Diet and prostate cancer risk in a cohort of smokers, with a specific focus on calcium and phosphorus (Finland)

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.

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.

The association between dairy products consumption and prostate cancer risk: a systematic review and meta-analysis

In this study, we conducted a meta-analysis to estimate the relationship between the consumption of dairy products and the risk of prostate cancer. We searched PubMed, Embase and Cochrane databases for relevant articles and identified a total of thirty-three cohort studies between 1989 and 2020. The qualities of included studies were assessed using Newcastle–Ottawa scale. Pooled adjusted relative risks (RR) with 95 % CI were calculated. We performed subgroup analyses stratified by dairy type, prostate cancer type, follow-up years, treatment era, collection times, adjustment for confounders and geographic location. In the subgroup analysis stratified by prostate cancer type, the pooled RR were 0·98 (95 % CI 0·94, 1·03) in the advanced group, 1·10 (95 % CI 0·98, 1·24) in the non-advanced group and 0·92 (95 % CI 0·84, 1·00) in the fatal group. In the dose–response analysis, a positive association for the risk of prostate cancer was observed for total dairy products 400 g/d (RR: 1·02; 95 % CI 1·00, 1·03), total milk 200 g/d (RR: 1·02; 95 % CI 1·01, 1·03), cheese 40 g/d (RR: 1·01; 95 % CI 1·00, 1·03) and butter 50 g/d (RR: 1·03; 95 % CI 1·01, 1·05). A decreased risk was observed for the intake of whole milk 100 g/d (RR: 0·97; 95 % CI 0·96, 0·99). Our meta-analysis suggests that high intakes of dairy products may be associated with an increased risk of prostate cancer; however, since many of the studies were affected by prostate-specific antigen (PSA) screening bias, additional studies with an adjustment of PSA screening are needed.

Dietary protein intake and prostate cancer risk in adults: A systematic review and dose-response meta-analysis of prospective cohort studies

OBJECTIVE

This study aimed to conduct a comprehensive systematic review and dose-response meta-analysis to summarize available findings on the associations between dietary protein intake and prostate cancer risk as well as the dose-response associations of total, animal, plant, and dairy protein intake with prostate cancer risk.

METHODS

This study followed the 2020 PRISMA guideline. We conducted a systematic search in the online databases of PubMed, Scopus, ISI Web of Science, and Google Scholar to detect eligible prospective studies published to October 2021 that assessed total, animal, plant, and dairy protein intake in relation to prostate cancer risk.

RESULTS

Overall, 12 articles containing prospective studies with a total sample size of 388,062 individuals and 30,165 cases of prostate cancer were included. The overall relative risks (RRs) of prostate cancer, comparing the highest and lowest intakes of total, animal, plant, and dairy protein intake, were 0.99 (95% CI: 92-1.07, I² =12.8%), 0.99 (95% CI: 95-1.04, I² =0), 1.01 (95% CI: 96-1.06, I² =0), and 1.08 (95% CI: 1.00-1.16, I² =38.1%), respectively, indicating a significant positive association for dairy protein intake (P = 0.04) and non-significant associations for other protein types. However, this positive association was seen among men who consumed ≥ 30 gr/day of dairy protein, such that a 20 g/d increase in dairy protein intake (equal to 2.5 cups milk or yogurt) was associated with a 10% higher risk of prostate cancer (Pooled RR: 1.10, 95% CI: 1.02-1.20, I² = 42.5%). Such dose-response association was not seen for total, animal, and plant protein intake.

CONCLUSION

Overall, dairy protein intake may increase the risk of prostate cancer in men who consumed > 30 gr/day of dairy protein. Larger, well-designed studies are still required to further evaluation of this association.

Minerals and Cancer: Overview of the Possible Diagnostic Value

Simple Summary

Minerals are important but often overlooked compounds that are required for a variety of cellular biochemical processes and pathways that regulate cell proliferation. Their dietary imbalance, which is becoming more common in the diets of industrialized countries, is linked to an increased risk of cancer. The current review will present some of the most important minerals for human physiology and evaluate their potential application as cancer biomarkers.

Abstract

Cancer is the second leading cause of death worldwide and is expected to increase by one-third over the next two decades, in parallel with the growing proportion of the elderly population. Treatment and control of cancer incidence is a global issue. Since there is no clear way to prevent or cure this deadly malignancy, diagnostic, predictive, and prognostic markers for oncological diseases are of great therapeutic value. Minerals and trace elements are important micronutrients for normal physiological function of the body. They are abundant in natural food sources and are regularly included in dietary supplements whereas highly processed industrial food often contains reduced or altered amounts of them. In modern society, the daily intake, storage pools, and homeostasis of these micronutrients are dependent on certain dietary habits and can be thrown out of balance by malignancies. The current work summarizes the data on minerals and trace elements associated with abnormal accumulation or depletion states in tumor patients and discusses their value as potential tumor-associated biomarkers that could be introduced into cancer therapy.

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.

Fruit and Vegetable Consumption and the Risk of Prostate Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Emerging researches has evaluated whether fruit and vegetable consumption reduce the risk of prostate cancer. However, the conclusions of published articles remained confusing. Thus, we conducted an updated systematic review and meta-analysis to confirm the relationship of fruit and vegetable consumption and the risk of prostate cancer.

METHOD

We searched PubMed, EMBASE, Web of Science and Chinese National Knowledge Infrastructure (CNKI) up to September 1, 2020. We finally included 17 cohort studies related to fruit or vegetable intake after rigid quality assessment and checking references of the retrieved articles and relevant reviews. Newcastle-Ottawa scale was adopted to assess the quality of studies and random effect model with RR and 95% CI were used to assess the risk.

RESULTS

No significant relationship was found between fruit consumption (RR = 1.00, 95% CI = 0.94-1.05) and vegetable consumption (RR = 0.98, 95% CI = 0.94-1.02) and the risk of prostate cancer. No significant heterogeneity or publication bias was identified.

CONCLUSION

Our updated meta-analysis demonstrated that fruit and vegetable consumption can barely reduce the risk of prostate cancer with several limitations. Further clinical and basic researches are eagerly awaited to confirm our results and clarify the potential biological mechanisms.

Dietary energy density and risk of prostate cancer: (A case-control study)

OBJECTIVE

Some observational studies investigated the association between dietary energy density (DED) and risk of cancers with inconstant results. In addition, there is no study on such association among patients with prostate cancer (PC). The present study was performed to evaluate the association between dietary energy density (DED) and PC risk.

METHODS

In this case-control study, one hundred and twenty-five participants were enrolled (62 cases and 63 controls). Dietary intakes were assessed using 160-item semi-quantitative food frequency questionnaire. In addition, demographic characteristics were collected using a general questionnaire and anthropometric indices were measured based on the available guidelines. The association between DED and PC risk was evaluated using multivariable logistic regression.

RESULTS

The results showed that higher DED score was associated with increased risk of PC (OR = 2.59; 95% CI= (1.24-5.40)). Interestingly, after adjusting for potential confounders ((smoking, physical activity, energy intake, education, ethnicity, job, anti-hyperlipidemic drugs, antihypertensive drugs, and aspirin) the results remained significant (OR = 2.87; 95% CI= (1.17-7.05)).

CONCLUSION

Our findings suggest that DED may increase the risk of PC. However, more prospective studies are warranted to confirm these results.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

The Epidemiology of Prostate Cancer

Prostate cancer is a major cause of disease and mortality among men, and each year 1.6 million men are diagnosed with and 366,000 men die of prostate cancer. In this review, we discuss the state of evidence for specific genetic, lifestyle, and dietary factors associated with prostate cancer risk. Given the biological heterogeneity of this cancer, we focus on risk factors for advanced or fatal prostate cancer. First, we provide descriptive epidemiology statistics and patterns for prostate cancer incidence and mortality around the world. This includes discussion of the impact of prostate-specific antigen screening on prostate cancer epidemiology. Next, we summarize evidence for selected risk factors for which there is strong or probable evidence of an association: genetics, obesity and weight change, physical activity, smoking, lycopene and tomatoes, fish, vitamin D and calcium, and statins. Finally, we highlight future directions for prostate cancer epidemiology research.

Association between dietary protein intake and prostate cancer risk: evidence from a meta-analysis

Background

Many studies were conducted to explore the relationship between dietary protein intake and risk of prostate cancer, obtaining inconsistent results. Therefore, this study aims to comprehensively explore the predicted role of dietary protein intake for risk of prostate cancer.

Methods

Databases of Web of Knowledge, PubMed, Chinese National Knowledge Infrastructure (CNKI), and Wan Fang Med Online were searched up to August 30, 2017. Eligible studies were included based on our definite inclusion criteria. Summarized relative risk (RR) and corresponding 95% confidence interval (CI) were pooled with a random effects model. Sensitive analysis and publication bias were performed.

Results

At the end, a total of 12 articles comprising 13,483 prostate cancer cases and 286,245 participants were included. The summary RR and 95%CI of the highest protein intake compared to those with the lowest protein intake on prostate cancer risk were 0.993 (95%CI = 0.930–1.061), with no between-study heterogeneity found (I² = 0.0%, P = 0.656). Moreover, the association was not significant on prostate cancer risk with animal protein intake [RR = 1.001, 95%CI = 0.917–1.092] or vegetable protein intake [RR = 0.986, 95%CI = 0.904–1.076]. The results were not changed when we conducted subgroup analysis by study design, cancer type, or geographic locations. We did not detect any publication bias using Egger’s test (P = 0.296) and funnel plot.

Conclusion

Our study concluded that protein intake may be not associated on prostate cancer.

Carbohydrate intake and the risk of prostate cancer

BACKGROUND

Prostate cancer (PCa) is one of the leading cause cancer among men worldwide. Many epidemiologic studies have reported an association between carbohydrate intake and PCa. However, the evidence from epidemiologic studies is inconsistent. We conducted a comprehensive meta-analysis to explore the associations between carbohydrate intake and PCa risk and to investigate potential dose-response relationships.

METHODS

We searched PubMed and EMBASE for studies published from 1980 to 2018. 21 studies were included with 98,739 participants and 11,573 cases. Multivariate-adjusted odds ratios (ORs) were pooled using random-effect models. Potential dose-response relationships were evaluated for PCa risk.

RESULTS

We did not detect an association about higher carbohydrate intake and PCa risk (OR:1.11, 95% confidence interval [CI]: 0.98-1. 26, I² = 62.7%), nor association was detected about higher carbohydrate intake with advanced PCa risk (OR:0.95, 95% CI: 0.78-1.16, I² = 14.1%) or non-advanced Pca risk (OR:1.01, 95% CI: 0.79-1.29, I² = 64.4%). There was not a significant dose-response association observed for carbohydrate intake with PCa risk and advanced PCa risk.

CONCLUSIONS

Our meta-analysis shows no association between carbohydrate intake and prostate cancer risk. Nor is association detected about carbohydrate intake with advanced or non-advanced Pca risk. More studies are needed for a further dose-response meta-analysis.

Anticancer potential of dietary vitamin D and ascorbic acid: A review

Cancers have been the leading cause of death worldwide and poor diet and physical inactivity are major risk factors in cancer-related deaths. Micronutrients such as vitamins and minerals appear to have preventive properties against cancer. One important mechanism by which dietary changes can exert preventive effects on cancer is via the modulation of micronutrient concentrations in target tissues. Many of these micronutrients are available in the form of dietary supplements, and the intake of these supplements is prevalent in various parts of the world. However, in most cases, it is not known which micronutrient (or combination of micronutrients) is best when it comes to lowering the risk of cancer. The present review illustrates the effect of vitamin D and ascorbic acid intake on preventing cancer.

Dietary Food-Additive Phosphate and Human Health Outcomes

Dietary intake of phosphorus is required for human health, and dietary reference intakes for phosphorus have been established. Food-grade phosphates are used as additives to provide a wide range of technical functions in food production. Phosphates are often the most efficient ingredients to provide the required functionality in many applications, and in some cases, there are not effective and approved alternatives. However, many investigators have expressed concern about the quantities of phosphorus and food-additive phosphate present in the diets of many populations. This paper presents the outcome of an extensive review of 110 primary research articles focused on identifying evidence that substantiates or refutes associations of total dietary phosphorus and food-additive phosphate intake with health and disease in humans. The lack of conclusive evidence prevented the drawing of firm conclusions about the safety and possible risks of food-additive phosphate in the general population, which is consonant with the overall assessments of authoritative institutions who have concluded that available data are insufficient to make the required determinations. Despite the inadequacy of the evidence currently available, many of the authors of the publications reviewed for this paper expressed concerns about the quantities of phosphorus and food-additive phosphate in the diets of the populations and subpopulations they studied. At the same time, most of these authors offered only qualified conclusions and expressed themselves tentatively. In addition, authors of primary research publications, authors of review articles, and authoritative institutions have called for the conduct of further research.

Associations between unprocessed red and processed meat, poultry, seafood and egg intake and the risk of prostate cancer: A pooled analysis of 15 prospective cohort studies

Reports relating meat intake to prostate cancer risk are inconsistent. Associations between these dietary factors and prostate cancer were examined in a consortium of 15 cohort studies. During follow-up, 52,683 incident prostate cancer cases, including 4,924 advanced cases, were identified among 842,149 men. Cox proportional hazard models were used to calculate study-specific relative risks (RR) and then pooled using random effects models. Results do not support a substantial effect of total red, unprocessed red and processed meat for all prostate cancer outcomes, except for a modest positive association for tumors identified as advanced stage at diagnosis (advanced(r)). For seafood, no substantial effect was observed for prostate cancer regardless of stage or grade. Poultry intake was inversely associated with risk of advanced and fatal cancers (pooled multivariable RR [MVRR], 95% confidence interval, comparing ≥ 45 vs. <5 g/day: advanced 0.83, 0.70-0.99; trend test p value 0.29), fatal, 0.69, 0.59-0.82, trend test p value 0.16). Participants who ate ≥ 25 versus <5 g/day of eggs (1 egg ∼ 50 g) had a significant 14% increased risk of advanced and fatal cancers (advanced 1.14, 1.01-1.28, trend test p value 0.01; fatal 1.14, 1.00-1.30, trend test p value 0.01). When associations were analyzed separately by geographical region (North America vs. other continents), positive associations between unprocessed red meat and egg intake, and inverse associations between poultry intake and advanced, advanced(r) and fatal cancers were limited to North American studies. However, differences were only statistically significant for eggs. Observed differences in associations by geographical region warrant further investigation.

Dietary fiber, whole grains, carbohydrate, glycemic index, and glycemic load in relation to risk of prostate cancer

BACKGROUND

The relationships between dietary fiber, whole grains, carbohydrate, glycemic index (GI), glycemic load (GL), and prostate cancer risk are unclear. We conducted a systematic review and meta-analysis to investigate these associations.

METHODS

Relevant studies were identified by a search of PubMed database and EMBASE database up to April 2015. A random effects model was used to calculate the summary relative risks (RRs) and their corresponding 95% confidence intervals (CIs).

RESULTS

Twenty-seven epidemiological studies (18 case-control studies and nine cohort studies) were included in the final analysis. The pooled RRs of prostate cancer were 0.94 (95% CI 0.85-1.05, P=0.285), 1.13 (95% CI 0.98-1.30, P=0.095), 0.96 (95% CI 0.81-1.14, P=0.672), 1.06 (95% CI 0.96-1.18, P=0.254), and 1.04 (95% CI 0.91-1.18, P=0.590) for dietary fiber, whole grains, carbohydrate, GI, and GL, respectively. There was no evidence of significant publication bias based on the Begg's test and Egger's test.

CONCLUSION

The findings of this meta-analysis indicate that, based on available information, dietary fiber, whole grains, carbohydrate, GI, and GL are not associated with the risk of prostate cancer.

Fat Intake Is Not Linked to Prostate Cancer: A Systematic Review and Dose-Response Meta-Analysis

Background

Since the late 1960s, the average global supply of fat has increased by 20 g per capita per day. While fat intake has been considered a potential risk factor for prostate cancer (Pca), the hypothesis from previous epidemiologic studies remained equivocal.

Materials and Methods

Relevant cohort studies were identified through a literature search in PubMed, ScienceDirect and Wiley Online Library up to March 1, 2015. A systematic review and dose-response meta-analysis were used to assess the relationship between fat intake and the risk for Pca.

Results

We identified 14 cohort studies, which included 37,349 cases and a total of 751,030 participants. We found no evidence of a non-linear association between fat intake and the risk for Pca. Overall, the summarized relative risks for every 28.35 g increment a day was 0.99 (95%CI: 0.98, 1.01; P=0.94; n=13) for total fat intake, 1.00 (95%CI: 1.00, 1.00; P=0.72; n=9) for saturated fat, 0.99 (95%CI: 0.95, 1.03; P=0.55; n=7) for polyunsaturated fat, and 1.00 (95%CI: 0.95, 1.04; P=0.85; n=8) for monounsaturated fat. Additionally, there was no link to the risk for advanced stage Pca regarding total fat intake (RR=1.02, 95%CI: 0.96, 1.08; P=0.63; n=5), saturated fat (RR=0.96, 95%CI: 0.84, 1.11; P=0.61; n=6), polyunsaturated fat (RR=0.96, 95%CI: 0.79, 1.17; P=0.68; n=6), or monounsaturated fat (RR=0.96, 95%CI: 0.86, 1.07; P=0.42; n=6). Subgroup and sensitively analyses showed consistent results.

Conclusion

Little evidence from published cohort studies supports the statement that total fat, saturated fat or unsaturated fat intake increases the risk for Pca or advanced stage Pca.

Dietary carbohydrate and prostate cancer risk: a meta-analysis

Carbohydrate intake has been inconsistently associated with risk of prostate cancer. We review and quantitatively summarize the evidence from observational studies in a meta-analysis. We searched the PubMed database for observational studies related to the association of carbohydrate intake and prostate cancer risk up to December 25, 2013. Summary relative risks (RRs) were estimated by the use of a random effects model. We included 13 case-control studies with 4,367 cases and 6,205 controls, and 5 cohort studies with 3,679 cases and 74,115 participants in this meta-analysis. The summary RR of prostate cancer for the highest vs. the lowest carbohydrate intake was 1.06 [95% confidence interval (CI): 0.93-1.20, I(2) = 46.8%] for all included studies. In the subgroup analyses stratified by study design, the summary RRs for the highest vs. the lowest carbohydrate intake were 1.04 (95% CI: 0.87-1.23) for case-control studies and 1.06 (95% CI: 0.88-1.28) for cohort studies. For the 5 studies that reported results for advanced prostate cancer, the summary RR was 0.92 (95% CI: 0.71-1.20). This meta-analysis of observational studies indicates that there is no association between carbohydrate intake and prostate cancer risk. Further studies are needed to confirm our findings.

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.

Fruit and vegetable intake and prostate cancer risk: a meta-analysis

AIMS

Recent reports have examined the effect of fruit and vegetable intake on the risk of prostate cancer, but the results are inconsistent. A meta-analysis of prospective studies was conducted to arrive at quantitative conclusions about the contribution of vegetable and fruit intake to the incidence of prostate cancer.

METHODS

A comprehensive, systematic search of medical literature published up to June 2012 was performed to identify relevant studies. Separate meta-analyses were conducted for fruit and vegetable consumption. The presence of publication bias was assessed using Egger and Begg tests.

RESULTS

In total, 16 cohort studies met the inclusion criteria and were included in the meta-analysis. The combined adjusted relative risk comparing highest with lowest categories showed that there was no association between vegetable and fruit consumption and prostate cancer incidence. The pooled relative risk was 0.97 (95%CI 0.93, 1.01) for vegetables and 1.02 (95%CI 0.98, 1.07) for fruit. There is no heterogeneity between the studies. No publication bias was detected.

CONCLUSION

This meta-analysis suggests that total fruit or vegetable consumption may not exert a protective role in the risk of prostate cancer.

Insulin-like growth factor pathway genes and blood concentrations, dietary protein and risk of prostate cancer in the NCI Breast and Prostate Cancer Cohort Consortium (BPC3)

It has been hypothesized that a high intake of dairy protein may increase prostate cancer risk by increasing the production of insulin-like growth factor 1 (IGF-1). Several single nucleotide polymorphisms (SNPs) have been weakly associated with circulating concentrations of IGF-1 and IGF binding protein 3 (IGFBP-3), but none of these SNPs was associated with risk of prostate cancer. We examined whether an association between 16 SNPs associated with circulating IGF-1 or IGFBP-3 concentrations and prostate cancer exists within subgroups defined by dietary protein intake in 5,253 cases and 4,963 controls of European ancestry within the NCI Breast and Prostate Cancer Cohort Consortium (BPC3). The BPC3 includes nested case-control studies within large North-American and European cohorts. Per-allele odds ratios for prostate cancer for the SNPs were compared across tertiles of protein intake, which was expressed as the percentage of energy derived from total, animal, dairy or plant protein sources, using conditional logistic regression models. Total, animal, dairy and plant protein intakes were significantly positively associated with blood IGF-1 (p < 0.01), but not with IGFBP-3 concentrations (p > 0.10) or with risk of prostate cancer (p > 0.20). After adjusting for multiple testing, the SNP-prostate cancer associations did not differ by intakes of protein, although two interactions by intake of plant protein were of marginal statistical significance [SSTR5 (somatostatin receptor 5)-rs197056 (uncorrected p for interaction, 0.001); SSTR5-rs197057 (uncorrected p for interaction, 0.002)]. We found no strong evidence that the associations between 16 IGF pathway SNPs and prostate cancer differed by intakes of dietary protein.

Intake of vitamins D and A and calcium and risk of non-Hodgkin lymphoma: San Francisco Bay Area population-based case-control study

Several nutrients identified as potentially cancer protective have been inconsistently associated with non-Hodgkin lymphoma (NHL) risk. Dietary history data, including use of vitamin supplements, were collected using a semiquantitative food frequency questionnaire administered during in-person interviews with 4,133 participants (2,052 cases, 2,081 controls) in a San Francisco Bay Area population-based case-control study. Data were used to determine the association of intake levels of vitamins D and A and calcium with risk of NHL and NHL subtypes. Odds ratios (OR) and 95% confidence intervals (CI) were computed as estimates of relative risk using adjusted unconditional logistic regression. Increasing vitamin D intake from food and supplements was positively associated with NHL risk in men (5th quintile: OR = 1.6, 95% CI = 1.0-2.4, P(trend) = 0.07) and with diffuse large B-cell lymphoma (DLBCL) in women and men (5th quintile: OR = 1.6, 95% CI = 1.0-2.5, P(trend) = 0.02); that was largely due to the effect in men (P(trend) = 0.03). These results do not support a strong role for vitamin D intake with NHL risk, with the exception of a potential association for DLBCL risk in men. Our results should be interpreted conservatively until further investigation in larger pooled studies can be conducted to better assess the role of vitamin D intake in lymphomagenesis.

Lifestyle and dietary factors in the prevention of lethal prostate cancer

The prevention of lethal prostate cancer is a critical public health challenge that would improve health and reduce suffering from this disease. In this review, we discuss the evidence surrounding specific lifestyle and dietary factors in the prevention of lethal prostate cancer. We present a summary of evidence for the following selected behavioral risk factors: obesity and weight change, physical activity, smoking, antioxidant intake, vitamin D and calcium, and coffee intake.

Extraskeletal benefits and risks of calcium, vitamin D and anti-osteoporosis medications

Drugs used for the prevention and the treatment of osteoporosis exert various favourable and unfavourable extra-skeletal effects whose importance is increasingly recognized notably for treatment selection.

INTRODUCTION

The therapeutic armamentarium for the prevention and the treatment of osteoporosis is increasingly large, and possible extra-skeletal effects of available drugs could influence the choice of a particular compound.

METHODS

The present document is the result of a national consensus, based on a systematic and critical review of the literature.

RESULTS

Observational research has suggested an inverse relationship between calcium intake and cardiovascular diseases, notably through an effect on blood pressure, but recent data suggest a possible deleterious effect of calcium supplements on cardiovascular risk. Many diverse studies have implicated vitamin D in the pathogenesis of clinically important non-skeletal functions or diseases, especially muscle function, cardiovascular disease, autoimmune diseases and common cancers. The possible effects of oral or intravenous bisphosphonates are well-known. They have been associated with an increased risk of oesophageal cancer or atrial fibrillation, but large-scale studies have not found any association with bisphosphonate use. Selective oestrogen receptor modulators have demonstrated favourable or unfavourable extra-skeletal effects that vary between compounds. Strontium ranelate has a limited number of non-skeletal effects. A reported increase in the risk of venous thromboembolism is not found in observational studies, and very rare cases of cutaneous hypersensitivity reactions have been reported. Denosumab has been introduced recently, and its extra-skeletal effects still have to be assessed.

CONCLUSION

Several non-skeletal effects of bone drugs are well demonstrated and influence treatment choices.

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

Phytanic acid is a saturated fatty acid found predominantly in red meat and dairy products and may contribute to increases in prostate cancer risk that are observed with higher intakes of these foods. We constructed a novel summary measure of phytanic acid intake and prospectively examined its association with prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study--a cohort of Finnish male smokers aged 50-69 years. Diet was assessed at baseline in 27,111 participants using a validated 276-item dietary questionnaire. Since phytanic acid is not currently included in food composition tables, we used the published phytanic acid content of 151 major food items to estimate total daily intake. During up to 21 years of follow-up, a total of 1,929 incident prostate cancer cases (including 438 advanced cases) were identified. Higher phytanic acid intake, though unrelated to the risk of localized disease [relative risks (RR) and 95% confidence intervals (CI) for increasing quartiles of intake = 1.00 (ref), 0.83 (0.68-1.01), 0.76 (0.62-0.94) and 0.91 (0.74-1.13); p trend = 0.23], was associated with increased risks of advanced prostate cancer [RR and 95% CI = 1.00 (ref), 1.43 (1.09-1.89), 1.31 (0.99-1.75) and 1.38 (1.02-1.89); p trend = 0.06]. This association appeared to be driven predominantly by phytanic acid obtained from dairy products (particularly butter). Our study indicates that phytanic acid may contribute to previously observed associations between high-fat animal foods (particularly dairy products) and prostate cancer risk, although some caution is warranted as it may be acting as a surrogate marker of dairy fat.

Lycopene for the prevention of prostate cancer

BACKGROUND

Prostate cancer is a common cause of death in developed countries, yet the benefits of screening for prostate cancer still remain controversial. A prostate-specific antigen (PSA) test result greater than 4 ng/mL (nanograms/millilitre) has commonly been used as the cut-off level for seeking further tests to diagnose the presence (or absence) of prostate cancer. An increase in PSA levels may not necessarily be associated with an increased risk of prostate cancer, as PSA levels may also be increased in men with benign prostatic hyperplasia and prostatitis. Despite the uncertainty of the net benefit of early detection and treatment, safe and effective methods to prevent prostate cancer are of value. Consumers, seeking greater involvement in their healthcare, are increasingly turning to lifestyle modification and complementary and alternative medicines (CAMs) to maintain their health and prevent disease. Lycopene is a member of the carotenoid family, which is found abundantly in tomatoes, tomato-based products, strawberries, and watermelon. It has been hypothesised that lycopene is a strong antioxidant, which may lower the risk of cancer (including prostate cancer) in people who have diets rich in lycopene.

OBJECTIVES

To determine whether lycopene reduces the incidence of prostate cancer and prostate cancer-specific mortality. Secondary objectives include changes in PSA levels, prostate symptoms and the nature of adverse events associated with lycopene use.

SEARCH METHODS

Electronic searches were conducted across MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) databases. No language or other limitations were imposed.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that investigated the use of lycopene for the prevention of prostate cancer were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

A search of electronic databases, performed in August 2011, identified 64 citations. All articles were selected for full-text review. From these citations, three studies were identified as meeting the inclusion criteria. Handsearching did not provide any additional studies.

MAIN RESULTS

Three RCTs, with a total of 154 participants were included in this review. None of the studies reported data on prostate cancer mortality. All of the included studies differed with respect to design, participants included and allocation of lycopene. This clinical heterogeneity limits the value on the pooled estimated of the meta-analyses. The methodological quality of two of the three included studies was assessed as posing a 'high' risk of bias. Meta-analysis indicated no statistical difference in PSA levels between men randomised to receive lycopene and the comparison group (MD (mean difference) -0.34, 95% CI (confidence interval) -2.01, 1.32). Only one study reported incidence of prostate cancer (10% in the lycopene group versus 30% in control group). The level of lycopene was also not statistically different in men randomised to receive lycopene and the comparison group (MD 0.39 µg/mL (micrograms/millilitre), 95% CI -0.19, 0.98). No other meta-analyses were possible since other outcomes assessed only had one study contributing data.

AUTHORS' CONCLUSIONS

Given that only three RCTs were included in this systematic review, and the high risk of bias in two of the three studies, there is insufficient evidence to either support, or refute, the use of lycopene for the prevention of prostate cancer. Similarly, there is no robust evidence from RCTs to identify the impact of lycopene consumption upon the incidence of prostate cancer, prostate symptoms, PSA levels or adverse events.

Dairy intake and 1,25-dihydroxyvitamin D levels in men at high risk for prostate cancer

OBJECTIVE

Dairy food intake has been associated with prostate cancer in previous work, but the mechanism by which this occurs is unknown. Dairy calcium may suppress circulating levels of potentially cancer-protective 1,25-hydroxyvitamin D (1,25(OH)2D). We examined the associations of dairy, milk, calcium, and vitamin D intake with plasma 1,25(OH)2D levels among 296 men (194 black, 102 non-black) enrolled in a high risk program for prostate cancer from 10/96 to 10/07.

METHODS

All participants completed diet and health history questionnaires and provided plasma samples, which were assessed for levels of 25-hydroxyvitamin D and 1,25(OH)2D. We used multivariate linear regression to examine associations with 1,25(OH)2D.

RESULTS

After adjustment for age, race, energy intake, BMI, and alcohol intake, we observed no associations for any of our variables of interest with 1,25(OH)2D, or any meaningful differences in estimates by race or vitamin D status.

CONCLUSION

Our findings, in a sample including a large proportion of black participants, do not confirm previous findings showing an inverse association between calcium intake and 1,25(OH)2D levels. As such, they suggest that future work should explore other mechanisms by which dairy foods and calcium might increase prostate cancer risk.

Prostate cancer and vitamin D: what does the evidence really suggest?

The optimal approach to vitamin D supplementation for the average healthy person is debatable. In patients with cancer, the role of vitamin D supplementation, possibly in treatment, is even less clear. Vitamin D is shown to play a role in prostate cancer biology; however, the clinical data have not consistently demonstrated a link. Additional studies are needed to determine if higher doses of vitamin D supplements could benefit selected populations (ie, the elderly or patients with cancer) even if they may not be beneficial for the general population.

Dairy Products in the Food Chain: Their Impact on Health

Milk is a complex and complete food containing an array of essential nutrients that contribute toward a healthy, balanced diet. Numerous epidemiological studies have revealed that high consumption of milk and dairy products may have protective effects against coronary heart disease (CHD), stroke, diabetes, certain cancers (such as colorectal and bladder cancers), and dementia, although the mechanisms of action are unclear. Despite this epidemiological evidence, milk fatty acid profiles often lead to a negative perception of milk and dairy products. However, altering the fatty acid profile of milk by changing the dairy cow diet is a successful strategy, and intervention studies have shown that this approach may lead to further benefits of milk/dairy consumption. Overall, evidence suggests individuals who consume a greater amount of milk and dairy products have a slightly better health advantage than those who do not consume milk and dairy products.

Associations of circulating and dietary vitamin D with prostate cancer risk: a systematic review and dose-response meta-analysis

OBJECTIVE

We systematically reviewed and meta-analyzed literature examining associations of vitamin D (dietary intake, circulating 25-hydroxy-vitamin-D (25(OH)D), and 1,25-dihydroxy-vitamin-D (1,25(OH)(2)D) concentrations) with prostate cancer.

METHODS

We searched over 24,000 papers from seven electronic databases (to October 2010) for exposures related to vitamin D. We conducted dose-response random-effects meta-analyses pooling the log odds ratio (OR) and 95% confidence intervals (CI) per change in natural units of each exposure. The I(2) statistic quantified between-study variation due to heterogeneity.

RESULTS

Twenty-five papers were included. In prospective studies, the OR per 1,000 IU increase in dietary intake was 1.14 (6 studies; CI: 0.99, 1.31; I (2) = 0%) for total prostate cancer and 0.93 (3 studies; 0.63, 1.39; I (2) = 25%) for aggressive prostate cancer. Five case-control studies examined dietary intake, but there was a high degree of inconsistency between studies (I (2) = 49%). The OR per 10 ng/mL increase in 25(OH)D was 1.04 (14 studies; 0.99, 1.10; I (2) = 0%) for total prostate cancer and 0.98 (6 studies; 0.84, 1.15; I (2) = 32%) for aggressive prostate cancer. The OR per 10 pg/mL increase in 1,25(OH)(2)D was 1.00 (7 studies; 0.87, 1.14; I (2) = 41%) for total prostate cancer and 0.86 (2 studies; 0.72, 1.02; I (2) = 0%) for aggressive prostate cancer.

CONCLUSION

Published literature provides little evidence to support a major role of vitamin D in preventing prostate cancer or its progression.

Nutrients and risk of prostate cancer

This study assesses the association between intake of protein, fats, cholesterol, and carbohydrates and the risk of prostate cancer (PCa). Between 1994 and 1997, in 8 Canadian provinces, mailed questionnaires were completed by 1,797 incident, histologically confirmed cases of PCa and 2,547 population controls. Information was collected on socioeconomic status, lifestyle habits, and diet. A 69-item food frequency questionnaire provided data on eating habits 2 yr before the study. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using unconditional logistic regression, including terms for sociodemographic factors, body mass index, alcohol, and total energy intake. Intake of trans fat was associated with the risk of PCa; the OR for the highest vs. the lowest quartile was 1.45 (95% CI = 1.16-1.81); the association was apparently stronger in subjects aged less than 65, normal weight men, and ever smokers. An increased risk was also observed with increasing intake of sucrose and disaccharides. In contrast, men in the highest quartile of cholesterol intake were at lower risk of PCa. No association was found with intake of total proteins, total fat, monounsaturated fats, polyunsaturated fats, monosaccharides, and total carbohydrates. The findings provide evidence that a diet low in trans fat could reduce PCa risk.

A review and meta-analysis of prospective studies of red and processed meat intake and prostate cancer

Over the past decade, several large epidemiologic investigations of meat intake and prostate cancer have been published. Therefore, a meta-analysis of prospective studies was conducted to estimate potential associations between red or processed meat intake and prostate cancer. Fifteen studies of red meat and 11 studies of processed meat were included in the analyses. High vs. low intake and dose-response analyses were conducted using random effects models to generate summary relative risk estimates (SRRE). No association between high vs. low red meat consumption (SRRE = 1.00, 95% CI: 0.96-1.05) or each 100 g increment of red meat (SRRE = 1.00, 95% CI: 0.95-1.05) and total prostate cancer was observed. Similarly, no association with red meat was observed for advanced prostate cancer (SRRE = 1.01, 95% CI: 0.94-1.09). A weakly elevated summary association between processed meat and total prostate cancer was found (SRRE = 1.05, 95% CI: 0.99-1.12), although heterogeneity was present, the association was attenuated in a sub-group analysis of studies that adjusted for multiple potential confounding factors, and publication bias likely affected the summary effect. In conclusion, the results of this meta-analysis are not supportive of an independent positive association between red or processed meat intake and prostate cancer.

Diet and prostate cancer risk with specific focus on dairy products and dietary calcium: a case-control study

BACKGROUND

Despite the prevalence of prostate cancer worldwide, only a few risk factors have been well-established. The role of diet, especially of dairy products, in the etiology of prostate cancer is still controversial.

METHODS

This study assessed the association of dietary components, particularly dairy products and dietary calcium, on prostate cancer risk in a case-control study of 197 cases and an equal number of individually matched controls recruited in Montreal, Canada. A semi-quantitative food frequency questionnaire was administered in which the usual consumption frequency and amounts consumed of more than 200 food items were recorded.

RESULTS

We found a twofold increased risk of prostate cancer associated with an increased intake of dairy products {Odds Ratio (OR) = 2.19; 95% Confidence Intervals (CI) 1.22-3.94}. A significant trend of decreasing prostate cancer risk with higher intake was found for legumes, nuts, finfish/shellfish and for alpha-tocopherol after adjustment for calcium intake. Milk was the only dairy product significantly associated with prostate cancer risk, with OR = 2.27; 95% CI (1.25-4.09) for the highest versus lowest quartiles of consumption. Calcium, the main micronutrient contained in dairy products, showed only a borderline association with prostate cancer risk (P = 0.09), with slightly higher risk for higher calcium intake. In conclusion, this study supports the hypothesis that dairy products, especially milk, are involved in the etiology of prostate cancer. However, the mechanisms by which the various nutrients in dairy products and total diet may interact to influence this risk remain unknown.

Dietary fat and early-onset prostate cancer risk

The UK incidence of prostate cancer has been increasing in men aged < 60 years. Migrant studies and global and secular variation in incidence suggest that modifiable factors, including a high-fat diet, may contribute to prostate cancer risk. The aim of the present study was to investigate the role of dietary fat intake and its derivatives on early-onset prostate cancer risk. During 1999-2004, a population-based case-control study with 512 cases and 838 controls was conducted. Cases were diagnosed with prostate cancer when < or = 60 years. Controls were sourced from UK GP practice registers. A self-administered FFQ collected data on typical past diet. A nutritional database was used to calculate daily fat intake. A positive, statistically significant risk estimate for the highest v. lowest quintile of intake of total fat, SFA, MUFA and PUFA was observed when adjusted for confounding variables: OR 2.53 (95 % CI 1.72, 3.74), OR 2.49 (95 % CI 1.69, 3.66), OR 2.69 (95 % CI 1.82, 3.96) and OR 2.34 (95 % CI 1.59, 3.46), respectively, with all P for trend < 0.001. In conclusion, there was a positive statistically significant association between prostate cancer risk and energy-adjusted intake of total fat and fat subtypes. These results potentially identify a modifiable risk factor for early-onset prostate cancer.

Vitamin D and prostate cancer risk: a review of the epidemiological literature

Prostate cancer is the most commonly diagnosed cancer in the United States. Prostate cells contain vitamin D receptors as well as enzymes necessary for vitamin D metabolism. Vitamin D metabolites have an antiproliferative and a pro-differentiating effect on prostate cancer cell lines in vitro and in vivo. As a result, there has been an emerging interest in the potential role of vitamin D in the etiology of prostate cancer. This review summarizes all available epidemiological literature on the association between dietary vitamin D, circulating levels of vitamin D and sunlight exposure in relation to prostate cancer risk. To place these studies in context, we also provide some background information on vitamin D, such as its dietary sources, metabolism, optimal levels, hypovitaminosis and relationship with the prostate.

Dairy products, dietary calcium and vitamin D intake as risk factors for prostate cancer: a meta-analysis of 26,769 cases from 45 observational studies

In this study, we examined the available evidence and sources of heterogeneity for studies of dairy products, calcium, and vitamin D intake and the risk of prostate cancer. We pooled data from 45 observational studies using a general variance-based, meta-analytic method employing CIs. Summary relative risks (RRs) were calculated for specific dairy products such as milk and dairy micronutrients. Sensitivity analyses were performed to test the robustness of these summary measures of effect. Cohort studies showed no evidence of an association between dairy [RR = 1.06; 95% confidence interval (CI) = 0.92-1.22] or milk intake (RR = 1.06; 95% CI = 0.91-1.23) and risk of prostate cancer. This was supported by pooled results of case-control analyses (RR = 1.14; 95% CI = 1.00-1.29), although studies using milk as the exposure of interest were heterogeneous and could not be combined. Calcium data from cohort studies were heterogeneous. Case-control analyses using calcium as the exposure of interest demonstrated no association with increased risk of prostate cancer (RR = 1.04; 95% CI = 0.90-1.15). Dietary intake of vitamin D also was not related to prostate cancer risk (RR = 1.16; 95% CI = 0.98-1.38). The data from observational studies do not support an association between dairy product use and an increased risk of prostate cancer.

How much of the data published in observational studies of the association between diet and prostate or bladder cancer is usable for meta-analysis?

Epidemiologic investigations often report dose-response associations, which may be combined in meta-analyses. The authors examined how often the log odds, risk, or hazard ratio per unit increase in exposure, and its standard error, can be estimated from results reported from observational studies of diet and prostate or bladder cancer so that results are usable in meta-analyses estimating dose-response associations. Eight electronic databases were searched for studies reporting on the association of diet, nutrition, or physical activity with these cancers. A total of 767 papers reported 3,284 results; 1,999 (61%) results, reported in 545 (71%) papers, were usable in dose-response meta-analyses. The most important reason that results were not usable was the absence of sufficient information on exposure levels in the different groups. The proportion of results usable in "high-low" meta-analyses (comparisons of extreme categories) was similar (62%). Results that showed evidence of an association were more likely to be usable than results that found no such evidence. Insufficient detail in reporting of results of observational studies can lead to exclusion of these results from meta-analyses and is an important threat to the validity of systematic reviews of such research. Results providing evidence of associations may be overrepresented in meta-analyses of observational studies.

Dietary fat intake and risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Findings from early observational studies have suggested that the intake of dietary fat might be a contributing factor in the etiology of prostate cancer. However, the results from more recent prospective studies do not support this hypothesis, and the possible association between different food sources of fat and prostate cancer risk also remains unclear.

OBJECTIVE

The objectives were to assess whether intakes of dietary fat, subtypes of fat, and fat from animal products were associated with prostate cancer risk.

DESIGN

This was a multicenter prospective study of 142,520 men in the European Prospective Investigation into Cancer and Nutrition (EPIC). Dietary fat intake was estimated with the use of country-specific validated food questionnaires. The association between dietary fat and risk of prostate cancer was assessed by using Cox regression, stratified by recruitment center and adjusted for height, weight, smoking, education, marital status, and energy intake.

RESULTS

After a median follow-up time of 8.7 y, prostate cancer was diagnosed in 2727 men. There was no significant association between dietary fat (total, saturated, monounsaturated, and polyunsaturated fat and the ratio of polyunsaturated to saturated fat) and risk of prostate cancer. The hazard ratio for prostate cancer for the highest versus the lowest quintile of total fat intake was 0.96 (95% CI: 0.84, 1.09; P for trend = 0.155). There were no significant associations between prostate cancer risk and fat from red meat, dairy products, and fish.

CONCLUSION

The results from this large multicenter study suggest that there is no association between dietary fat and prostate cancer risk.

Animal foods, protein, calcium and prostate cancer risk: the European Prospective Investigation into Cancer and Nutrition

We examined consumption of animal foods, protein and calcium in relation to risk of prostate cancer among 142 251 men in the European Prospective Investigation into Cancer and Nutrition. Associations were examined using Cox regression, stratified by recruitment centre and adjusted for height, weight, education, marital status and energy intake. After an average of 8.7 years of follow-up, there were 2727 incident cases of prostate cancer, of which 1131 were known to be localised and 541 advanced-stage disease. A high intake of dairy protein was associated with an increased risk, with a hazard ratio for the top versus the bottom fifth of intake of 1.22 (95% confidence interval (CI): 1.07–1.41, P_trend=0.02). After calibration to allow for measurement error, we estimated that a 35-g day⁻¹ increase in consumption of dairy protein was associated with an increase in the risk of prostate cancer of 32% (95% CI: 1–72%, P_trend=0.04). Calcium from dairy products was also positively associated with risk, but not calcium from other foods. The results support the hypothesis that a high intake of protein or calcium from dairy products may increase the risk for prostate cancer.

Vitamin D and cancer incidence in the Harvard cohorts

Since the hypothesis that vitamin D reduces the risk of some cancers was initiated in 1980, this hypothesis has been studied in the Harvard cohort studies, including the Nurses' Health Study (NHS), the Health Professionals Follow-Up Study (HPFS), and the Physicians' Health Study (PHS). Three approaches have been used, the study of circulating 25(OH)vitamin D (25(OH)D) level, of dietary and supplementary intake, and of predicted 25(OH)D. These cohorts strongly support an inverse association with colorectal cancer, because this association has been viewed in both the NHS and HPFS cohorts, for cancers and adenomas, and for plasma, diet, and predicted 25(OH)D analyses. In the NHS, about a 30% reduction in risk was observed for breast cancer comparing the highest with lowest quintiles of 25(OH)D levels. Vitamin D intake also was associated with a lower risk of pancreatic cancer in both men and women, but studies of plasma or predicted 25(OH)D level or dietary intake have generally not been supportive of a major role of vitamin D status in middle-age or elderly men on prostate cancer risk. Results from the HPFS also suggest that the poor vitamin D status generally in African-Americans contributes to their higher incidence and mortality from various malignancies.