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

Vitiligo and Prostate Cancer Correlation

A 72-year-old male with a history of systemic hypertension, asthma, chronic obstructive pulmonary disease (COPD), and hyperlipidemia presents with diffuse patches of cutaneous depigmentation. A shave biopsy of different regions of depigmented skin indicated vitiligo. The patient was prescribed Opzelura (ruxolitinib) 1.5% topical cream as well as tacrolimus 0.1% topical ointment for vitiligo. He also had a history of prostate cancer. A prostate biopsy revealed three sites of prostatic adenocarcinoma with a Gleason score of 6 and a Prostate Imaging-Reporting and Data System (PI-RADS) score of 2. The patient remained in active surveillance for prostate cancer without treatment, due to its low severity. A subsequent biopsy five years later revealed a decrease in prostate cancer prevalence, with cancer present in only one core and at a lower severity. The purpose of this case presentation is to discuss possible links between vitiligo and prostate cancer, as well as their shared mechanisms and pathways.

Vitamin D and potential effects on cancers: a review

Cancer is characterized by the abnormal and uncontrollable division and growth of cells that can infiltrate tissues and alter normal physiological function, which will become crucial and life-threatening if left untreated. Cancer can be a result of genetics, such as mutations or environmental causes, including smoking, lack of physical activity, as well as nutritional imbalance in the body. Vitamin D is one of the foremost nutrients that play a crucial role in a variety of biochemical pathways, and it is an important key factor in several diseases. Vitamin D is an essential nutrient for preventing malignancies and a complementary treatment for cancer through direct and indirect biochemical pathways. In this article, we summarized the correlation between vitamin D and various cancers using an extensive search on PubMed, Google Scholar, and Scopus. This paper reviews the role of vitamin D in different types of cancer.

A long non-coding RNA as a direct vitamin D target transcribed from the anti-sense strand of the human HSD17B2 locus

Vitamin D (VD) exerts a wide variety of actions via gene regulation mediated by the nuclear vitamin D receptor (VDR) under physiological and pathological settings. However, the known target genes of VDR appear unlikely to account for all VD actions. We used in silico and transcriptomic approaches in human cell lines to search for non-coding RNAs transcriptionally regulated by VD directly. Four long non-coding RNAs (lncRNAs), but no microRNAs (miRNAs), were found, supported by the presence of consensus VDR-binding motifs in the coding regions. One of these lncRNAs (AS-HSD17β2) is transcribed from the antisense strand of the HSD17β2 locus, which is also a direct VD target. AS-HSD17β2 attenuated HSD17β2 expression. Thus, AS-HSD17β2 represents a direct lncRNA target of VD.

Ex vivo Vitamin D supplementation improves viscoelastic profiles in prostate cancer patients

BACKGROUND: Increased risk of thromboembolic events is associated with prostate cancer, specifically linked to activation of tissue factor. Vitamin D has potential anticoagulant effects by the downregulation of tissue factor expression. OBJECTIVES: To evaluate the effects on clot formation, the morphological and viscoelastic profiles of prostate cancer patients, before and after ex vivo supplementation of Vitamin D was studied. METHODS: Participants were recruited into a metastatic, non-metastatic and reference group. Whole blood samples were treated ex vivo with a dose of 0.5μg/kg Calcitriol. Clot kinetics were assessed using Thromboelastography ®. Morphology of the blood components were studied using scanning electron microscopy (SEM). RESULTS: Results from the Thromboelastography ® and SEM indicated no major differences between the non-metastatic group before and after treatment compared to the reference group. The Thromboelastography ® showed that the metastatic group had an increased viscoelastic profile relating to a hypercoagulable state. Visible changes with regards to platelet activation and fibrin morphology were demonstrated with SEM analysis of the metastatic group. The viscoelastic and morphological properties for the non-metastatic group after treatment improved to be comparable to the reference group. CONCLUSION: Vitamin D supplementation may lead to a more favorable viscoelastic profile, with less dangerous clots forming.

Reduced risk of skin cancer and internal malignancies in vitiligo patients: a retrospective population-based cohort study in Taiwan

The relationship between cancer and vitiligo has been explored but with inconsistent results. To examine the long-term cancer risk in vitiligo patients, we conducted a retrospective nationwide cohort study. From the National Health Insurance Research Database of Taiwan, a total of 13,824 vitiligo patients were identified and matched with 55,296 reference subjects without vitiligo by age, gender, and propensity score estimated by major comorbidities from 1997 to 2013. Demographic characteristics and comorbidities were compared between these two groups. Incidence rate ratios and hazard ratios (HRs) were calculated to examine cancer risks. The 16-year incidence rates of overall cancers were 621.06 (566.56–675.55) and 726.99 (697.24–756.74) per 100,000 person-years in the vitiligo and reference groups. Patients with vitiligo showed a significantly decreased risk of overall cancers [adjusted HR, 0.85; 95% confidence interval (CI), 0.77 to 0.93, p < 0.001] compared with reference subjects without vitiligo after adjusting for age, sex, comorbidities, and treatments. The risks of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) were significantly reduced (adjusted HR 0.21, 95% CI 0.11–0.38, p < 0.001), as well as internal malignancies (adjusted HR 0.89, 95% CI 0.81–0.99, p = 0.026). The results were consistent across different subgroups of patients, including male gender, ages more than 40 years, and those receiving long-term systemic disease-modifying antirheumatic drugs and phototherapies. Information related to phenotype, disease duration, vitiligo lesion sites, family history of vitiligo or cancer, occupation, and personal lifestyle was not included in the database. Vitiligo is associated with reduced risks of BCC and SCC, as well as internal malignancies.

Potential Role of Natural Products to Combat Radiotherapy and Their Future Perspectives

Cancer is the second leading cause of death in the world. Chemotherapy and radiotherapy (RT) are the common cancer treatments. In addition to these limitations, the development of adverse effects from chemotherapy and RT reduces the quality of life for cancer patients. Cellular radiosensitivity, or the ability to resist and overcome cell damage caused by ionizing radiation (IR), is directly related to cancer cells' response to RT. Therefore, radiobiological research is emphasizing chemical compounds 'radiosensitization of cancer cells so that they are more reactive in the IR spectrum. Recent years researchers have seen an increase in interest in natural products that have antitumor effects with minimal side effects. Natural products, on the other hand, are easy to recover and therefore less expensive. There have been several scientific studies done based on these compounds that have tested their ability in vitro and in vivo to induce tumor radiosensitization. The role of natural products in RT, as well as their usefulness and potential applications, is the goal of this current review.

The Association Between the Genetic VDR SNP c.907+75C>T and Prostate Cancer Risk Is Modified by Tanning Potential

BACKGROUND

Prostate cancer (PCa) is a multifactorial disease involving complex interactions between genetic and physiological/environmental factors. Vitamin D receptor (VDR) plays a role in numerous cellular pathways and it has been suggested that VDR genetic variants influence individual susceptibility to PCa.

MATERIALS AND METHODS

Logistic regression analysis was used to assess the association of six VDR single nucleotide polymorphisms (SNPs) and factors such as tanning potential and UV sunlight exposure with PCa risk.

RESULTS

Marginal significant interactions were found, with a 2-fold increase risk of PCa between SNP 1 (c.278-69G>A) and sunlight UV exposure [odds ratio (OR)=2.02, 95% confidence intervaI (CI)=1.036-4.36; p=0.05]; and a 4-fold increase risk of PCa between SNP 4 (c.907+75C>T) and tanning potential (OR=4.40, 95% CI=0.89-29.12; p=0.0591). In contrast, SNP 5 (rs731236, TaqI) and tanning potential interaction had a protective effect by reducing the risk of PCa by 55% (β=-0.804; OR=0.448, 95% CI=0.197-9.42; p=0.0427). SNPs 2 (rs61614328) and 6 (rs533037428) did not show any association with PCa even in the presence of UV sunlight exposure.

CONCLUSION

The protective effect of SNP 4 from PCa is lost and modified by tanning potential in African Americans. This finding needs to be verified by larger studies in different ethnic populations.

COVID-19 fatalities, latitude, sunlight, and vitamin D

Background

Since Vitamin D is known to be vital in regulating the immune system, and sunlight UV radiation exposure on the skin produces Vitamin D and UV intensity is highest nearest the equator, a study was done to examine the correlation between the latitude and COVID-19 fatality rates for countries.

Methods

Eighty-eight countries were selected based on their likelihood of providing reliable data. Using death rates/million for each country from the “worldometer” website, a correlation analysis was done between death rates and a country's latitude.

Results

A highly significant, positive correlation was found between lower death rates and a country's proximity to the equator (Pearson r = 0.40 P < .0001, 2-tailed t test). The R squared of 0.16 means that 16% of the variation in death rates among nations is accounted for by the latitude of the country. Evidence is presented suggesting a direct correlation between sunlight exposure and reduced mortality.

Discussion

This study is the first to document a statistically significant correlation between a country's latitude and its COVID-19 mortality and is consistent with other research regarding latitude, Vitamin D deficiency, and COVID-19 fatalities. Limitations of this study are noted.

Conclusions

Further research is needed to confirm the correlation between latitude and COVID-19 fatalities, and to determine the optimum amounts of safe sunlight exposure and/or vitamin D oral supplementation to reduce COVID-19 fatalities in populations that are at high risk for vitamin D deficiency.

Altered expression of cytochrome P450 enzymes involved in metabolism of androgens and vitamin D in the prostate as a risk factor for prostate cancer

Prostate cancer is the most common malignant disease among men. The signaling pathways, regulated by the androgen and vitamin D receptors, play a key role in prostate cancer. The intracellular level of androgens and vitamin D determines not only receptor functionality, but also the efficacy of cellular processes regulated by them (cell proliferation, apoptosis, differentiation etc.). It is known that several androgen-metabolizing P450s (CYP3A4/5/43 and CYP2B6) and P450 enzymes (CYP2R1, CYP27A1, CYP27B1, CYP24A1, CYP3A4, CYP2J2), which are necessary for vitamin D metabolism, are expressed in the prostate. It was shown that alterations in an expression pattern of the certain cytochrome P450s might lead to the development of castration-resistant cancer (CYP3A4, CYP2J2, CYP24A1), and to chemo-resistance (CYP3A4, CYP3A5, CYP2B6) and early mortality (CYP2B6, CYP27A1, CYP24A1). Moreover, steroidogenic CYPs (CYP17A1, CYP11A1) are not expressed in normal prostate tissue. Alterations in their expression levels in steroidogenic tissues are closely associated with carcinogenesis, and, most importantly, with the development of aggressive forms of prostate cancer. Hence, it is important, to study how expression of CYPs in the prostate might be regulated, to understand the mechanisms of disease development and to improve the effectiveness of therapy. Several CYPs (CYP3A43, CYP2B6, CYP27A1, CYP24A1) can be considered as prognostic and diagnostic markers of prostate cancer. To propose personalized treatment, individual differences in CYP expression should be taken into account.

Active vitamin D induces gene-specific hypomethylation in prostate cancer cells developing vitamin D resistance

Prostate cancer (PCa) is a leading cause of cancer death in men. Despite the antiproliferative effects of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] on PCa, accumulating evidence indicates that 1,25(OH)2D3 promotes cancer progression by increasing genome plasticity. Our investigation of epigenetic changes associated with vitamin D insensitivity found that 1,25(OH)2D3 treatment reduced the expression levels and activities of DNA methyltransferases 1 and 3B (DNMT1 and DNMT3B, respectively). In silico analysis and reporter assay confirmed that 1,25(OH)2D3 downregulated transcriptional activation of the DNMT3B promoter and upregulated microRNAs targeting the 3'-untranslated regions of DNMT3B. We then profiled DNA methylation in the vitamin D-resistant PC-3 cells and a resistant PCa cell model generated by long-term 1,25(OH)2D3 exposure. Several candidate genes were found to be hypomethylated and overexpressed in vitamin D-resistant PCa cells compared with vitamin D-sensitive cells. Most of the identified genes were associated with mammalian target of rapamycin (mTOR) signaling activation, which is known to promote cancer progression. Among them, we found that inhibition of ribosomal protein S6 kinase A1 (RPS6KA1) promoted vitamin D sensitivity in PC-3 cells. Furthermore, The Cancer Genome Atlas (TCGA) prostate cancer data set demonstrated that midline 1 (MID1) expression is positively correlated with tumor stage. Overall, our study reveals an inhibitory mechanism of 1,25(OH)2D3 on DNMT3B, which may contribute to vitamin D resistance in PCa.

The Role of Nuclear Receptors in Prostate Cancer

The nuclear receptor (NR) superfamily consists of 48 members that are divided into seven subfamilies. NRs are transcription factors that play an important role in a number of biological processes. The NR superfamily includes androgen receptor, which is a key player in prostate cancer pathogenesis, suggesting the functional roles of other NRs in prostate cancer. The findings on the roles of NRs in prostate cancer thus far have shown that several NRs such as vitamin D receptor, estrogen receptor β, and mineralocorticoid receptor play antioncogenic roles, while other NRs such as peroxisome proliferator-activated receptor γ and estrogen receptor α as well as androgen receptor play oncogenic roles. However, the roles of other NRs in prostate cancer remain controversial or uninvestigated. Further research on the role of NRs in prostate cancer is required and may lead to the development of novel preventions and therapeutics for prostate cancer.

Cancer Risks in Vitiligo Patients: A Nationwide Population-Based Study in Taiwan

Vitiligo is an autoimmune disease characterized by destruction of melanocytes and associated with other autoimmune disease. Whether the dysregulation of immune system enhances oncogenesis or not remains obscure. Until now, no nationwide population-based study has been conducted regarding this. As such, this paper aims to clarify cancer risk in vitiligo patients. A retrospective nationwide population-based cohort study between 2000 and 2010 was performed based on data from the National Health Insurance Research Database of Taiwan. Standardized incidence ratios (SIRs) of cancers were analyzed. Among the 12,391 vitiligo patients (5364 males and 7027 females) and 48,531.09 person-years of observation, a total of 345 cancers were identified. Significantly increased SIRs were observed for prostate cancer in male patients, thyroid cancer and breast cancer in female patients and bladder cancers in both male and female patients. Unfortunately, the low incidence rate of certain cancers limited the power of our statistical analyses. This study demonstrated the patterns of malignancies in vitiligo patients of Taiwan. Compared with the general population, male patients had higher risks of prostate cancer and female patients had higher risks of thyroid cancer and breast cancer. The risks of bladder cancer were also increased in both male and female patients.

DHPLC Elution Patterns of VDR PCR Products Can Predict Prostate Cancer Susceptibility in African American Men

BACKGROUND/AIM

Denaturing high-performance liquid chromatography (DHPLC) is a technique that is used to detect mutations. The aim of the present study was to determine whether DHPLC elution patterns of vitamin D receptor (VDR) gene PCR products can serve as indicators of susceptibility to prostate cancer (PCa) risk.

MATERIALS AND METHODS

DNA samples of PCa cases and controls were screened for mutations and/or polymorphisms in coding exons of VDR gene using DHPLC analysis. Logistic regression, phi-coefficient (ϕ), and Backward Wald models were used to analyze the data.

RESULTS

Similar elution patterns of exons 1, 6, 7 and 9 along with higher prevalence of heteroduplex DNA were observed in PCa samples than in controls. Exons 4 and 8 had highly significant protective effects (p<0.05). Whereas, exons 5, 7, and 9 were perfectly positively correlated with PCa risk (ϕ=1), thus presenting candidate exons significantly associated with susceptibility to PCa.

CONCLUSION

DHPLC elution patterns of the selected exons could be useful to predict susceptibility to develop PCa.

Occupational exposure to solar ultraviolet radiation and the risk of prostate cancer

OBJECTIVES

Preventable risk factors for prostate cancer are poorly understood; sun exposure is a possible protective factor. The goal of this study was to investigate prostate cancer risk in outdoor workers, a population with high sun exposure.

METHODS

Prostate cancer cases and controls from a large study (conducted between 1994 and 1997) were used for this analysis. A job exposure matrix (JEM) was used to assign solar ultraviolet radiation (UVR) at work as moderate (2 to <6 hours outside/day) or high (≥6 hours). Average daily satellite UV-B measures were linked to the latitude/longitude of the residences of each participant. Several other exposure metrics were also examined, including ever/never exposed and standard erythemal dose by years (SED×years). Logistic regression was used to evaluate the association between solar UVR exposure and the odds of prostate cancer.

RESULTS

A total of 1638 cases and 1697 controls were included. Men of Indian and Asian descent had reduced odds of prostate cancer (ORs 0.17 (0.08 to 0.35) and 0.25 (0.15 to 0.41), respectively) compared with Caucasian men, as did single men (OR 0.76 (0.58 to 0.98)) compared with married men. Overall, no statistically significant associations were observed between sun exposure and prostate cancer with 1 exception. In the satellite-enhanced JEM that considered exposure in high category jobs only, prostate cancer odds in the highest quartile of cumulative exposure was decreased compared with unexposed men (OR 0.68 (0.51 to 0.92)).

CONCLUSIONS

This study found limited evidence for an association with prostate cancer, with the exception of 1 statistically significant finding of a decreased risk among workers with the longest term and highest sun exposure.

Association between Plasma 25-Hydroxyvitamin D, Ancestry and Aggressive Prostate Cancer among African Americans and European Americans in PCaP

BACKGROUND

African Americans (AAs) have lower circulating 25-hydroxyvitamin D3 [25(OH)D3] concentrations and higher prostate cancer (CaP) aggressiveness than other racial/ethnic groups. The purpose of the current study was to examine the relationship between plasma 25(OH)D3, African ancestry and CaP aggressiveness among AAs and European Americans (EAs).

METHODS

Plasma 25(OH)D3 was measured using LC-MS/MS (Liquid Chromatography Tandem Mass Spectrometry) in 537 AA and 663 EA newly-diagnosed CaP patients from the North Carolina-Louisiana Prostate Cancer Project (PCaP) classified as having either 'high' or 'low' aggressive disease based on clinical stage, Gleason grade and prostate specific antigen at diagnosis. Mean plasma 25(OH)D3 concentrations were compared by proportion of African ancestry. Logistic regression was used to calculate multivariable adjusted odds ratios (OR) and 95% confidence intervals (95%CI) for high aggressive CaP by tertile of plasma 25(OH)D3.

RESULTS

AAs with highest percent African ancestry (>95%) had the lowest mean plasma 25(OH)D3 concentrations. Overall, plasma 25(OH)D3 was associated positively with aggressiveness among AA men, an association that was modified by calcium intake (ORT 3vs.T1: 2.23, 95%CI: 1.26-3.95 among men with low calcium intake, and ORT 3vs.T1: 0.19, 95%CI: 0.05-0.70 among men with high calcium intake). Among EAs, the point estimates of the ORs were <1.0 for the upper tertiles with CIs that included the null.

CONCLUSIONS

Among AAs, plasma 25(OH)D3 was associated positively with CaP aggressiveness among men with low calcium intake and inversely among men with high calcium intake. The clinical significance of circulating concentrations of 25(OH)D3 and interactions with calcium intake in the AA population warrants further study.

The association between pre-treatment serum 25-hydroxyvitamin D and survival in newly diagnosed stage IV prostate cancer

Background/Aims

Emerging evidence in the literature suggests a positive association between serum 25-hydroxyvitamin D [25(OH)D], a standard indicator of vitamin D status, and survival in certain types of cancer. We investigated this relationship in newly diagnosed stage IV prostate cancer patients.

Methods

A consecutive cohort of 125 newly diagnosed stage IV prostate cancer patients underwent a baseline serum 25(OH)D evaluation prior to receiving any treatment at our institution between January 2008 and December 2011. We used the vitamin D categories of “deficient (<20 ng/ml)”, “insufficient (20 to 32 ng/ml)”, and “sufficient (>32 ng/ml)”. Cox regression was used to evaluate the prognostic significance of serum 25(OH)D after adjusting for relevant confounders.

Results

Mean age at diagnosis was 60 years. Of the 125 patients, 32 (25.6%) were deficient, 49 (39.2%) were insufficient and 44 (35.2%) were sufficient in vitamin D at the time of diagnosis. The median survival in deficient, insufficient and sufficient cohorts was 47.8, 44.0 and 52.6 months respectively (p = 0.60). On univariate analysis, four variables demonstrated a statistically significant association with survival: nutritional status, bone metastasis, corrected serum calcium and serum albumin (p<0.05 for all). On multivariate analysis, five variables demonstrated statistically significant associations with survival: hospital location, age, bone metastasis, serum albumin and corrected serum calcium (p<0.05 for all). Serum vitamin D status was not significant on either univariate or multivariate analysis.

Conclusion

Contrary to previously published research, we found no significant association between pre-treatment serum 25(OH)D and survival in newly diagnosed stage IV prostate cancer patients. The lack of a significant association between serum vitamin D and survival in our study could perhaps be due to the fact that the disease was far too advanced in our patients for vitamin D levels to have any impact on prognosis.

Baseline serum 25-hydroxyvitamin d levels in men undergoing radical prostatectomy: is there an association with adverse pathologic features?

INTRODUCTION/BACKGROUND

The purpose of this study was to evaluate the prevalence of vitamin D (VitD) deficiency in men undergoing radical prostatectomy and determine whether an association exists between preoperative VitD levels and adverse pathologic features.

PATIENTS AND METHODS

Patients scheduled to undergo radical prostatectomy for clinically localized disease from January to August 2012 were prospectively followed and those with available preoperative serum 25-hydroxyvitamin D levels were included. Men with a known diagnosis of VitD deficiency or taking VitD supplementation were excluded. Cox regression analysis was performed to determine whether preoperative VitD level is predictive of adverse pathologic outcomes.

RESULTS

One hundred consecutive men were included. Mean age was 62 (range, 42-79) years and mean VitD level was 26 (range, 6-57) ng/mL. Overall, 65 men (65%) had suboptimal levels of VitD (< 30 ng/mL), and 32 (32%) had deficiency (< 20 ng/mL). There was no significant correlation between VitD and age (P = .5). In logistic regression analysis, VitD level was not predictive of pathologic Gleason (P = .11), pathologic stage (P = .7), or positive margin status (P = .8).

CONCLUSION

The association between VitD and prostate cancer has been controversial and data suggesting an increased risk of aggressive cancer in men with low levels of VitD have been inconsistent. We found that baseline preoperative VitD level was not associated with any adverse pathologic features. However, VitD deficiency is a common finding in this population, although unrelated to patient age. These results represent the first time the correlation between VitD and prostate cancer has been evaluated in a cohort of men undergoing radical prostatectomy.

Circulating 25-hydroxyvitamin D, vitamin D-binding protein and risk of prostate cancer

We recently reported a significant positive association between 25-hydroxyvitamin D [25(OH)D], the accepted biomarker of vitamin D status, and prostate cancer risk. To further elucidate this association, we examined the influence of vitamin D-binding protein (DBP), the primary transporter of vitamin D compounds in the circulation. Prediagnostic serum concentrations of DBP were assayed for 950 cases and 964 matched controls with existing 25(OH)D measurements within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish men. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), and statistical tests were two sided. Serum DBP modified the association between serum 25(OH)D and prostate cancer, with higher risk for elevated 25(OH)D levels observed primarily among men having DBP concentrations above the median (OR = 1.81, 95% CI: 1.18-2.79 for highest vs. lowest quintile, p-trend = 0.001) compared to those with DBP below the median (OR = 1.22, 95% CI: 0.81-1.84, p-trend 0.97; p-interaction = 0.04). Serum DBP was not associated with prostate cancer risk overall (OR = 0.96, 95% CI: 0.70-1.33 for highest vs. lowest quintile); however, high serum DBP was associated with significantly decreased risk of prostate cancer in men with lower ( Collapse

Key Words

• vitamin d binding protein
• 25-hydroxyvitamin d
• prostate cancer
• serum biomarkers
• prospective study

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MESH Headings

• Adult
• Aged
• Humans
• Male
• Middle Aged
• Odds Ratio
• Prostatic Neoplasms/blood
• Prostatic Neoplasms/epidemiology
• Risk
• Vitamin D/analogs & derivatives
• Vitamin D/blood
• Vitamin D-Binding Protein/blood

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Grants

• N01-RC-45035 CCR NIH HHS
• ZIA CP010195 Intramural NIH HHS
• HHSN261200800001C NCI NIH HHS
• ZIA CP010195-06 Intramural NIH HHS
• HHSN261201000006C NCI NIH HHS
• N01RC37004 CCR NIH HHS
• N01 CN045165 NCI NIH HHS
• HHSN261200800001E NCI NIH HHS

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Affiliation(s)

Stephanie J. Weinstein Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892
Alison M. Mondul Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892
William Kopp Clinical Support Laboratory, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702
Helen Rager Clinical Support Laboratory, SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702
Jarmo Virtamo Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
Demetrius Albanes Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, 20892

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Sun exposure and the risk of prostate cancer in the Singapore Prostate Cancer Study: a case-control study

BACKGROUND

Most of the epidemiology studies on the effects of sun exposure and prostate cancer were conducted among the temperate countries of North America and Europe. Little is known about the influence on Asian populations. The purpose of current study was to evaluate any association of sun exposure with risk of prostate cancer in Chinese, Malays and Indians who reside in the tropics.

METHODS

The Singapore Prostate Cancer Study is a hospital-based case-control study of 240 prostate cancer incident cases and 268 controls conducted in Singapore between April 2007 and May 2009. Detailed information on outdoor activities in the sun, skin colour, sun sensitivity and other possible risk factors were collected in personal interviews. Cases were further classified by Gleason scores and TNM staging. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis, adjusted for age, ethnicity, education, family history of any cancers, BMI and skin colour.

RESULTS

We found that prostate cancer risk was increased in subjects with black/dark-brown eyes (OR 5.88, 95%CI 3.17-10.9), darker skin colour e.g. tan/dark brown/black (OR 7.62, 95%CI 3.41-17.0), frequent sunburn in lifetime (OR 4.30, 95%CI 1.7-11.2) and increased general sun exposure in adulthood per week (OR 2.03, 95%CI 1.09-3.81). The increased risk was consistent for high grade tumours and advanced stage prostate cancers.

CONCLUSION

The findings from this study suggest that excessive sun exposure is a risk factor for prostate cancer in Asians.

Natural compounds as anticancer agents: Experimental evidence

Cancer prevention research has drawn much attention worldwide. It is believed that some types of cancer can be prevented by following a healthy life style. Cancer chemoprevention by either natural or synthetic agents is a promising route towards lowering cancer incidence. In recent years, the concept of cancer chemoprevention has evolved greatly. Experimental studies in animal models demonstrate that the reversal or suppression of premalignant lesions by chemopreventive agents is achievable. Natural occurring agents such as dietary phytochemicals, tea polyphenols and resveratrol show chemopreventive activity in animal models. Moreover, clinical trials for testing the safety and efficacy of a variety of natural agents in preventing or treating human malignancy have been ongoing. Here, we summarize experimental data on the chemopreventive or tumor suppressive effects of several natural compounds including curcumin, (-)-epigallocatechin-3-gallate, resveratrol, indole-3-carbinol, and vitamin D.

Vitamin D and cancer

Vitamin D system is a complex pathway that includes precursors, active metabolites, enzymes, and receptors. This complex system actives several molecular pathways and mediates a multitude of functions. In addition to the classical role in calcium and bone homeostasis, vitamin D plays "non-calcemic" effects in host defense, inflammation, immunity, and cancer processes as recognized in vitro and in vivo studies. The aim of this review is to highlight the relationship between vitamin D and cancer, summarizing several mechanisms proposed to explain the potential protective effect of vitamin D against the development and progression of cancer. Vitamin D acts like a transcription factor that influences central mechanisms of tumorigenesis: growth, cell differentiation, and apoptosis. In addition to cellular and molecular studies, epidemiological surveys have shown that sunlight exposure and consequent increased circulating levels of vitamin D are associated with reduced reduced occurrence and a reduced mortality in different histological types of cancer. Another recent field of interest concerns polymorphisms of vitamin D receptor (VDR); in this context, preliminary data suggest that VDR polymorphisms more frequently associated with tumorigenesis are Fok1, Bsm1, Taq1, Apa1, EcoRV, Cdx2; although further studies are needed to clarify their role in the cancer. In this review, the relationship between vitamin D and cancer is discussed.

Dairy products and cancer

Cancer is a group of more than 100 diseases in which cells display uncontrolled growth, invasion, and sometimes metastasis. Milk and dairy products contain micronutrients and several bioactive constituents that may influence cancer risk and progression. Much of the focus of human, population-based studies has been on the effects of intake of milk and total dairy products or of calcium intake. Based on a systematic review of the epidemiologic literature, the World Cancer Research Fund and American Institute for Cancer Research report concluded there was a probable association between milk intake and lower risk of colorectal cancer, a probable association between diets high in calcium and increased risk of prostate cancer, and limited evidence of an association between milk intake and lower risk of bladder cancer. For other cancers, the evidence was mixed or lacking. Since the 2007 report, several additional, large-cohort studies have been published, including two that show an inverse association between intake of cultured dairy products and bladder cancer. Little is known about the potential effect of various bioactives produced during rumen microbe metabolism on cancer risk. Furthermore, studies support a role of live microbes present in some dairy products in the modulation of the human gut microbial community and gut metabolism. Given the growing appreciation for the role of the gut microbial community in relation to immune function and health and disease, including cancer, the potential role of various dairy products in the modulation of the human gut microbiome warrants further evaluation. Key teaching points: As a dietary exposure, dairy products are a complex group of foods and composition varies by region, which makes evaluation of their association with disease risk difficult. For most cancers, associations between cancer risk and intake of milk and dairy products have been examined only in a small number of cohort studies, and data are inconsistent or lacking. Meta-analyses of cohort data available to date support an inverse association between milk intake and risk of colorectal and bladder cancer and a positive association between diets high in calcium and risk of prostate cancer. Other constituents of dairy products, such as rumen-derived metabolites, have not been evaluated extensively for cancer-preventive properties. The influence of live microbes in fermented dairy products and certain cheeses on the human gut microbiome and immune function is a growing area of study.

Vitamin d, sunlight and prostate cancer risk

Prostate cancer is the second common cancer in men worldwide. The prevention of prostate cancer remains a challenge to researchers and clinicians. Here, we review the relationship of vitamin D and sunlight to prostate cancer risk. Ultraviolet radiation of the sunlight is the main stimulator for vitamin D production in humans. Vitamin D's antiprostate cancer activities may be involved in the actions through the pathways mediated by vitamin D metabolites, vitamin D metabolizing enzymes, vitamin D receptor (VDR), and VDR-regulated genes. Although laboratory studies including the use of animal models have shown that vitamin D has antiprostate cancer properties, whether it can effectively prevent the development and/or progression of prostate cancer in humans remains to be inconclusive and an intensively studied subject. This review will provide up-to-date information regarding the recent outcomes of laboratory and epidemiology studies on the effects of vitamin D on prostate cancer prevention.

Vitamin D receptor protein expression in tumor tissue and prostate cancer progression

PURPOSE

Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies.

PATIENTS AND METHODS

We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI.

RESULTS

Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression.

CONCLUSION

High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.

[Non dietetic environmental risk factors in prostate cancer]

INTRODUCTION

The aim is to update and disclose the main environmental risk factors, excluding dietary factors, involved in the etiopathology of prostate cancer.

MATERIALS AND METHOD

Bibliographic review of the last 25 years of non-dietary environmental risk factors associated with prostate cancer between 1985 and 2010, obtained from MedLine, CancerLit, Science Citation Index and Embase. The search profiles were Environmental Risk Factors/Tobacco/Infectious-Inflammatory Factors/Pesticides/Vasectomy/Occupational Exposures/Chemoprevention Agents/Radiation and Prostate Cancer.

RESULTS

While some non-dietary environmental risk factors increase the risk of acquiring the disease, others decrease it. Of the former, it is worth mentioning exposal to tobacco smoke, chronic infectious-inflammatory prostatic processes and occupational exposure to cadmium, herbicides and pesticides. The first factors that reduce the risk are the use of chemopreventive drugs (Finasterida, Dutasteride) and exposure to ultraviolet solar radiation. With the current data, a vasectomy does not influence the risk of developing the disease.

CONCLUSIONS

The slow process of prostate carcinogenesis is the final result of the interaction of constitutional risk and environmental factors. Non-dietary environmental factors play an important role in the etiopathology of this disease. To appropriately assess the risk factors, extensive case studies that include all the possible variables must be analysed.

Requirements for Vitamin D Across the Life Span

Adequate provision of vitamin D has been found, in ecological, cross-sectional, and observational studies, to be associated with reduction in the risk of many types of cancer, cardiovascular diseases (CVDs), autoimmune diseases, diabetes mellitus types 1 and 2, neurological disorders, several bacterial and viral infections, and adverse pregnancy outcomes in addition to the classical bone disorders of rickets and osteomalacia. Furthermore, investigators have found adequate repletion and increased intakes of vitamin D to be associated with reduced all-cause mortality rates. These findings have been supported by the limited number of properly conducted randomized controlled trials (RCTs) that used more than 400 IU/day of vitamin D. This review presents an overview of the role of vitamin D for the promotion of health for the more important vitamin D-related diseases and conditions. Serum 25-hydroxyvitamin D concentrations of 30—60 ng/ml, corresponding to oral intake or skin production of 1,000—4,000 IU/day of vitamin D, appear necessary in adults for avoidance of hypovitaminosis D-related ill health. People of all ages are encouraged to obtain more vitamin D from judicious exposure to sunshine (for ultraviolet B [UVB] irradiation) or from regular vitamin D supplements because dietary sources do not provide sufficient vitamin D to prevent any health risks other than those of rickets and osteomalacia.

Role of vitamin d in the prevention of pancreatic cancer

Pancreatic cancer is a malignancy of poor prognosis which is mostly diagnosed at advanced stages. Current treatment modalities are very limited creating great interest for novel preventive and therapeutic options. Vitamin D seems to have a protective effect against pancreatic cancer by participating in numerous proapoptotic, antiangiogenic, anti-inflammatory, prodifferentiating, and immunomodulating mechanisms. 25-hydroxyvitamin D [25(OH)D] serum concentrations are currently the best indicator of vitamin D status. There are three main sources of vitamin D: sun exposure, diet,and dietary supplements. Sun exposure has been associated with lower incidence of pancreatic cancer in ecological studies. Increased vitamin D levels seem to protect against pancreatic cancer, but caution is needed as excessive dietary intake may have opposite results. Future studies will verify the role of vitamin D in the prevention and therapy of pancreatic cancer and will lead to guidelines on adequate sun exposure and vitamin D dietary intake.

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.

Assessing vitamin D status: pitfalls for the unwary

The use of vitamin D testing has grown rapidly in the recent times as a result of increased interest in the role of vitamin D in health. Although the generally accepted measure of vitamin D status is circulating 25(OH)D concentration, there is little consensus on which assay method should be used. Commonly used assays include competitive protein-binding assay, RIA, enzyme immunoassay, chemiluminescence immunoassays, HPLC, and LC-MS/MS, each with its own advantages and disadvantages. However, there is significant interassay and interlaboratory variability in measurements. Our simulation of the published data showed that using a deficiency cut-point of 50 nmol/L, 57% of samples assessed using a chemiluminescence immunoassay were classified as deficient compared with 41% of samples assessed using LC-MS/MS; a 20% misclassification rate. Similar rates of misclassification were seen at 75 nmol/L. This has implications for clinical practice and decision limits for vitamin D supplementation, suggesting that cut-points should be assay specific rather than universal and that greater harmonization between laboratories is required. Newer assays using alternative biological samples to determine the circulating 25(OH)D have been proposed and advances in the genetics of vitamin D and the role of vitamin D-binding protein may improve future assay accuracy.

Novel targets for prostate cancer chemoprevention

Among many endocrine-related cancers, prostate cancer (PCa) is the most frequent male malignancy, and it is the second most common cause of cancer-related death in men in the United States. Therefore, this review focuses on summarizing the knowledge of molecular signaling pathways in PCa because, in order to better design new preventive strategies for the fight against PCa, documentation of the knowledge on the pathogenesis of PCa at the molecular level is very important. Cancer cells are known to have alterations in multiple cellular signaling pathways; indeed, the development and the progression of PCa are known to be caused by the deregulation of several selective signaling pathways such as the androgen receptor, Akt, nuclear factor-kappaB, Wnt, Hedgehog, and Notch. Therefore, strategies targeting these important pathways and their upstream and downstream signaling could be promising for the prevention of PCa progression. In this review, we summarize the current knowledge regarding the alterations in cell signaling pathways during the development and progression of PCa, and document compelling evidence showing that these are the targets of several natural agents against PCa progression and its metastases.

Relation between prediagnostic serum 25-hydroxyvitamin D level and incidence of breast, colorectal, and other cancers

The evidence is increasing that higher serum 25-hydroxyvitamin D [25(OH)D] levels reduce the risk of many types of cancer. Ecological and observational studies yield the strongest evidence, with support from studies of mechanisms. A key question is identifying the relation between serum 25(OH)D level and cancer incidence. Meta-analyses of such studies is a reasonable approach to determine the serum 25(OH)D level-cancer incidence relation. This paper reports new meta-analyses for breast and colorectal cancers. Currently, the journal literature offers seven prospective breast cancer and ten prospective colorectal cancer studies that can be used. The data for these studies graphed and compared. Data from some of the studies were multiplied by factors to bring all the studies into reasonable agreement with a tentative dose-response relation. The data were fit with a variety of functions; the best fits were nonlinear functions that tended to asymptotically reach a lower odds ratio at higher serum 25(OH)D levels. These analyses estimated that the 50% reduction in incidence occurs for a value of 78 nmol/L compared with the value at 24 nmol/L for breast cancer, and a value of 60 nmol/L compared with the value at 15 nmol/L for colorectal cancer. Although these results are reasonable, some concern exists that a single serum 25(OH)D level, measured years prior to diagnosis of cancer, does not adequately represent the serum levels for the entire period before diagnosis. Future prospective studies should include more serum 25(OH)D level measurements during the study course.

An ecological study of cancer mortality rates in the United States with respect to solar ultraviolet-B doses, smoking, alcohol consumption and urban/rural residence

The Cohort Consortium Vitamin D Polling Project of Rarer Cancers (VDPP ) study failed to find a beneficial role of prediagnostic serum 25-hydroxyvitamin D [25(OH)D] levels on risk of seven types of rarer cancer: endometrial, esophageal, gastric, kidney, ovarian and pancreatic cancer and non-Hodgkin's lymphoma (NHL). However, ecological studies and studies of oral vitamin D intake have generally found solar ultraviolet B (UVB) and oral vitamin D inversely correlated with incidence and/or mortality rates of these cancers. To explore the discrepancy, I conducted an ecological study of cancer mortality rates for white Americans in the United States for 1950-1994 with data for 503 state economic areas in multiple linear regression analyses with respect to UVB for July, lung cancer, alcohol consumption and urban/rural residence. UVB was significantly inversely correlated with six types of cancer (not pancreatic cancer) in both periods. However, the adjusted R(2) values were much lower for cancers with lower mortality rates than those in an earlier ecological study that used state-averaged data. This finding suggests that the VDPP study may have had too few cases. Thus, the VDPP study should not be considered as providing strong evidence against the solar UVB-vitamin D-cancer hypothesis.

Vitamins and prostate cancer risk

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

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.

Critique of the U-shaped serum 25-hydroxyvitamin D level-disease response relation

Previous work has suggested an optimal serum 25-hydroxyvitamin D [25(OH)D] level near 20-30 ng/mL, above which disease risk may increase. Although based primarily on a prostate cancer study in Nordic countries, examples include esophageal, and pancreatic cancer, cardiovascular disease, and all-cause mortality rate. However, these studies apparently are not representative of the findings in the literature for these diseases or disease outcome in general. The prostate cancer study was from Nordic countries and used serum 25(OH)D levels from more than 15 years prior to cancer diagnosis for about half of the cases. Most studies of prediagnostic serum 25(OH)D find no significant correlation with risk of prostate cancer. Many risk-modifying factors for prostate cancer exist that observational studies generally do not include. The esophageal cancer data were from a region of China with high incidence of esophageal cancer. The pancreatic study was conducted on smokers in Finland. Both the esophageal and pancreatic studies are at odds with many ecological and observational studies in various countries. When several studies for cardiovascular disease, and all-cause mortality rate are combined in preliminary meta-analyses, the best fits to the data show a monotonic decrease of hazard ratio with increasing logarithm of serum 25(OH)D. Thus, little support exists for the U-shaped serum 25(OH)D level-disease response relation, and the few studies that do should not be used in forming public health policies regarding vitamin D and ultraviolet-B irradiance.