and 84.7% for abnormal DRE findings, and 95% and 30.2% for the two combined. Using a receiver operating characteristics curve, a PSA threshold of 7.9 ng/mL had a sensitivity of 56.6% and specificity of 52.8%. When a PSA threshold of 7.9 ng/mL was used in combination with abnormal DRE findings, the overall accuracy was 76.9%.

Conclusion

The PSA threshold level of 7.9 ng/mL, determined by this analysis, has a higher likelihood of detecting prostate cancer in men in Qatar. However, it failed to detect cancer in substantially many men with statistically significant disease.

Phytanic acid and the risk of non-Hodgkin lymphoma

Greater consumption of red meat, processed meat and dairy products has been associated with an increased risk of non-Hodgkin lymphoma (NHL) in several previous reports. Phytanic acid, a saturated fatty acid obtained primarily through the consumption of ruminant meat and dairy products, may offer a potential underlying mechanism for these associations. In a population-based case-control study of 336 cases and 460 controls conducted in Nebraska during 1999-2002, we examined whether phytanic acid-containing foods or total phytanic acid intake, estimated from a food frequency questionnaire and the published phytanic acid values of 151 food items, were associated with increased NHL risk. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals for overall NHL and the common NHL histologic subtypes. In multivariable models, higher intakes of density-adjusted beef [OR(T3 vs. T1) = 1.5 (1.1-2.2); P(trend) = 0.02], total dairy products [OR = 1.5 (1.1-2.2); P(trend) = 0.02) and milk [OR = 1.6 (1.1-2.3); P(trend) = 0.01] were associated with an increased risk of NHL. Intake of total phytanic acid was positively associated with NHL risk [OR = 1.5 (1.0-2.1); P(trend) = 0.04]. In analyses stratified by NHL subtype, greater consumption of beef was associated with an increased risk of diffuse large B-cell lymphoma, and greater consumption of milk was associated with an increased risk of follicular lymphoma (FL). Total phytanic acid intake was associated with an increased risk of FL and small lymphocytic lymphoma/chronic lymphocytic leukemia. Our results provide support that total phytanic acid and phytanic acid-containing foods may increase NHL risk.