Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer (Sweden)

Correlative Analysis of Vitamin D and Omega-3 Fatty Acid Intake in Men on Active Surveillance for Prostate Cancer

OBJECTIVE

To investigate the influence of targeted serum vitamin-D level and omega-6:3 fatty-acid ratio on prostate-specific antigen (PSA) level in men with prostate cancer managed with active surveillance by providing a nutritional intervention and vitamin supplementation.

METHODS

Sixty-eight patients with biopsy-proven National Comprehensive Cancer Network very-low or low-risk prostate cancer were enrolled in the prostate cancer nutrition and genetics clinic at the Cleveland Clinic from July 2013-December 2019. Patients adhered to a specific dietary regimen devoid of animal-based products and foods containing omega-6 polyunsaturated fatty acids (PUFAs). The supplement regimen consisted of: Omega-3 PUFAs 720mg (3/day); curcumin 2000 mg/day; vitamin D3 dose titrated to achieve serum level of 60 ng/ml; and vitamin B-complex 1000 mg (4 times weekly). Patients underwent periodic monitoring of PSA, serum vitamin D, and PUFA levels and had frequent follow-up with the nutritionist which included a food frequency questionnaire. Interval prostate biopsy was performed as clinically indicated and/or at 9 months.

RESULTS

The mean and 95% confidence interval of PSA slope and Vitamin D serum levels slope were 0.11 (0-0.25) ng/mL/month and 4.65 (3.09-5.98) ng/mL/month, respectively. Patients with higher initial vitamin D levels were twice as likely to have a downward PSA trend (OR = 2.04, 95% confidence interval 1.04-4.01, P = .04). Fifty-five patients underwent follow-up biopsy, all showing no progression of disease. Three patients had loose bowel movements that required omega-3 and or curcumin dose adjustments.

CONCLUSION

Intensive nutritional intervention with Vitamin D and Omega-3 PUFA supplementation may benefit men on active surveillance for prostate cancer and further studies are warranted.

Dietary Carcinogens and DNA Adducts in Prostate Cancer

Prostate cancer (PC) is the most commonly diagnosed non-cutaneous cancer and the second leading cause of cancer-related to death in men. The major risk factors for PC are age, family history, and African American ethnicity. Epidemiological studies have reported large geographical variations in PC incidence and mortality, and thus lifestyle and dietary factors influence PC risk. High fat diet, dairy products, alcohol and red meats, are considered as risk factors for PC. This book chapter provides a comprehensive, literature-based review on dietary factors and their molecular mechanisms of prostate carcinogenesis. A large portion of our knowledge is based on epidemiological studies where dietary factors such as cancer promoting agents, including high-fat, dairy products, alcohol, and cancer-initiating genotoxicants formed in cooked meats have been evaluated for PC risk. However, the precise mechanisms in the etiology of PC development remain uncertain. Additional animal and human cell-based studies are required to further our understandings of risk factors involved in PC etiology. Specific biomarkers of chemical exposures and DNA damage in the prostate can provide evidence of cancer-causing agents in the prostate. Collectively, these studies can improve public health research, nutritional education and chemoprevention strategies.

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.

Mendelian randomization does not support serum calcium in prostate cancer risk

PURPOSE

Observational studies suggest that dietary and serum calcium are risk factors for prostate cancer. However, such studies suffer from residual confounding (due to unmeasured or imprecisely measured confounders), undermining causal inference. Mendelian randomization uses randomly assigned (hence unconfounded and pre-disease onset) germline genetic variation to proxy for phenotypes and strengthen causal inference in observational studies. We tested the hypothesis that serum calcium is associated with an increased risk of overall and advanced prostate cancer.

METHODS

A genetic instrument was constructed using five single-nucleotide polymorphisms robustly associated with serum calcium in a genome-wide association study (n ≤ 61,079). This instrument was then used to test the effect of a 0.5 mg/dL increase (1 standard deviation, SD) in serum calcium on risk of prostate cancer in 72,729 men in the PRACTICAL (Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome) Consortium (44,825 cases, 27,904 controls) and risk of advanced prostate cancer in 33,498 men (6,263 cases, 27,235 controls).

RESULTS

We found weak evidence for a protective effect of serum calcium on prostate cancer risk (odds ratio [OR] per 0.5 mg/dL increase in calcium: 0.83, 95% CI 0.63-1.08; p = 0.12). We did not find strong evidence for an effect of serum calcium on advanced prostate cancer (OR per 0.5 mg/dL increase in calcium: 0.98, 95% CI 0.57-1.70; p = 0.93).

CONCLUSIONS

Our Mendelian randomization analysis does not support the hypothesis that serum calcium increases risk of overall or advanced prostate cancer.

Treatment Options in Hormone-refractory Metastatic Prostate Carcinoma

Prostate cancer represents one of the most important health problems in industrialized countries. It is the second leading cause of cancer-related death in the United States. Therapeutic options are different according to the stage of the disease at the diagnosis. Patients with localized disease may be treated with surgery or radiation, whereas the treatment for patients with a metastatic disease is purely palliative. Hormonal treatment represents the standard therapy for stage IV prostate cancer, but patients ultimately become unresponsive to androgen ablation and are classified as hormone-refractory prostate cancer patients. The molecular mechanisms involved in progression in hormone resistance are characterized by mutations, down and up-regulation in the androgen receptor gene, mutations in p53 and over-expression of Bcl2 and other alterations in genes and in gene expression. The important thing is that we understand these mechanisms to define potential therapeutic agents for the treatment of hormone-refractory prostate cancer patients. Conventional options for patients with hormone-refractory prostate cancer include secondary hormone therapy, radiotherapy and cytotoxic chemotherapy. The commonest antineoplastic agents are mitoxantrone, estramustine and taxanes. Despite an improvement In the palliative benefit, none of these agents has demonstrated a beneficial impact on the overall survival of patients. Therefore, there is no standard therapy for these patients, thus we need new approaches which should be studied in clinical trials. The evaluation and incorporation of new agents into current treatment regimens could have a role in the treatment of hormone-refractory prostate cancer, but their efficacy has not yet been demonstrated.

Milk and other dairy foods in relation to prostate cancer recurrence: Data from the cancer of the prostate strategic urologic research endeavor (CaPSURE™)

BACKGROUND

High-fat dairy, particularly whole milk, in healthy men may increase risk of aggressive prostate cancer. However, data are limited regarding dairy after prostate cancer diagnosis.

METHOD

We conducted a prospective study among 1334 men with non-metastatic prostate cancer in the Cancer of the Prostate Strategic Urologic Research Endeavor. Men answered a food frequency questionnaire in 2004-2005 (median 2 years after diagnosis) and were followed until 2016 for recurrence, defined as: prostate cancer death, bone metastases, biochemical recurrence, or secondary treatment. Multivariate Cox proportional hazards regression was used to calculate hazards ratios (HR) and 95% confidence intervals (CI) for associations between whole and low-fat milk; total, high-fat, and low-fat dairy; and other dairy items and risk of recurrence.

RESULTS

During a median follow-up of 8 years, we observed 137 events. Men who consumed >4 servings/week versus 0-3 servings/month of whole milk had an 73% increased risk of recurrence (HR: 1.73; 95%CI: 1.00, 2.98; P-value = 0.04). Body mass index (BMI) modified the association (P-interaction = 0.01). Among men with a BMI ≥27 kg/m² , >4 servings/week versus 0-3 servings/month of whole milk was associated with a 3-fold higher risk of recurrence (HR: 2.96; 95%CI: 1.58, 5.54; P-value < 0.001). No association was seen in men with BMI <27 kg/m² . Low-fat milk and other dairy foods were not associated with recurrence.

CONCLUSION

In conclusion, whole milk consumption after prostate cancer diagnosis was associated with increased risk of recurrence, particularly among very overweight or obese men. Men with prostate cancer who choose to drink milk should select non-fat or low-fat options.

Risk Model for Prostate Cancer Using Environmental and Genetic Factors in the Spanish Multi-Case-Control (MCC) Study

Prostate cancer (PCa) is the second most common cancer among men worldwide. Its etiology remains largely unknown compared to other common cancers. We have developed a risk stratification model combining environmental factors with family history and genetic susceptibility. 818 PCa cases and 1,006 healthy controls were compared. Subjects were interviewed on major lifestyle factors and family history. Fifty-six PCa susceptibility SNPs were genotyped. Risk models based on logistic regression were developed to combine environmental factors, family history and a genetic risk score. In the whole model, compared with subjects with low risk (reference category, decile 1), those carrying an intermediate risk (decile 5) had a 265% increase in PCa risk (OR = 3.65, 95% CI 2.26 to 5.91). The genetic risk score had an area under the ROC curve (AUROC) of 0.66 (95% CI 0.63 to 0.68). When adding the environmental score and family history to the genetic risk score, the AUROC increased by 0.05, reaching 0.71 (95% CI 0.69 to 0.74). Genetic susceptibility has a stronger risk value of the prediction that modifiable risk factors. While the added value of each SNP is small, the combination of 56 SNPs adds to the predictive ability of the risk model.

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.

Are strict vegetarians protected against prostate cancer?

BACKGROUND

According to the American Cancer Society, prostate cancer accounts for ∼27% of all incident cancer cases among men and is the second most common (noncutaneous) cancer among men. The relation between diet and prostate cancer is still unclear. Because people do not consume individual foods but rather foods in combination, the assessment of dietary patterns may offer valuable information when determining associations between diet and prostate cancer risk.

OBJECTIVE

This study aimed to examine the association between dietary patterns (nonvegetarian, lacto-ovo-vegetarian, pesco-vegetarian, vegan, and semi-vegetarian) and prostate cancer incidence among 26,346 male participants of the Adventist Health Study-2.

DESIGN

In this prospective cohort study, cancer cases were identified by matching to cancer registries. Cox proportional hazards regression analysis was performed to estimate HRs by using age as the time variable.

RESULTS

In total, 1079 incident prostate cancer cases were identified. Around 8% of the study population reported adherence to the vegan diet. Vegan diets showed a statistically significant protective association with prostate cancer risk (HR: 0.65; 95% CI: 0.49, 0.85). After stratifying by race, the statistically significant association with a vegan diet remained only for the whites (HR: 0.63; 95% CI: 0.46, 0.86), but the multivariate HR for black vegans showed a similar but nonsignificant point estimate (HR: 0.69; 95% CI: 0.41, 1.18).

CONCLUSION

Vegan diets may confer a lower risk of prostate cancer. This lower estimated risk is seen in both white and black vegan subjects, although in the latter, the CI is wider and includes the null.

Incidence of prostate and urological cancers in England by ethnic group, 2001-2007: a descriptive study

Background

The aetiology of urological cancers is poorly understood and variations in incidence by ethnic group may provide insights into the relative importance of genetic and environmental risk factors. Our objective was to compare the incidence of four urological cancers (kidney, bladder, prostate and testicular) among six ‘non-White’ ethnic groups in England (Indian, Pakistani, Bangladeshi, Black African, Black Caribbean and Chinese) to each other and to Whites.

Methods

We obtained Information on ethnicity for all urological cancer registrations from 2001 to 2007 (n = 329,524) by linkage to the Hospital Episodes Statistics database. We calculated incidence rate ratios adjusted for age, sex and income, comparing the six ethnic groups (and combined ‘South Asian’ and ‘Black’ groups) to Whites and to each other.

Results

There were significant differences in the incidence of all four cancers between the ethnic groups (all p < 0.001). In general, ‘non-White’ groups had a lower incidence of urological cancers compared to Whites, except prostate cancer, which displayed a higher incidence in Blacks. (IRR 2.55) There was strong evidence of differences in risk between Indians, Pakistanis and Bangladeshis for kidney, bladder and prostate cancer (p < 0.001), and between Black Africans and Black Caribbeans for all four cancers (p < 0.001).

Conclusions

The risk of urological cancers in England varies greatly by ethnicity, including within groups that have traditionally been analysed together (South Asians and Blacks). In general, these differences are not readily explained by known risk factors, although the very high incidence of prostate cancer in both black Africans and Caribbeans suggests increased genetic susceptibility. g.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1771-2) contains supplementary material, which is available to authorized users.

Dairy intake after prostate cancer diagnosis in relation to disease-specific and total mortality

Information regarding postdiagnostic dairy intake and prostate cancer survival is limited. We evaluated intake of total, high-fat and low-fat dairy after prostate cancer diagnosis in relation to disease-specific and total mortality. We included 926 men from the Physicians' Health Study diagnosed with non-metastatic prostate cancer between 1982 and 2000 who completed a diet questionnaire a median of 5 years after diagnosis and were followed thereafter for a median of 10 years to assess mortality. Cox proportional hazards regression was used to estimate associations between dairy intake and prostate cancer specific and all-cause mortality. During 8,903 person-years of follow-up, 333 men died, 56 due to prostate cancer. Men consuming ≥3 servings/day of total dairy products had a 76% higher risk of total mortality and a 141% higher risk of prostate cancer-specific mortality compared to men who consumed less than 1 dairy product/day (hazard ratio (HR) = 1.76, 95% confidence interval (CI): 1.21, 2.55, ptrend  < 0.001 for total mortality; HR = 2.41, 95% CI: 0.96, 6.02, ptrend  = 0.04 for prostate cancer-specific mortality). The association between high-fat dairy and mortality risk appeared to be stronger than that of low-fat dairy, but the difference between them was not statistically significant (p for difference = 0.57 for prostate cancer-specific mortality and 0.56 for total mortality). Among men without metastases when diagnosed, higher intake of dairy foods after prostate cancer diagnosis may be associated with increased prostate cancer-specific and all-cause mortality.

Association between dietary inflammatory index and prostate cancer among Italian men

Previous studies have shown that various dietary components may be implicated in the aetiology of prostate cancer, although the results remain equivocal. The possible relationship of inflammation derived from dietary exposures with prostate cancer risk has not been investigated. We examined the ability of a newly developed dietary inflammatory index (DII) to predict prostate cancer risk in a case-control study conducted in Italy between 1991 and 2002. A total of 1294 patients aged < 75 years with incident, histologically confirmed carcinoma of the prostate served as cases. A total of 1451 subjects aged < 75 years who were admitted to the same hospitals as cases for a wide spectrum of acute, non-neoplastic conditions served as controls. The DII was computed based on dietary intake assessed using a previously validated seventy-eight-item FFQ. Logistic regression models were used to estimate multivariable OR adjusted for age, study centre, years of education, social class, BMI, smoking status, family history of prostate cancer and total energy intake. Men with higher DII scores had a higher risk of prostate cancer when analysed using the DII as both continuous (OR 1.06, 95% CI 1.00, 1.13) and categorical, i.e., compared with men in the lowest quartile of the DII, men in the third and fourth quartiles were at elevated risk (OR(Quartile 3 v. 1) 1.32, 95% CI 1.03, 1.69 and OR(Quartile 4 v. 1) 1.33, 95% CI 1.01, 1.76; P trend= 0.04). These data suggest that a pro-inflammatory diet, as indicated by the increasing DII score, is a risk factor of prostate cancer in Italian men.

Association between dietary folate intake and serum insulin-like growth factor-1 levels in healthy old women

OBJECTIVE

High serum levels of insulin-like growth factor-1 (IGF-1) seem to coincide with higher rates of some types of cancer and the risk of all-cause mortality in old people. Eating vegetables seems to reduce IGF-1 levels because they are rich in micronutrients such as vitamins. This study investigates the possible association between vitamin intake and IGF-1 levels in a representative group of healthy elderly women with Mediterranean dietary habits.

DESIGN

This cross-sectional study included 124 healthy women with a mean age of 71.3 ± 4.2 years and a mean body mass index (BMI) of 27.37 ± 3.48 kg/m(2) attending a mild fitness program twice a week at public gyms in Padova. The main parameters considered were IGF-1 (measured by chemiluminescence) and diet, assessed on the basis of a 3-day record and a questionnaire on the frequency with which they usually ate certain foods.

RESULTS

The mean IGF-1 level for the sample as a whole was 136.2 ± 38.9 μg/l, and was significantly lower in women with a higher folate intake (p = 0.04). On simple linear analysis, the vitamins found associated with serum IGF-1 levels were: folates (r: -0.25; p = 0.003); vitamin E (r: -0.21; p = 0.01); vitamin D (r: -0.17; p = 0.03); and riboflavin (r: -0.16; p=0.03). After removing the effect of calorie, protein, carbohydrate and fat intake, and other known potential confounders (age, BMI, alcohol intake), only folate intake correlated with IGF-1 levels (r = -0.17; p = 0.04).

CONCLUSION

A folate-rich diet could have the effect of lowering circulating IGF-1 levels in elderly women.

Calcium supplements and cancer risk: a meta-analysis of randomised controlled trials

Some evidence suggests that Ca and vitamin D supplements affect cancer risk; however, it is uncertain whether the effects are due to Ca, vitamin D or the combination. We investigated the effect of Ca supplements without co-administered vitamin D on cancer risk. Medline, Embase and the Cochrane Central Register of Controlled Trials, reference lists of meta-analyses and two clinical trial registries were searched for randomised, placebo-controlled trials of Ca supplements ( ≥ 500 mg/d), with ≥ 100 participants and duration >1 year. The lead authors of eligible trials supplied data on cancer outcomes. Trial-level data were analysed using random-effects meta-analyses and patient-level data using Cox proportional hazards models. A total of sixteen trials were eligible, six had no data available, ten provided trial-level data (n 10 496, mean duration 3·9 years), and of these, four provided patient-level data (n 7221, median duration 3·5 years). In the meta-analysis of trial-level data, allocation to Ca did not alter the risk of total cancer (relative risk 0·95, 95 % CI 0·76, 1·18, P= 0·63), colorectal cancer (relative risk 1·38, 95 % CI 0·89, 2·15, P= 0·15), breast cancer (relative risk 1·01, 95 % CI 0·64, 1·59, P= 0·97) or cancer-related mortality (relative risk 0·96, 95 % CI 0·74, 1·24, P= 0·75), but reduced the risk of prostate cancer (relative risk 0·54, 95 % CI 0·30, 0·96, P= 0·03), although there were few events. The meta-analysis of patient-level data showed similar results, with no effect of Ca on the risk of total cancer (hazard ratio 1·07, 95 % CI 0·89, 1·28, P= 0·50). Ca supplements without co-administered vitamin D did not alter total cancer risk over 4 years, although the meta-analysis lacked power to detect very small effects, or those with a longer latency.

Whole milk intake is associated with prostate cancer-specific mortality among U.S. male physicians

Previous studies have associated higher milk intake with greater prostate cancer (PCa) incidence, but little data are available concerning milk types and the relation between milk intake and risk of fatal PCa. We investigated the association between intake of dairy products and the incidence and survival of PCa during a 28-y follow-up. We conducted a cohort study in the Physicians' Health Study (n = 21,660) and a survival analysis among the incident PCa cases (n = 2806). Information on dairy product consumption was collected at baseline. PCa cases and deaths (n = 305) were confirmed during follow-up. The intake of total dairy products was associated with increased PCa incidence [HR = 1.12 (95% CI: 0.93, 1.35); >2.5 servings/d vs. ≤0.5 servings/d]. Skim/low-fat milk intake was positively associated with risk of low-grade, early stage, and screen-detected cancers, whereas whole milk intake was associated only with fatal PCa [HR = 1.49 (95% CI: 0.97, 2.28); ≥237 mL/d (1 serving/d) vs. rarely consumed]. In the survival analysis, whole milk intake remained associated with risk of progression to fatal disease after diagnosis [HR = 2.17 (95% CI: 1.34, 3.51)]. In this prospective cohort, higher intake of skim/low-fat milk was associated with a greater risk of nonaggressive PCa. Most importantly, only whole milk was consistently associated with higher incidence of fatal PCa in the entire cohort and higher PCa-specific mortality among cases. These findings add further evidence to suggest the potential role of dairy products in the development and prognosis of PCa.

Sunlight, vitamin D and the prevention of cancer: a systematic review of epidemiological studies

The number of studies reporting beneficial effects of sunlight and vitamin D on several types of cancer with a high mortality rate is growing rapidly. Present health recommendations on sun exposure are mainly based on the increased risks for skin cancer. We reviewed all published studies concerning cancer and sun exposure and vitamin D, respectively, excluding those about skin cancer. Most identified ecological, case-control and prospective studies on the incidence and mortality of colorectal, prostate, breast carcinoma and non-Hodgkin lymphoma reported a significantly inverse association with sun exposure. The results of the included studies on the association between cancer risk and vitamin D were much less consistent. Only those studies that prospectively examined the 25-hydroxyvitamin D serum levels in relation to risk of colorectal cancer are homogeneous: they all reported inverse associations, although not all reaching statistical significance. The results of the intervention studies are suggestive of a protective role of high doses of vitamin D in cancer, but they have been criticized in the literature. We, therefore, conclude that there is accumulating evidence for sunlight as a protective factor for several types of cancer. The same conclusion can be made concerning high vitamin D levels and the risk of colorectal cancer. This evidence, however, is not conclusive, because the number of (good quality) studies is still limited and publication biases cannot be excluded. The discrepancies between the epidemiological evidence for a possible preventive effect of sunlight and vitamin D and the question of how to apply the findings on the beneficial effects of sunlight to (public) health recommendations are discussed.

The impact of cow's milk-mediated mTORC1-signaling in the initiation and progression of prostate cancer

Prostate cancer (PCa) is dependent on androgen receptor signaling and aberrations of the PI3K-Akt-mTORC1 pathway mediating excessive and sustained growth signaling. The nutrient-sensitive kinase mTORC1 is upregulated in nearly 100% of advanced human PCas. Oncogenic mTORC1 signaling activates key subsets of mRNAs that cooperate in distinct steps of PCa initiation and progression. Epidemiological evidence points to increased dairy protein consumption as a major dietary risk factor for the development of PCa. mTORC1 is a master regulator of protein synthesis, lipid synthesis and autophagy pathways that couple nutrient sensing to cell growth and cancer. This review provides evidence that PCa initiation and progression are promoted by cow´s milk, but not human milk, stimulation of mTORC1 signaling. Mammalian milk is presented as an endocrine signaling system, which activates mTORC1, promotes cell growth and proliferation and suppresses autophagy. Naturally, milk-mediated mTORC1 signaling is restricted only to the postnatal growth phase of mammals. However, persistent consumption of cow´s milk proteins in humans provide highly insulinotropic branched-chain amino acids (BCAAs) provided by milk´s fast hydrolysable whey proteins, which elevate postprandial plasma insulin levels, and increase hepatic IGF-1 plasma concentrations by casein-derived amino acids. BCAAs, insulin and IGF-1 are pivotal activating signals of mTORC1. Increased cow´s milk protein-mediated mTORC1 signaling along with constant exposure to commercial cow´s milk estrogens derived from pregnant cows may explain the observed association between high dairy consumption and increased risk of PCa in Westernized societies. As well-balanced mTORC1-signaling plays an important role in appropriate prostate morphogenesis and differentiation, exaggerated mTORC1-signaling by high cow´s milk consumption predominantly during critical growth phases of prostate development and differentiation may exert long-term adverse effects on prostate health. Attenuation of mTORC1 signaling by contemporary Paleolithic diets and restriction of dairy protein intake, especially during mTORC1-dependent phases of prostate development and differentiation, may offer protection from the most common dairy-promoted cancer in men of Western societies.

Dietary fatty acid intake and prostate cancer survival in Örebro County, Sweden

Although dietary fat has been associated with prostate cancer risk, the association between specific fatty acids and prostate cancer survival remains unclear. Dietary intake of 14 fatty acids was analyzed in a population-based cohort of 525 Swedish men with prostate cancer in Örebro County (1989-1994). Multivariable hazard ratios and 95% confidence intervals for time to prostate cancer death by quartile and per standard deviation increase in intake were estimated by Cox proportional hazards regression. Additional models examined the association by stage at diagnosis (localized: T0-T2/M0; advanced: T0-T4/M1, T3-T4/M0). Among all men, those with the highest omega-3 docosahexaenoic acid and total marine fatty acid intakes were 40% less likely to die from prostate cancer (P(trend) = 0.05 and 0.04, respectively). Among men with localized prostate cancer, hazard ratios of 2.07 (95% confidence interval: 0.93, 4.59; P(trend) = 0.03) for elevated total fat, 2.39 (95% confidence interval: 1.06, 5.38) for saturated myristic acid, and 2.88 (95% confidence interval: 1.24, 6.67) for shorter chain (C4-C10) fatty acid intakes demonstrated increased risk for disease-specific mortality for the highest quartile compared with the lowest quartile. This study suggests that high intake of total fat and certain saturated fatty acids may worsen prostate cancer survival, particularly among men with localized disease. In contrast, high marine omega-3 fatty acid intake may improve disease-specific survival for all men.

Food groups and risk of prostate cancer: a case-control study in Uruguay

OBJECTIVE

The role of foods and beverages has been studied in detail in order to establish probable risk factors for prostate cancer.

METHODS

Data were derived from 326 cases with incident and microscopically confirmed adenocarcinomas of the prostate and 652 controls. Odds ratios and 95 % confidence intervals of prostate cancer were estimated by unconditional multiple logistic regression.

RESULTS

We identified the following food items as risk factors: lamb meat, salted meat, whole milk, total eggs, and maté consumption. The highest OR was associated with total eggs (OR, 2.43; 95 % CI, 1.70-3.48), followed by salted meat (OR, 2.65; 95 % CI, 1.36-3.76), maté consumption (OR, 1.96; 95 % CI, 1.17-3.31), and whole milk (OR, 2.01; 95 % CI, 1.26-2.51).

CONCLUSIONS

The final model, fitted by stepwise forward method, included total eggs, salted meat, whole milk, and maté consumption, whereas fruits were protective.

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.

Milk and dairy consumption among men with prostate cancer and risk of metastases and prostate cancer death

BACKGROUND

Whether milk and dairy intake after a prostate cancer diagnosis is associated with a poorer prognosis is unknown. We investigated postdiagnostic milk and dairy intake in relation to risk of lethal prostate cancer (metastases and prostate cancer death) among participants in the Health Professionals Follow-Up Study.

METHODS

The cohort consisted of 3,918 men diagnosed with apparently localized prostate cancer between 1986 and 2006, and followed to 2008. Data on milk and dairy intake were available from repeated questionnaires. We used Cox proportional hazards models to calculate HRs and 95% CIs of the association between postdiagnostic milk and dairy intake and prostate cancer outcomes.

RESULTS

We ascertained 229 prostate cancer deaths and an additional 69 metastases during follow-up. In multivariate analysis, total milk and dairy intakes after diagnosis were not associated with a greater risk of lethal prostate cancer. Men with the highest versus lowest intake of whole milk were at an increased risk of progression (HR = 2.15, 95% CI: 1.28-3.60; P(trend) < 0.01). Men in the highest versus lowest quintile of low-fat dairy intake were at a decreased risk of progression (HR = 0.62; 95% CI: 0.40-0.95; P(trend) = 0.07).

CONCLUSIONS

With the exception of whole milk, our results suggest that milk and dairy intake after a prostate cancer diagnosis is not associated with an increased risk of lethal prostate cancer.

IMPACT

This is the first larger prospective study investigating the relation between postdiagnostic milk and dairy intake and risk of lethal prostate cancer.

Calcium and vitamin D and risk of colorectal cancer: results from a large population-based case-control study in Newfoundland and Labrador and Ontario

BACKGROUND

Previous epidemiological studies have been suggestive but inconclusive in demonstrating inverse associations of calcium, vitamin D, dairy product intakes with risk of colorectal cancer (CRC). We conducted a large population-based comparison of such associations in Newfoundland and Labrador (NL) and Ontario (ON).

METHODS

A case control study design was used. Colorectal cancer cases were new CRC patients aged 20-74 years. Controls were a sex and age-group matched random sample of the population in each province. 1760 cases and 2481 controls from NL and ON were analyzed. Information on dietary intake and lifestyle was collected using self-administered food frequency and personal history questionnaires.

RESULTS

Controls reported higher mean daily intakes of total calcium and total vitamin D than cases in both provinces. In ON, significant reduced CRC risk was associated with intakes of total calcium (OR of highest vs. lowest quintiles was 0.57, 95% CI 0.42-0.77, p(trend) = 0.03), total vitamin D (OR = 0.73, 95% CI 0.54-1.00), dietary calcium (OR = 0.76, 95% CI 0.60-0.97), dietary vitamin D (OR = 0.77, 95% CI 0.61-0.99), total dairy products and milk (OR = 0.78, 95% CI 0.60-1.00), calcium-containing supplements use (OR = 0.76). In NL, the inverse associations of calcium, vitamin D with CRC risk were most pronounced among calcium- or vitamin D-containing supplement users (OR = 0.67, 0.68, respectively).

CONCLUSIONS

Results of this study add to the evidence that total calcium, dietary calcium, total vitamin D, dietary vitamin D, calcium- or vitamin D-containing supplement use may reduce the risk of CRC. The inverse associations of CRC risk with intakes of total dairy products and milk may be largely due to calcium and vitamin D.

Calcium, vitamin D and colorectal cancer chemoprevention

Identifying modifiable risk factors, particularly dietary factors, which have been hypothesized to play an important role in colorectal carcinogenesis, remains crucial in developing primary prevention strategies. Calcium and vitamin D have been shown consistently in experimental studies to have anti-cancerous properties including but not limited to stimulating differentiation, reducing proliferation, and inducing apoptosis. The majority of epidemiologic studies consistently support an approximately 20-30% reduction in risk of colorectal cancer and adenomas comparing high to low intake categories of both calcium and vitamin D, although independent effects may not be adequately separated. Less consistency exists on the dose-response relation for both nutrients. Intake of calcium of not more than 1000 mg/d and intake of vitamin D of 1000-2000 IU/d, achieving a level of at least 30 ng/mL, appear important for colorectal cancer prevention. More study is warranted to determine the optimal intake levels and duration to reduce the colorectal cancer risk.

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.

Dietary zinc and prostate cancer survival in a Swedish cohort

BACKGROUND

Zinc is involved in many essential cellular functions, including DNA repair and immune system maintenance. Although experimental evidence supports a role for zinc in prostate carcinogenesis, epidemiologic data are inconsistent; no data on cancer-specific survival have been reported.

OBJECTIVE

Our objective was to determine whether dietary zinc assessed near the time of prostate cancer diagnosis is associated with improved disease-specific survival.

DESIGN

This population-based cohort consists of 525 men aged <80 y from Örebro County, Sweden, with a diagnosis of prostate cancer made between 1989 and 1994. Study participants completed self-administered food-frequency questionnaires, and zinc intake was derived from nutrient databases. Cox proportional hazards regression was used to estimate multivariate hazard ratios (HRs) and 95% CIs for time to death from prostate cancer as well as death from all causes through February 2009 by quartile (Q) of dietary zinc intake. Models were also stratified by disease stage at diagnosis (localized or advanced).

RESULTS

With a median follow-up of 6.4 y, 218 (42%) men died of prostate cancer and 257 (49%) died of other causes. High dietary zinc intake was associated with a reduced risk of prostate cancer-specific mortality (HR(Q4 vs Q1): 0.64; 95% CI: 0.44, 0.94; P for trend = 0.05) in the study population. The association was stronger in men with localized tumors (HR: 0.24; 95% CI: 0.09, 0.66; P for trend = 0.005). Zinc intake was not associated with mortality from other causes.

CONCLUSION

These results suggest that high dietary intake of zinc is associated with lower prostate cancer-specific mortality after diagnosis, particularly in men with localized disease.

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.

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.

Dairy products and prostate cancer risk

Increased calcium intake from dairy products has been suggested as a risk factor for prostate cancer. We propose that the high dietary phosphate of dairy products may more readily explain this risk rather than the increased calcium. Several epidemiologic correlations have indicated an increased risk of prostate cancer with long-term, high intake of dairy products in male U.S. physicians and males in Sweden. This relation has been mechanistically associated with the higher dietary intake of calcium in dairy products. We propose, however, that the high dietary phosphate of dairy products affects much larger fluctuation in serum phosphate and may be a more likely source of prostate cancer risk from high dietary intake of dairy products.

Epidemiology of vitamin D in health and disease

Results from ecological, case-control and cohort studies have shown that vitamin D reduces the risk of bone fracture, falls, autoimmune diseases, type 2 diabetes, CVD and cancer. However, there is still epidemic vitamin D insufficiency especially among individuals living at high latitudes or with dark skin. Serum levels of 25-hydroxyvitamin D (25(OH)D) are considered the best biomarker of vitamin D nutritional status. Appropriate sunshine exposure or oral supplementation is necessary to maintain sufficient vitamin D status, which is generally accepted as serum 25(OH)D>75 nmol/l. Immunoassays, especially RIA, have been primarily used to measure serum 25(OH)D while liquid chromatography-MS (LC-MS) is considered the 'gold standard'. There is significant disparity among the immunoassays, and all immunoassays have considerable bias compared with LC-MS methods. Because of the variations among the results from these different assays, it is necessary that assay-specific reference ranges be established or standardisation of the assays take place. The present review focuses on ecological, case-control, and cohort studies that investigated the role of vitamin D in health and disease. In addition, analytical techniques used in laboratory evaluation of vitamin D nutritional status are also critically reviewed. The majority of the literature included in the present review is selected from that searchable in PubMed up to the end of September 2008.

Dietary patterns and risk of advanced prostate cancer: a principal component analysis in Uruguay

OBJECTIVE

In order to explore the role of broader eating patterns in the etiology of prostate cancer, we conducted a principal components analysis among Uruguayan men.

METHODS

The study included 345 newly diagnosed cases of advanced prostate cancer and 690 hospitalized controls. The factor analysis was performed using the control population.

RESULTS

Factor analysis allowed the extraction of five patterns, labeled as prudent, traditional, substituter, drinker, and Western. Whereas the traditional and Western patterns were directly associated with risk of prostate cancer (OR for high quartile versus the low quartile of the Western diet was 2.35, 95% CI 1.44-3.85, p-value for trend < 0.0001), the prudent, drinker, and substituter patterns were not associated with risk of the disease. After adjustment of each pattern for the foods with high loadings, these three patterns did not modify substantially their original ORs.

CONCLUSION

The Western and traditional patterns could partially explain the high incidence of advanced prostate cancer in Uruguay, a main producer of beef in the World.

Breast, colorectal, and prostate cancer risk in the European Prospective Investigation into Cancer and Nutrition-Norfolk in relation to phytoestrogen intake derived from an improved database

BACKGROUND

The characterization of phytoestrogen intake and cancer risk has been hindered by the absence of accurate dietary phytoestrogen values.

OBJECTIVE

We examined the risk of breast, colorectal, and prostate cancers relative to phytoestrogen intake on the basis of a comprehensive database.

DESIGN

Demographic and anthropometric characteristics, a medical history, and 7-d records of diet were collected prospectively from participants (aged 40-79 y) in the European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk). Five hundred nine food items were analyzed by liquid chromatography-mass spectrometry/mass spectrometry, and (13)C(3)-labeled internal standards were analyzed for isoflavones (genistein, daidzein, glycitein, biochanin A, and formononetin), lignans (secoisolariciresinol and matairesinol), and enterolignans from gut microbial metabolism in animal food sources (equol and enterolactone). From the direct analysis, values for 10,708 foods were calculated. Odds ratios (ORs) for breast (244 cases, 941 controls), colorectal (221 cases, 886 controls), and prostate (204 cases, 812 controls) cancers were calculated relative to phytoestrogen intake.

RESULTS

Phytoestrogen intake was not associated with breast cancer among women or colorectal cancer among men. Among women, colorectal cancer risk was inversely associated with enterolactone (OR: 0.33; 95% CI: 0.14, 0.74) and total enterolignans (OR: 0.32; 95% CI: 0.13, 0.79), with a positive trend detected for secoisolariciresinol (OR: 1.60; 95% CI: 0.96, 2.69). A positive trend between enterolignan intake and prostate cancer risk (OR: 1.27; 95% CI: 0.97, 1.66) was attenuated after adjustment for dairy intake (OR: 1.19; 95% CI: 0.77, 1.82).

CONCLUSION

Dietary phytoestrogens may contribute to the risk of colorectal cancer among women and prostate cancer among men.

Meta-analysis of longitudinal studies: Serum vitamin D and prostate cancer risk

AIM

To review and summarize evidence from longitudinal studies on the association between serum 25-hydroxyvitamin D (25(OH)D) and the risk of prostate cancer (PC).

METHODS

Relevant prospective cohort studies and nested case-control studies published until July 2009 were identified by systematically searching Ovid Medline, EMBASE, and ISI Web of Knowledge databases and by cross-referencing. The following data were extracted in a standardized manner from eligible studies: first author, publication year, country, study design, characteristics of the study population, duration of follow-up, PC incidence/PC mortality according to serum vitamin D status and the respective risk ratios, and covariates adjusted for in the analysis. Due to the heterogeneity of studies in categorizing serum vitamin D levels, all results were recalculated for an increase in serum 25(OH)D by 10ng/ml. Summary odds ratios (ORs) were calculated using meta-analysis methods.

RESULTS

Overall, eleven original articles were included, ten of which reported on the association between serum vitamin D levels and PC incidence and one article reported on the association with PC mortality. Meta-analysis of studies on PC incidence resulted in a summary OR (95% confidence interval, CI) of 1.03 (0.96-1.11) associated with an increase of 25(OH)D by 10ng/ml (P=0.362). No indication for heterogeneity and publication bias was found.

CONCLUSIONS

According to available evidence from longitudinal studies, serum 25(OH)D is not associated with PC incidence.

One-carbon metabolism-related nutrients and prostate cancer survival

BACKGROUND

Folate and other one-carbon metabolism nutrients may influence prostate cancer pathogenesis. Prior studies of these nutrients in relation to prostate cancer incidence have been inconclusive, and none have explored prostate cancer survival.

OBJECTIVE

The objective was to assess whether dietary intakes of folate, riboflavin, vitamin B-6, vitamin B-12, and methionine measured around the time of prostate cancer diagnosis are associated with prostate cancer survival.

DESIGN

This population-based prospective study comprised 525 men from Orebro, Sweden, who received a diagnosis of incident prostate cancer between 1989 and 1994 and completed a self-administered food-frequency questionnaire. Record linkages to the Swedish Death Registry enabled all cases to be followed for up to 20 y after diagnosis, and the cause of death was assigned via medical record review. Cox proportional hazards regression was used to calculate multivariable hazard ratios (HRs) and 95% CIs. During a median of 6.4 y of follow-up, 218 men (42%) died of prostate cancer and 257 (49%) of other causes.

RESULTS

A comparison of the highest with the lowest quartile showed that vitamin B-6 intake was inversely associated with prostate cancer-specific death (HR: 0.71; 95% CI: 0.46, 1.10; P for trend = 0.08), especially in men with a diagnosis of localized-stage disease (HR; 0.05; 95% CI: 0.01, 0.26; P for trend = 0.0003). However, vitamin B-6 intake was not associated with improved prostate cancer survival among advanced-stage cases (HR: 1.04; 95% CI: 0.64, 1.72; P for trend = 0.87). Folate, riboflavin, vitamin B-12, and methionine intakes were not associated with prostate cancer survival.

CONCLUSION

A high vitamin B-6 intake may improve prostate cancer survival among men with a diagnosis of localized-stage disease.

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.

Intake of dairy products and risk of colorectal neoplasia

Prospective cohort studies suggest that higher intakes of dairy products, in particular milk, are associated with a decreased risk of colorectal cancer (CRC). In Western populations, dairy products are major contributors to dietary Ca, which may have chemopreventive effects in the colon. The pooling of data from prospective studies suggests a significant protective effect of Ca on CRC risk. Randomised controlled trials with Ca supplements have been conducted with both colorectal adenoma and CRC as endpoints. Results suggest that Ca supplementation at a level of 1000-2000 mg/d reduces adenoma recurrence in individuals with a previous adenoma but has no effect on CRC incidence. There is evidence that the risk reduction from dairy foods may not be solely due to their high Ca content. Dairy products contain other potential chemopreventive components such as vitamin D, butyric acid, conjugated linoleic acid, sphingolipids, and probiotic bacteria in fermented products such as yoghurt. The present review will focus on the epidemiological evidence (and in particular prospective cohort studies) investigating the relationship between dairy product consumption and risk of CRC. An outline of the proposed mechanisms responsible for the protective effect of both Ca and other potential chemopreventive components in dairy products will also be presented.

Energy balance, physical activity, and cancer risk

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

Weight, dietary behavior, and physical activity in childhood and adolescence: implications for adult cancer risk

Lifestyle factors related to energy balance, including weight, dietary behavior and physical activity, are associated with cancer risk. The period of childhood and growth into adolescence and early adulthood may re-present a 'cumulative risk' for later adult-onset cancers. We review a number of epidemiologic studies that have examined associations among childhood and adolescent body size, diet, and physical activity with adult cancer risk. These studies suggest that unhealthy behaviors that develop early in life and persist over time may increase the risk of some cancer types, such as premenopausal breast, ovarian, endometrial, colon and renal cancer, adversely affect cancer-related morbidities, and increase mortality. Continued research is needed to further determine and refine how timing and degree of such exposures in early childhood and adolescence relate to adult cancer risk. Presently, sufficient evidence suggests a continued need for stronger primary prevention in cancer and obesity research via modified lifestyle behaviors earlier in the developmental spectrum, i.e. during childhood and adolescence.

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.

Vitamin D and human health: lessons from vitamin D receptor null mice

The vitamin D endocrine system is essential for calcium and bone homeostasis. The precise mode of action and the full spectrum of activities of the vitamin D hormone, 1,25-dihydroxyvitamin D [1,25-(OH)(2)D], can now be better evaluated by critical analysis of mice with engineered deletion of the vitamin D receptor (VDR). Absence of a functional VDR or the key activating enzyme, 25-OHD-1alpha-hydroxylase (CYP27B1), in mice creates a bone and growth plate phenotype that mimics humans with the same congenital disease or severe vitamin D deficiency. The intestine is the key target for the VDR because high calcium intake, or selective VDR rescue in the intestine, restores a normal bone and growth plate phenotype. The VDR is nearly ubiquitously expressed, and almost all cells respond to 1,25-(OH)(2)D exposure; about 3% of the mouse or human genome is regulated, directly and/or indirectly, by the vitamin D endocrine system, suggesting a more widespread function. VDR-deficient mice, but not vitamin D- or 1alpha-hydroxylase-deficient mice, and man develop total alopecia, indicating that the function of the VDR and its ligand is not fully overlapping. The immune system of VDR- or vitamin D-deficient mice is grossly normal but shows increased sensitivity to autoimmune diseases such as inflammatory bowel disease or type 1 diabetes after exposure to predisposing factors. VDR-deficient mice do not have a spontaneous increase in cancer but are more prone to oncogene- or chemocarcinogen-induced tumors. They also develop high renin hypertension, cardiac hypertrophy, and increased thrombogenicity. Vitamin D deficiency in humans is associated with increased prevalence of diseases, as predicted by the VDR null phenotype. Prospective vitamin D supplementation studies with multiple noncalcemic endpoints are needed to define the benefits of an optimal vitamin D status.