Meta-analyses of vitamin D intake, 25-hydroxyvitamin D status, vitamin D receptor polymorphisms, and colorectal cancer risk

Vitamin D receptor gene polymorphisms in relation to the risk of colorectal cancer in the Polish population

The protective effect of vitamin D against several cancers including colorectal cancer is modulated by the vitamin D receptor (VDR) and its ligand, the active form of vitamin D. VDR response has been found to play a role in various genes encoding proteins involved in crucial cellular pathways. Single nucleotide polymorphisms (SNPs) of the VDR gene that modulate its activity are located in the promoter region, exons 2–9, and their vicinity and also in the 3′UTR region. Some of them have been previously studied in relation to cancer susceptibility and prognosis. The aim of our study was to investigate four polymorphisms, BsmI, ApaI, TaqI, and FokI, of the VDR gene in Polish patients with sporadic colorectal cancer and to evaluate their association with susceptibility to cancer. We found a significant association between the BsmI genotype and cancer (individuals with the bb genotype are more susceptible to cancer compared to those with other genotypes, p = 0.025, Fisher’s exact test for 2 × 2 table). Also, the TT genotype at TaqI and the AA genotype at ApaI are correlated with a higher risk of cancer (p = 0.00071 and p = 1.0 × 10⁻⁵, respectively). We found relatively strong linkage disequilibrium between the TaqI and ApaI loci (T with A and t with a, respectively). Both of these loci are associated with cancer. We do not observe any such association for the FokI polymorphism. In conclusion, a small modification in VDR expression may play a role in such a multipathway process as tumorigenesis.

Serum vitamin D, vitamin D binding protein, and risk of colorectal cancer

BACKGROUND

We previously reported a positive association between serum 25-hydroxyvitamin D (25(OH)D) and colorectal cancer risk. To further elucidate this association, we examined the molar ratio of 25(OH)D to vitamin D binding protein (DBP), the primary 25(OH)D transport protein, and whether DBP modified the association between 25(OH)D and colorectal cancer risk.

METHODS

In a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, controls were 1∶1 matched to 416 colorectal cancer cases based on age and date of blood collection. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) for quartiles of 25(OH)D, DBP, and the molar ratio of 25(OH)D:DBP, a proxy for free, unbound circulating 25(OH)D.

RESULTS

Comparing highest to lowest quartiles, DBP was not associated with colorectal cancer risk (OR = 0.91; 95% CI: 0.58, 1.42, p for trend  = 0.58); however, a positive risk association was observed for the molar ratio of 25(OH)D:DBP (OR = 1.44; 95% CI: 0.92, 2.26, p for trend  = 0.04). In stratified analyses, the positive association between 25(OH)D and colorectal cancer was stronger among men with DBP levels above the median (OR = 1.89; 95% CI: 1.07, 3.36, p for trend  = 0.01) than below the median (OR = 1.20; 95% CI: 0.68, 2.12, p for trend  = 0.87), although the interaction was not statistically significant (p for interaction  = 0.24).

CONCLUSION

Circulating DBP may influence the association between 25(OH)D and colorectal cancer in male smokers, with the suggestion of a stronger positive association in men with higher DBP concentrations. This finding should be examined in other populations, especially those that include women and non-smokers.

Plasma vitamin D concentration influences survival outcome after a diagnosis of colorectal cancer

PURPOSE

We investigated whether the plasma level of 25-hydroxyvitamin D (25-OHD) after a diagnosis of colorectal cancer (CRC) influences survival outcome.

PATIENTS AND METHODS

We prospectively studied 1,598 patients with stage I to III CRC. We sought association between plasma 25-OHD and stage-specific survival and tested for interaction between 25-OHD level and variation at the vitamin D receptor (VDR) gene locus. Blood was sampled postoperatively, and plasma was assayed for 25-OHD by liquid chromatography-tandem mass spectrometry. VDR polymorphisms (rs1544410, rs10735810, rs7975232, rs11568820) were genotyped, and haplotypes were inferred by using BEAGLE software. We tested for association between survival and 25-OHD, VDR genotype/haplotype, and after applying a VDR genotype-25-OHD interaction term. We conducted Kaplan-Meier survival analysis and used Cox proportional hazards models to estimate adjusted hazard ratios (HRs).

RESULTS

We found strong associations between plasma 25-OHD concentration and CRC-specific (P = .008) and all-cause mortality (P = .003). Adjusted HRs were 0.68 (95% CI, 0.50 to 0.90) and 0.70 (95% CI, 0.55 to 0.89), respectively (highest v lowest 25-OHD tertile), particularly in stage II disease (HR, 0.44; P = .004 for CRC-specific mortality). We detected gene-environment interactions between 25-OHD concentration and rs11568820 genotype for CRC-specific (P = .008) and all-cause (P = .022) mortality, number of protective alleles (P = .004 and P = .018, respectively), and GAGC haplotype at the VDR locus for all-cause mortality (P = .008).

CONCLUSION

In patients with stage I to III CRC, postoperative plasma vitamin D is associated with clinically important differences in survival outcome, higher levels being associated with better outcome. We observed interactions between 25-OHD level and VDR genotype, suggesting a causal relationship between vitamin D and survival. The influence of vitamin D supplementation on CRC outcome will require further investigation.

BsmI polymorphism of vitamin D receptor gene and cancer risk: a comprehensive meta-analysis

The VDR gene is an important regulator of the vitamin D pathway, and the role of some of its polymorphisms on cancer risk was previously investigated. A trend of cancer risk reduction with the VDR BsmI B allele was observed for many cancer sites. We performed a comprehensive meta-analysis to investigate the role of VDR BsmI polymorphism on cancer risk, even according to different ethnicities. Summary odds ratios (SORs) were calculated with random-effects models and maximum likelihood estimation. We categorized studies into three groups ("moderate", "high" and "very high confidence") according to departure from Hardy-Weinberg equilibrium in controls, reported minor allele frequency and genotyping quality controls. The meta-analysis included 73 studies with 45,218 cases and 52,057 controls. We found a significant 6-7% reduction of cancer risk at any site respectively for carriers of Bb genotype (SOR; 95%CI: 0.94; 0.90-0.99) and for carriers of BsmI BB genotype (SOR; 95%CI: 0.93; 0.89-0.98) compared to bb carriers, and they remain statistically significant when we restricted the analysis to at least "high confidence" studies. For skin cancer, a significant risk reduction was observed for Bb carriers (SOR; 95%CI: 0.86; 0.76-0.98). We also found a significant reduction of colorectal cancer risk for BB and Bb+BB genotypes carriers, but these SORs were no more significant when we restricted the analysis to studies with "high confidence". When the analysis was stratified by ethnicity, we still observed a significant decreased risk for both Bb and BB compared to bb genotype among Caucasians: SORs (95%CI) for any cancer site were 0.97 (0.93-1.00) and 0.95 (0.91-0.99), respectively. Among other ethnic groups the inverse association was still present, but did not reach statistical significance. In conclusion, we suggest a weak effect of BsmI B allele in reducing cancer risk at any site, especially of the skin.

Calcium, vitamin D, dairy products, and mortality among colorectal cancer survivors: the Cancer Prevention Study-II Nutrition Cohort

PURPOSE

Higher calcium, vitamin D, and dairy product intakes are associated with lower colorectal cancer incidence, but their impacts on colorectal cancer survival are unclear. We evaluated associations of calcium, vitamin D, and dairy product intakes before and after colorectal cancer diagnosis with all-cause and colorectal cancer-specific mortality among colorectal cancer patients.

PATIENTS AND METHODS

This analysis included 2,284 participants in a prospective cohort who were diagnosed with invasive, nonmetastatic colorectal cancer after baseline (1992 or 1993) and up to 2009. Mortality follow-up was through 2010. Prediagnosis risk factor information was collected on the baseline questionnaire. Postdiagnosis information was collected via questionnaires in 1999 and 2003 and was available for 1,111 patients.

RESULTS

A total of 949 participants with colorectal cancer died during follow-up, including 408 from colorectal cancer. In multivariable-adjusted Cox proportional hazards regression models, postdiagnosis total calcium intake was inversely associated with all-cause mortality (relative risk [RR] for those in the highest relative to the lowest quartiles, 0.72; 95% CI, 0.53-0.98; Ptrend = .02) and associated with marginally statistically significant reduced colorectal cancer-specific mortality (RR, 0.59; 95% CI, 0.33 to 1.05; Ptrend = .01). An inverse association with all-cause mortality was also observed for postdiagnosis milk intake (RR, 0.72; 95% CI, 0.55 to 0.94; Ptrend = .02), but not vitamin D intake. Prediagnosis calcium, vitamin D, and dairy product intakes were not associated with any mortality outcomes.

CONCLUSION

Higher postdiagnosis intakes of total calcium and milk may be associated with lower risk of death among patients with nonmetastatic colorectal cancer.

Vitamin D supplements and cancer incidence and mortality: a meta-analysis

Background:

Observational studies suggest that effects of vitamin D may be stronger for cancer mortality than for incidence. Yet, existing randomised controlled trials (RCTs) of vitamin D supplementation have limited power to examine the relationships as their primary end points are not cancer incidence or mortality.

Methods:

Meta-analyses of RCTs of vitamin D supplementation and total cancer incidence and mortality were conducted.

Results:

Over 2–7 years of duration, vitamin D supplementations had little effect on total cancer incidence (400–1100 IU per day, summary relative risk (RR)=1.00, 95% confidence interval (CI)=0.94–1.06, I²=0% four RCTs with combined 4333 cases), but significantly reduced total cancer mortality (400–833 IU per day, summary RR=0.88, 95% CI=0.78–0.98, I²=0%, three RCTs with combined 1190 deaths).

Conclusions:

Over 2–7 years of duration, the benefit of vitamin D supplementation may be limited to cancer mortality.

Role of the VDR Bsm I and Apa I polymorphisms in the risk of colorectal cancer in Kashmir

OBJECTIVE

A case-control study aiming to evaluate the relationship between Bsm I and Apa I restriction fragment gene polymorphisms and colorectal cancer (CRC) was carried out in Kashmir, including a total of 368 subjects (180 cases and 188 controls).

METHODS

DNA samples extracted from the blood of the subjects were analyzed for 3' untranslated region (3' UTR) Apa I and Bsm I polymorphisms using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR).

RESULTS

A statistically significant 2.7-fold increased risk was observed in individuals found homozygous for the presence of the 'b' allele, in comparison to subjects homozygous for the 'B' allele (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.49-4.86 (Bsm I)), and a statistically insignificant 2-fold increased risk was found among individuals with the 'aa' genotype, as compared to subjects with the 'AA' genotype (OR 2.017, 95% CI 0.86-4.7). Our study also yielded statistically significant results when the Apa I polymorphism was stratified by age (≤ 50 years) and dwelling area (rural area), and the Bsm I polymorphism by gender (male gender), suggesting a possible role of Apa I and Bsm I polymorphisms in the etiology of CRC in Kashmir.

CONCLUSION

We conclude that Apa I and Bsm I single-nucleotide polymorphisms (SNPs) in the vitamin D receptor gene (VDR) might be associated with susceptibility to CRC among Kashmiris.

The role of vitamin D in reducing cancer risk and progression

Vitamin D is not really a vitamin but the precursor to the potent steroid hormone calcitriol, which has widespread actions throughout the body. Calcitriol regulates numerous cellular pathways that could have a role in determining cancer risk and prognosis. Although epidemiological and early clinical trials are inconsistent, and randomized control trials in humans do not yet exist to conclusively support a beneficial role for vitamin D, accumulating results from preclinical and some clinical studies strongly suggest that vitamin D deficiency increases the risk of developing cancer and that avoiding deficiency and adding vitamin D supplements might be an economical and safe way to reduce cancer incidence and improve cancer prognosis and outcome.

Associations between circulating 1,25(OH)₂D concentration and odds of metachronous colorectal adenoma

Cellular-level studies demonstrate that the availability of the secosteroid hormone 1α,25-dihydroxyvitamin D [1,25(OH)2D] to colon cells promotes anti-carcinogenic activities. Although epidemiological data are relatively sparse, suggestive inverse trends have been reported between circulating 1,25(OH)2D concentration and colorectal neoplasia. We therefore sought to evaluate the relationship between circulating 1,25(OH)2D concentrations and odds for metachronous colorectal adenomas among 1,151 participants from a randomized trial of ursodeoxycholic acid for colorectal adenoma prevention. No relationship between 1,25(OH)2D and overall odds for metachronous lesions was observed, with ORs (95% CIs) of 0.80 (0.60-1.07) and 0.81 (0.60-1.10) for participants in the second and third tertiles, respectively, compared with those in the lowest (p-trend = 0.17). However, a statistically significant inverse association was observed between circulating 1,25(OH)2D concentration and odds of proximal metachronous adenoma, with an OR (95% CI) of 0.71 (0.52-0.98) for individuals in the highest tertile of 1,25(OH)2D compared with those in the lowest (p-trend = 0.04). While there was no relationship overall between 1,25(OH)2D and metachronous distal lesions, there was a significantly reduced odds for women, but not men, in the highest 1,25(OH)2D tertile compared with the lowest (OR 0.53; 95% CI 0.27-1.03; p-trend = 0.05; p-interaction = 0.08). The observed differences in associations with proximal and distal adenomas could indicate that delivery and activity of vitamin D metabolites in different anatomic sites in the colorectum varies, particularly by gender. These results identify novel associations between 1,25(OH)2D and metachronous proximal and distal colorectal adenoma, and suggest that future studies are needed to ascertain potential mechanistic differences in 1,25(OH)2D action in the colorectum.

Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials

OBJECTIVE

To evaluate the breadth, validity, and presence of biases of the associations of vitamin D with diverse outcomes.

DESIGN

Umbrella review of the evidence across systematic reviews and meta-analyses of observational studies of plasma 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D concentrations and randomised controlled trials of vitamin D supplementation.

DATA SOURCES

Medline, Embase, and screening of citations and references.

ELIGIBILITY CRITERIA

Three types of studies were eligible for the umbrella review: systematic reviews and meta-analyses that examined observational associations between circulating vitamin D concentrations and any clinical outcome; and meta-analyses of randomised controlled trials assessing supplementation with vitamin D or active compounds (both established and newer compounds of vitamin D).

RESULTS

107 systematic literature reviews and 74 meta-analyses of observational studies of plasma vitamin D concentrations and 87 meta-analyses of randomised controlled trials of vitamin D supplementation were identified. The relation between vitamin D and 137 outcomes has been explored, covering a wide range of skeletal, malignant, cardiovascular, autoimmune, infectious, metabolic, and other diseases. Ten outcomes were examined by both meta-analyses of observational studies and meta-analyses of randomised controlled trials, but the direction of the effect and level of statistical significance was concordant only for birth weight (maternal vitamin D status or supplementation). On the basis of the available evidence, an association between vitamin D concentrations and birth weight, dental caries in children, maternal vitamin D concentrations at term, and parathyroid hormone concentrations in patients with chronic kidney disease requiring dialysis is probable, but further studies and better designed trials are needed to draw firmer conclusions. In contrast to previous reports, evidence does not support the argument that vitamin D only supplementation increases bone mineral density or reduces the risk of fractures or falls in older people.

CONCLUSIONS

Despite a few hundred systematic reviews and meta-analyses, highly convincing evidence of a clear role of vitamin D does not exist for any outcome, but associations with a selection of outcomes are probable.

Calcium intake and colorectal cancer risk: dose-response meta-analysis of prospective observational studies

Mechanistic and epidemiologic studies provide considerable evidence for a protective association between calcium intake and incident colorectal cancer (CRC). While the relationship has not been substantiated by short-duration randomized controlled trials (RCTs) of CRC, trials do show a benefit on adenomas, a precursor to CRC. To address some of this inconsistency, we conducted dose-response meta-analyses by sources of calcium intake, based on prospective observational studies published up to December 2013 identified from PubMed, Embase, and BIOSIS. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random-effects model. For total calcium intake, each 300 mg/day increase was associated with an approximately 8% reduced risk of CRC (summary RR = 0.92, 95% CI = 0.89-0.95, I(2)  = 47%, 15 studies with 12,305 cases, intake = 250-1,900 mg/day, follow-up = 3.3-16 years). While the risk decreased less steeply in higher range of total calcium intake (P(non-linearity)  = 0.04), the degree of curvature was mild and statistical significance of non-linearity was sensitive to one study. For supplementary calcium, each 300 mg/day increase was associated with an approximately 9% reduced risk of CRC (summary RR = 0.91, 95% CI = 0.86-0.98, I(2)  = 67%, six studies with 8,839 cases, intake = 0-1,150 mg/day, follow-up = 5-10 years). The test for non-linearity was not statistically significant (P(non-linearity)  = 0.11). In conclusion, both dietary and supplementary calcium intake may continue to decrease CRC risk beyond 1,000 mg/day. Calcium supplements and non-dairy products fortified with calcium may serve as additional targets in the prevention of CRC. RCTs of calcium supplements with at least 10 years of follow-up are warranted to confirm a benefit of calcium supplements on CRC risk.

TaqI polymorphism of VDR gene contributes to breast cancer risk

Previous studies on the association of Vitamin D receptor (VDR) TaqI gene polymorphism with breast carcinogenesis have yielded inconsistent and inconclusive findings. The current meta-analysis was performed to provide a more precise assessment on the role of VDR TaqI polymorphism in breast cancer risk. 20 eligible case-control studies involving 9,055 cases and 10,516 controls were identified after a comprehensive literature search of the PubMed, Embase, Web of Science, and Wanfang databases. The pooled odds ratio (OR) with corresponding 95% confidence interval (95% CI) was calculated. Stratified analyses by ethnicity and study quality were conducted for further estimation. All statistical analyses were conducted by use of STATA (STATA Corporation, College Station, TX, Version 11.0). The overall ORs showed that the variant t allele and tt genotype were related to an increased risk of breast cancer (OR(t vs. T) = 1.05, 95% CI 1.01-1.10, P(OR) = 0.025; OR(tt vs. TT) = 1.12, 95% CI 1.03-1.23, P(OR) = 0.011; OR(tt vs. Tt + TT) = 1.10, 95% CI 1.01-1.20, P(OR) = 0.023). Stratified analyses of studies in Caucasians and with high-quality further confirmed the results. However, no significant relationship was observed among Asians. This meta-analysis suggests that the VDR TaqI polymorphism confers risk effect on the breast cancer development, particularly in Caucasians.

Hype versus hope: metformin and vitamin D as anticancer agents

There has been increasing interest in the use of metformin and vitamin D to reduce cancer risk and improve outcomes. Metformin, an oral antidiabetic drug, improves insulin resistance and has been associated with reduced cancer incidence and cancer mortality. Low levels of vitamin D have also been associated with increased cancer risk, mainly in retrospective studies, and it has been suggested that vitamin D supplementation might play a role in cancer prevention. Preclinical data provide a biologic rationale for these associations; however, the human data arise predominantly from observational studies and caution is needed in their translation into clinical practice. This is because of the recognized limitations of observational studies, such as time-related survival biases, selection and referral biases, short follow-up, and the presence of confounding factors that can lead to spurious or inaccurate findings. Combined examination of associations with cancer risk and outcome (occurring when exposure in a population that does not yet have cancer is analyzed in relation to cancer death) may yield results that are difficult to interpret. Finally, associations across all cancers may differ from those in specific cancer types. These shortcomings can be overcome in properly designed and adequately powered prospective randomized trials; however, such trials are both expensive and time consuming. We review the literature examining the associations of metformin and vitamin D with cancer, discussing weakness and strengths and making recommendations for further research and clinical practice.

Meta-analysis of long-term vitamin D supplementation on overall mortality

Introduction

It has been suggested that vitamin D is effective to prevent mortality. However, there is no consistent conclusion that the effects of vitamin D supplementation on all-cause mortality are associated with duration of treatment. We conducted a meta-analysis regarding this issue in an effort to provide a more robust answer.

Methods

A comprehensive search in a number of databases, including MEDLINE, Embase and The Cochrane Central Register of Controlled Trials, was conducted for collecting randomized controlled trials (RCTs) on vitamin D supplementation preventing mortality. Two investigators independently screened the literature according to the inclusive and exclusive criteria and the relative data were extracted. Data analysis was performed by using Review Manager 5.0 software.

Results

Data from forty-two RCT s were included. Vitamin D therapy significantly decreased all-cause mortality with a duration of follow-up longer than 3 years with a RR (95% CI) of 0.94 (0.90–0.98). No benefit was seen in a shorter follow-up periods with a RR (95% CI) of 1.04 (0.97–1.12). Results remain robust after sensitivity analysis. The following subgroups of long-term follow-up had significantly fewer deaths: female only, participants with a mean age younger than 80, daily dose of 800 IU or less, participants with vitamin D insufficiency (baseline 25-hydroxyvitamin D level less than 50 nmol/L) and cholecalciferol therapy. In addition, the combination of vitamin D and calcium significantly reduced mortality and vitamin D alone also had a trend to decrease mortality in a longer time follow up.

Conclusions

The data suggest that supplementation of vitamin D is effective in preventing overall mortality in a long-term treatment, whereas it is not significantly effective in a treatment duration shorter than 3 years. Future studies are needed to identify the efficacy of vitamin D on specific mortality, such as cancer and cardiovascular disease mortality in a long-term treatment duration.

Circulating 25-hydroxyvitamin D serum concentration and total cancer incidence and mortality: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of longitudinal studies on the association of 25(OH)D with total cancer incidence and mortality.

METHOD

Relevant longitudinal observational studies were identified by systematically searching Ovid Medline, EMBASE, and ISI Web of Knowledge databases. Due to the heterogeneity across studies in categorizing 25(OH)D concentration, all results were recalculated for an increase of 25(OH)D by 50 nmol/L.

RESULTS

In meta-analyses with random effects models, the summary risk ratios and confidence intervals (RRs (95% CI)) for the association of an increase of 25(OH)D by 50 nmol/L with total cancer incidence (5 studies) and mortality (13 studies) were 0.89 (0.81, 0.97) and 0.83 (0.71, 0.96), respectively. In sex-specific analyses no significant association with total cancer incidence was observed among men or women. A clear inverse association with total cancer mortality was observed among women (0.76 (0.60, 0.98)) but not among men (0.92 (0.65, 1.32)). Large heterogeneity was observed for studies on total cancer mortality (P<0.01) but not for studies on cancer incidence (P=0.41). No publication bias was found.

CONCLUSION

The meta-analysis suggests a moderate inverse association of 25(OH)D concentration with total cancer incidence and mortality.

Vitamin D receptor and colorectal cancer

Colorectal cancer (CRC) is the third cause of cancer-related morbidity and mortality in America following lung cancer and stomach cancer. In China and other Asian countries, increasingly Westernized diets have led to a high incidence of CRC. The vitamin D receptor (VDR) can mediate 1,25(OH)₂D₃ to regulate cell growth and differentiation in a variety of normal tissues or tumor tissues. VDR gene polymorphisms are closely related to the occurrence and development of CRC. This article summarizes the recent progress in understanding the relationship between VDR and CRC in terms of the structure and function of VDR, mechanisms of CRC inhibition, correlation between VDR polymorphisms and CRC, and the development of analogs of VDR ligands.

Genetic predictors of circulating 25-hydroxyvitamin d and risk of colorectal cancer

BACKGROUND

Experimental evidence has demonstrated an antineoplastic role for vitamin D in the colon, and higher circulating 25-hydroxyvitamin D [25(OH)D] levels are consistently associated with a lower risk of colorectal cancer. Genome-wide association studies have identified loci associated with levels of circulating 25(OH)D. The identified single-nucleotide polymorphisms (SNPs) from four gene regions collectively explain approximately 5% of the variance in circulating 25(OH)D.

METHODS

We investigated whether five polymorphisms in GC, CYP2R1, CYP24A1, and DHCR7/NADSYN1, genes previously shown to be associated with circulating 25(OH)D levels, were associated with colorectal cancer risk in 10,061 cases and 12,768 controls drawn from 13 studies included in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) and Colon Cancer Family Registry (CCFR). We conducted a meta-analysis of crude and multivariate-adjusted logistic regression models to calculate odds ratios and associated confidence intervals for SNPs individually, SNPs simultaneously, and for a vitamin D additive genetic risk score (GRS).

RESULTS

We did not observe a statistically significant association between the 25(OH)D-associated SNPs and colorectal cancer marginally, conditionally, or as a GRS, or for colon or rectal cancer separately.

CONCLUSIONS

Our findings do not support an association between SNPs associated with circulating 25(OH)D and risk of colorectal cancer. Additional work is warranted to investigate the complex relationship between 25(OH)D and colorectal cancer risk.

IMPACT

There was no association observed between genetic markers of circulating 25(OH)D and colorectal cancer. These genetic markers account for a small proportion of the variance in 25(OH)D.

Predicting vitamin D deficiency in older Australian adults

OBJECTIVE

There has been a dramatic increase in vitamin D testing in Australia in recent years, prompting calls for targeted testing. We sought to develop a model to identify people most at risk of vitamin D deficiency.

DESIGN AND PARTICIPANTS

This is a cross-sectional study of 644 60- to 84-year-old participants, 95% of whom were Caucasian, who took part in a pilot randomized controlled trial of vitamin D supplementation.

MEASUREMENTS

Baseline 25(OH)D was measured using the Diasorin Liaison platform. Vitamin D insufficiency and deficiency were defined using 50 and 25 nmol/l as cut-points, respectively. A questionnaire was used to obtain information on demographic characteristics and lifestyle factors. We used multivariate logistic regression to predict low vitamin D and calculated the net benefit of using the model compared with 'test-all' and 'test-none' strategies.

RESULTS

The mean serum 25(OH)D was 42 (SD 14) nmol/1. Seventy-five per cent of participants were vitamin D insufficient and 10% deficient. Serum 25(OH)D was positively correlated with time outdoors, physical activity, vitamin D intake and ambient UVR, and inversely correlated with age, BMI and poor self-reported health status. These predictors explained approximately 21% of the variance in serum 25(OH)D. The area under the ROC curve predicting vitamin D deficiency was 0·82. Net benefit for the prediction model was higher than that for the 'test-all' strategy at all probability thresholds and higher than the 'test-none' strategy for probabilities up to 60%.

CONCLUSION

Our model could predict vitamin D deficiency with reasonable accuracy, but it needs to be validated in other populations before being implemented.

Low 25(OH) vitamin D3 levels are associated with adverse outcome in newly diagnosed, intensively treated adult acute myeloid leukemia

BACKGROUND

Several studies have suggested that low 25(OH) vitamin D3 levels may be prognostic in some malignancies, but no studies have evaluated their impact on treatment outcome in patients with acute myeloid leukemia (AML).

METHODS

Vitamin D levels were evaluated in 97 consecutive, newly diagnosed, intensively treated patients with AML. MicroRNA expression profiles and single nucleotide polymorphisms (SNPs) in the 25(OH) vitamin D3 pathway genes were evaluated and correlated with 25(OH) vitamin D3 levels and treatment outcome.

RESULTS

Thirty-four patients (35%) had normal 25(OH) vitamin D3 levels (32-100 ng/mL), 34 patients (35%) had insufficient levels (20-31.9 ng/mL), and 29 patients (30%) had deficient levels (<20 ng/mL). Insufficient/deficient 25(OH) vitamin D3 levels were associated with worse relapse-free survival (RFS) compared with normal vitamin D3 levels. In multivariate analyses, deficient 25(OH) vitamin D3 , smoking, European Leukemia Network genetic group, and white blood cell count retained their statistical significance for RFS. Several microRNAs and SNPs were associated with 25(OH) vitamin D3 levels, although none remained significant after multiple test corrections; one 25(OH) vitamin D3 receptor SNP, rs10783219, was associated with a lower complete remission rate (P = .0442) and with shorter RFS (P = .0058) and overall survival (P = .0011).

CONCLUSIONS

It remains to be determined what role microRNA and SNP profiles play in contributing to low 25(OH) vitamin D3 level and/or outcome and whether supplementation will improve outcomes for patients with AML.

Social disparities, health risk behaviors, and cancer

BACKGROUND

Overall cancer incidence rates decreased in the most recent time period in both men and women, largely due to improvements in surgical therapeutic approaches (tertiary prevention) and screening programs (secondary prevention), but differences in cancer incidence and survival according to socioeconomic status are documented worldwide. Health risk behaviors, defined as habits or practices that increase an individual's likelihood of harmful health outcomes, are thought to mediate such inequalities.

DISCUSSION

Obesity has been related with increased cancer incidence and mortality due to imbalance of leptin and adiponectin which are connected to activation of PI3K, MAPK, and STAT3 pathways and decreasing insulin/insulin-like growth factor (IGF)-1 and mTOR signaling via activation of 5 AMP-activated protein kinase (AMPK), respectively. Physical activity has been associated to prevent cancer by the aforementioned obesity-related mechanisms, but also increasing level of circulating vitamin D, which has been related to lower risk of several cancers, and increasing prostaglandin F2a and reducing prostaglandin E2, which are both related with cancer prevention and promotion, respectively. A large number of different substances may induce themselves a direct cytotoxicity and mutagenic action on cells by smoking, whereas alcohol promote immune suppression, the delay of DNA repair, inhibition of the detoxification of carcinogens, the production of acetaldehyde, and the contribution to abnormal DNA methylation. The combined smoking and alcohol drinking habits have been shown to increase cancer risk by smoke action of increasing the acetaldehyde burden following alcohol consumption and alcohol action of enhancing the activation of various procarcinogens contained in tobacco smoke.

CONCLUSIONS

Interventions at the social level may be done to increase awareness about cancer risks and promote changing in unhealthy behaviors.

Polymorphisms in the vitamin D receptor gene and the lung cancer risk

The relationship between the vitamin D receptor (VDR) polymorphisms and the susceptibility to lung cancer remains unclear. The present meta-analysis was performed to estimate the polymorphisms of VDR and lung cancer risk. The pooled odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) were calculated. Subgroup analysis by smoking status was carried out for further elucidation. The VDR BsmI polymorphism seemed to be negatively associated with the lung cancer risk (A vs. G, OR = 0.71, 95 % CI, 0.52-0.96; GA vs. GG, OR = 0.54, 95 % CI, 0.35-0.83; AA + GA vs. GG, OR = 0.55, 95 % CI, 0.36-0.84), particularly among the smokers (AA + GA vs. GG, OR = 0.39, 95 % CI, 0.21-0.72). The VDR ApaI variant genotypes did not alter the risk of lung cancer under all gene models in overall analysis. However, smokers carrying the variant G allele were more susceptible to lung cancer (G vs. T, OR = 1.60, 95 % CI, 1.14-2.25). The polymorphism of VDR TaqI was related to a decreased risk of lung cancer (C vs. T, OR = 0.62, 95 % CI, 0.26-1.46; CC vs. TT, OR = 0.44, 95 % CI, 0.21-0.91; TC vs. TT, OR = 0.58, 95 % CI, 0.38-0.90; CC + TC vs. TT, OR = 0.55, 95 % CI, 0.36-0.84). Besides, the CC + TC carriers in the smokers were at a significantly reduced risk of lung cancer (CC + TC vs. TT, OR = 0.48, 95 % CI, 0.16-1.44). The study supports that the polymorphisms of VDR BsmI and TaqI play protective roles in the lung carcinogenesis, particularly among the smokers. The association of VDR ApaI polymorphism with the lung cancer risk needs to be further elucidated.

Oral chemoprevention with acetyl salicylic Acid, vitamin D and calcium reduces the risk of tobacco carcinogen-induced bladder tumors in mice

Bladder cancer is a common urological malignancy with high recurrence rate, which may be reduced by chemoprevention. The aim was to evaluate chemoprevention in a mouse model of tobacco carcinogen-induced bladder tumors. A total of 60 A/J mice were randomized to normal diet, diet with low calcium, and diet with chemoprevention (acetyl salicylic acid, 1-alpha 25(OH)2-vitamin D3 and calcium). There were significantly fewer tumors (0 (0-0) vs. 0 (0-2), p = .045) and fewer animals with tumors (0/20 vs. 5/20, p = .045) in the chemoprevention group compared with controls. Thus, chemoprevention diet effectively reduced the tumor promoting effect of tobacco carcinogens in the mouse bladder.

Association between vitamin D receptor gene Cdx2 polymorphism and breast cancer susceptibility

Vitamin D receptor (VDR) gene polymorphisms have been reported to influence susceptibility to breast cancer. However, published findings on the association between VDR Cdx2 polymorphism and breast cancer susceptibility are conflicting. To get a precise estimation of the association between VDR Cdx2 polymorphism and breast cancer susceptibility, we conducted a meta-analysis of four case-control studies with a total of 8,880 subjects (3,841 cases and 5,039 controls). The results showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer (A versus G: OR = 0.96, 95% CI 0.84-1.09; AA versus GG: OR = 0.97, 95% CI 0.64-1.45; AA/GA versus GG: OR = 0.94, 95% CI 0.80-1.10; AA versus GG/GA: OR = 0.99, 95% CI 0.65-1.51). Subgroup analysis in Caucasians also showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer in Caucasians. However, there was a significant association in Africans (A versus G: OR = 0.75, 95% CI 0.60-0.94; AA versus GG: OR = 0.53, 95% CI 0.29-0.99; AA/GA versus GG: OR = 0.75, 95% CI 0.57-0.97). Therefore, the association between VDR Cdx2 polymorphism and breast cancer susceptibility is only found in Africans. More studies are needed to further assess the association in Asians or Africans.

Model selection approach suggests causal association between 25-hydroxyvitamin D and colorectal cancer

INTRODUCTION

Vitamin D deficiency has been associated with increased risk of colorectal cancer (CRC), but causal relationship has not yet been confirmed. We investigate the direction of causation between vitamin D and CRC by extending the conventional approaches to allow pleiotropic relationships and by explicitly modelling unmeasured confounders.

METHODS

Plasma 25-hydroxyvitamin D (25-OHD), genetic variants associated with 25-OHD and CRC, and other relevant information was available for 2645 individuals (1057 CRC cases and 1588 controls) and included in the model. We investigate whether 25-OHD is likely to be causally associated with CRC, or vice versa, by selecting the best modelling hypothesis according to Bayesian predictive scores. We examine consistency for a range of prior assumptions.

RESULTS

Model comparison showed preference for the causal association between low 25-OHD and CRC over the reverse causal hypothesis. This was confirmed for posterior mean deviances obtained for both models (11.5 natural log units in favour of the causal model), and also for deviance information criteria (DIC) computed for a range of prior distributions. Overall, models ignoring hidden confounding or pleiotropy had significantly poorer DIC scores.

CONCLUSION

Results suggest causal association between 25-OHD and colorectal cancer, and support the need for randomised clinical trials for further confirmations.

Predicted plasma 25-hydroxyvitamin D and risk of renal cell cancer

BACKGROUND

Although the kidney is a primary organ for vitamin D metabolism, the association between vitamin D and renal cell cancer (RCC) remains unclear.

METHODS

We prospectively evaluated the association between predicted plasma 25-hydroxyvitamin D [25(OH)D] and RCC risk among 72,051 women and 46,380 men in the period from 1986 to 2008. Predicted plasma 25(OH)D scores were computed using validated regression models that included major determinants of vitamin D status (race, ultraviolet B flux, physical activity, body mass index, estimated vitamin D intake, alcohol consumption, and postmenopausal hormone use in women). Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. All statistical tests were two-sided.

RESULTS

During 22 years of follow-up, we documented 201 cases of incident RCC in women and 207 cases in men. The multivariable hazard ratios between extreme quintiles of predicted 25(OH)D score were 0.50 (95% CI = 0.32 to 0.80) in women, 0.59 (95% CI = 0.37 to 0.94) in men, and 0.54 (95% CI = 0.39 to 0.75; P trend < .001) in the pooled cohorts. An increment of 10 ng/mL in predicted 25(OH)D score was associated with a 44% lower incidence of RCC (pooled HR = 0.56, 95% CI = 0.42 to 0.74). We found no statistically significant association between vitamin D intake estimated from food-frequency questionnaires and RCC incidence.

CONCLUSION

Higher predicted plasma 25(OH)D levels were associated with a statistically significantly lower risk of RCC in men and women. Our findings need to be confirmed by other prospective studies using valid markers of long-term vitamin D status.

Vitamin D and the epidemiology of upper gastrointestinal cancers: a critical analysis of the current evidence

Prospective analyses have yet to uncover a consistent relationship between vitamin D status and incidence and mortality of rarer cancers including esophageal and upper gastrointestinal cancers. We searched PubMed for literature about the epidemiology of upper gastrointestinal cancers and vitamin D published over the last decade and then summarized and critiqued the results of these studies in this review. The search yielded nine relevant studies. Overall, no consistent relationship was reported between serum vitamin D levels or a surrogate and upper gastrointestinal cancers. Four studies reported negative correlations between vitamin D status and upper gastrointestinal cancer, three reported positive correlations, one reported no correlation, and one reported both positive and negative correlations. No relationship has been established on the basis of epidemiologic data, but studies examining sun exposure consistently report an inverse association with esophageal cancer. The current literature is limited by the methods used to assess vitamin D status, lack of specific data for the types of upper gastrointestinal cancer, and failure to establish a temporal relationship between vitamin D status assessment and presentation of upper gastrointestinal cancer. It is possible that the lack of a consistent relationship is a consequence of inaccurate and imprecise assessment of vitamin D status.

rs12512631 on the group specific complement (vitamin D-binding protein GC) implicated in melanoma susceptibility

BACKGROUND

Solar radiation should be avoided in melanoma patients. Nevertheless, this is the main means by which the body produces vitamin D. Evidence suggests a protective role against cancer for vitamin D. Since vitamin D performs its function by binding the receptor encoded by the vitamin D-receptor gene (VDR), most studies have focused on polymorphisms (SNPs) within this gene. However, the gene encoding the vitamin D-binding protein (GC) appears in recent studies as a major player in the role of a serum vitamin D level regulator and in Cutaneous Melanoma (CM) predisposition.

METHODS

We performed a case-control study of 12 polymorphisms on GC and 9 on VDR among 530 cases and 314 controls from Spanish population.

RESULTS

We found association between SNP rs12512631, located 3'downstream of GC, and risk of CM that seems to fit a dominant model (OR 1.63 95%CI 1.23-2.17 p-value 7×10(-4)). This association remained Bonferroni's correction and after adjustment for potential confounders (p-value 3×10(-3)) and even after increasing the sample size to 1729 individuals (p-value 0.0129). Moreover, we confirmed evidence of an association between CM susceptibility and the linkage disequilibrium block marked by tag-SNP rs222016 (p-value 0.032). This block covers the GC intron 1 region, with probable regulatory functions.

CONCLUSION

To our knowledge, this is the first vitamin D pathway-related polymorphism study in melanoma risk conducted in the Spanish population. Furthermore, we show an association between polymorphisms in GC and melanoma risk, confirming recent studies in different populations.

Nonlinear association between magnesium intake and the risk of colorectal cancer

OBJECTIVES

The association between dietary magnesium intake and the risk of colorectal cancer has been examined by many prospective studies, but remains controversial because of inconsistent results. We aimed to carry out a meta-analysis to investigate this.

MATERIALS AND METHODS

We assessed this association with categorical and dose-response meta-analysis of data from prospective cohort studies. Relevant studies were identified by searching MEDLINE, EMBASE, and OVID for studies published before 9 June 2012, with no restrictions. Relative risks (RRs) and 95% confidence intervals (CIs) for the highest versus lowest and dose-response association were estimated using random-effects models. Heterogeneity and publication bias was investigated, and subgroup, sensitivity, and meta-regression analyses were carried out.

RESULTS

The analysis included 333 510 participants with 7435 colorectal cancers from seven prospective cohort studies. The summary RR for the highest versus the lowest intake of dietary magnesium was 0.81 (95% CI: 0.70-0.92) for colorectal cancer, 0.76 (95% CI: 0.64-0.88) for colon cancer, and 0.82 (95% CI: 0.58-1.06) for rectal cancer. For men and women, the pooled RR was 0.76 (95% CI: 0.51-1.01) and 0.81 (95% CI: 0.68-0.94), respectively. Significant inverse associations of colorectal cancer and dietary magnesium emerged in nonlinear models (p nonlinearity=0.03). The greatest risk reduction was observed when dietary magnesium intake increased from very low levels.

CONCLUSION

Dietary magnesium intake has a statistically significant nonlinear inverse association with the risk of colorectal cancer. The greatest reduction for magnesium intake is 200-270 mg/day. Whether the association is causal or because of confounding warrants further investigation.

Diet and colorectal cancer risk and survival

SUMMARY Unhealthy dietary and other lifestyle factors account for 20–45% of all colorectal cancer cases. Being overweight or obese, having a high intake of red and processed meat and alcohol increase the risk of colorectal cancer, while a high intake of dairy products, fruits and vegetables, foods containing dietary fiber and being physically active lower the risk of colorectal cancer. There are only a limited number of studies available on diet and outcomes in colorectal cancer survivors. Most of these studies are retrospective in nature, and are small in size, which makes it difficult to draw conclusions. However, the available studies to date putatively suggest that lifestyle factors lowering the risk of colorectal cancer are also beneficial for cancer survivors.

Health benefits of seafood; is it just the fatty acids?

There is a considerable body of literature suggesting a wide range of health benefits associated with diets high in seafood. However, the demand for seafood across the world now exceeds that available from capture fisheries. This has created a rapidly increasing market for aquaculture products, the nutrient composition of which is dependent on feed composition. The use of fishmeal in this food chain does little to counteract the environmental impact of fisheries and so the on-going development of alternative sources is to be welcomed. Nevertheless, an in-depth understanding as to which nutrients in seafood provide benefit is required to permit the production of foods of maximal health benefit to humans. This paper reviews our current knowledge of the beneficial nutrient composition of seafood, in particular omega-3 fatty acids, selenium, taurine, vitamins D and B12, in the context of the development of environmentally sustainable aquaculture.

Nutritional agents with anti-inflammatory properties in chemoprevention of colorectal neoplasia

The strong link between inflammation and colorectal carcinogenesis provides the rationale for using anti-inflammatory agents for chemoprevention of colorectal cancer (CRC). Several naturally occurring substances with anti-inflammatory properties, used in a purified 'nutraceutical' form, including omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and polyphenols such as curcumin and resveratrol, have been demonstrated to have anti-CRC activity in preclinical models. As expected, these agents have an excellent safety and tolerability profile in Phase II clinical trials. Phase III randomized clinical trials of these naturally occurring substances are now beginning to be reported. The omega-3 polyunsaturated fatty acid EPA, in the free fatty acid (FFA) form, has been demonstrated to reduce adenomatous polyp number and size in patients with familial adenomatous polyposis (FAP), a finding which has prompted evaluation of this formulation of EPA for prevention of 'sporadic' colorectal neoplasia. Anti-inflammatory 'nutraceuticals' require further clinical evaluation in polyp prevention trials as they exhibit many of the characteristics of the ideal cancer chemoprevention agent, including safety, tolerability and patient acceptability.

Is prevention of cancer by sun exposure more than just the effect of vitamin D? A systematic review of epidemiological studies

The number of studies reporting on the association between sunlight exposure, vitamin D and cancer risk is steadily increasing. We reviewed all published case-control and cohort studies concerning colorectal-, prostate-, breast cancer, non-Hodgkin's lymphoma (NHL) and both sunlight and vitamin D to update our previous review and to verify if the epidemiological evidence is in line with the hypothesis that the possible preventive effect of sunlight on cancer might be mediated not only by vitamin D but also by other pathways. We found that almost all epidemiological studies suggest that chronic (not intermittent) sun exposure is associated with a reduced risk of colorectal-, breast-, prostate cancer and NHL. In colorectal- and to a lesser degree in breast cancer vitamin D levels were found to be inversely associated with cancer risk. In prostate cancer and NHL, however, no associations were found. These findings are discussed and it is concluded that the evidence that sunlight is a protective factor for colorectal-, prostate-, breast cancer and non-Hodgkin's lymphoma is still accumulating. The same conclusion can be drawn concerning high vitamin D levels and the risk of colorectal cancer and possibly breast cancer. Particularly in prostate cancer and NHL other sunlight potentiated and vitamin D independent pathways, such as modulation of the immune system and the circadian rhythm, and the degradation of folic acid might play a role in reduced cancer risk as well.

Association between ambient ultraviolet radiation and risk of esophageal cancer

OBJECTIVES

Ecological studies have suggested an inverse relationship between latitude and risks of some cancers. However, associations between solar ultraviolet radiation (UVR) exposure and esophageal cancer risk have not been fully explored. We therefore investigated the association between nevi, freckles, and measures of ambient UVR over the life-course with risks of esophageal cancers.

METHODS

We compared estimated lifetime residential ambient UVR among Australian patients with esophageal cancer (330 esophageal adenocarcinoma (EAC), 386 esophago-gastric junction adenocarcinoma (EGJAC), and 279 esophageal squamous cell carcinoma (ESCC)), and 1471 population controls. We asked people where they had lived at different periods of their life, and assigned ambient UVR to each location based on measurements from NASA's Total Ozone Mapping Spectrometer database. Freckling and nevus burden were self-reported. We used multivariable logistic regression models to estimate the magnitude of associations between phenotype, ambient UVR, and esophageal cancer risk.

RESULTS

Compared with population controls, patients with EAC and EGJAC were less likely to have high levels of estimated cumulative lifetime ambient UVR (EAC odds ratio (OR) 0.59, 95% confidence interval (CI) 0.35-0.99, EGJAC OR 0.55, 0.34-0.90). We found no association between UVR and risk of ESCC (OR 0.91, 0.51-1.64). The associations were independent of age, sex, body mass index, education, state of recruitment, frequency of reflux, smoking status, alcohol consumption, and H. pylori serostatus. Cases with EAC were also significantly less likely to report high levels of nevi than controls.

CONCLUSIONS

These data show an inverse association between ambient solar UVR at residential locations and risk of EAC and EGJAC, but not ESCC.

Current progress in using vitamin D and its analogs for cancer prevention and treatment

Vitamin D has long been known for its physiological role in mineral homeostasis through its actions on the intestines, kidneys, parathyroid glands and bone. However, recent observations of antiproliferative, prodifferentiating and antiangiogenic effects elicited by the bioactive form of vitamin D (1,25[OH](2)D(3)) in a broad range of cancers is less well understood. Here, we review the increasing epidemiological and experimental evidence that supports the development of 1,25(OH)(2)D(3) and vitamin D analogs as preventative and therapeutic anticancer agents. Furthermore, this review summarizes the preclinical and clinical studies of vitamin D and its analogs over the past decade, indicating the current problems of dose-limiting toxicity from hypercalcemia and large interpatient variability in pharmacokinetics. A better understanding of how genetic variants influence vitamin D status should not only improve cancer risk predictions, but also promote the development of vitamin D analogs with more specific actions to improve therapeutic outcomes.

Plasma 25-hydroxyvitamin D(3) and bladder cancer risk according to tumor stage and FGFR3 status: a mechanism-based epidemiological study

BACKGROUND

Previous evidence suggests that 25-hydroxyvitamin D(3) [25(OH)D(3)] protects against several cancers. However, little is known regarding urothelial bladder cancer (UBC). We analyzed the association between plasma 25(OH)D(3) and overall risk of UBC, as well as according to stage and FGFR3 molecular subphenotypes.

METHODS

Plasma concentrations of 25(OH)D(3) in 1125 cases with UBC and 1028 control subjects were determined by a chemiluminescence immunoassay. FGFR3 mutational status and expression in tumor tissue were assessed. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by logistic regression adjusting for potential confounders. Analyses were further stratified by tumor invasiveness and grade, FGFR3 expression, and smoking status. Cell proliferation was measured in human UBC cell lines cultured with 1α,25-dihydroxyvitamin D(3).

RESULTS

A statistically significantly increased risk of UBC was observed among subjects presenting the lowest concentrations of 25(OH)D(3) (OR(adj) = 1.83; 95% CI = 1.19 to 2.82; P = .006), showing a dose-response effect (P (trend) = .004). The association was stronger for patients with muscle-invasive tumors, especially among low-FGFR3 expressers (OR(adj) = 5.94; 95% CI = 1.72 to 20.45; P = .005). The biological plausibility of these associations is supported by the fact that, in vitro, 1α,25-dihydroxyvitamin D(3) upregulates FGFR3 expression in UBC cell lines with low levels of wild-type FGFR3.

CONCLUSION

These findings support a role of vitamin D in the pathogenesis of UBC and show that 25(OH)D(3) levels are associated with FGFR3 expression in the tumor. Because FGFR3 mutation and overexpression are markers of better outcome, our findings suggest that individuals with low levels of plasma 25(OH)D(3) may be at high risk of more aggressive forms of UBC.

D-livering the message: the importance of vitamin D status in chronic liver disease

Vitamin D is synthesized predominantly in the liver and functions as an important secosteroid hormone with pleiotropic effects. While its key regulatory role in calcium and bone homeostasis is well established, recently there is increasing recognition that vitamin D also regulates cell proliferation and differentiation, and has immunomodulatory, anti-inflammatory and anti-fibrotic properties. These non-skeletal effects are relevant in the pathogenesis and treatment of many causes of chronic liver disease. Vitamin D deficiency is frequently present in chronic liver disease and may predict non-response to antiviral therapy in chronic hepatitis C. Small studies suggest that vitamin D supplementation improves sustained viral response rates, while 1α-hydroxylase polymorphisms and vitamin D-binding protein are also implicated in therapeutic outcomes. Vitamin D deficiency also closely relates to the severity of non-alcoholic fatty liver disease (NAFLD) and is implicated in the pathogenesis of insulin resistance, a key factor in the development of NAFLD. In preclinical studies, phototherapy and vitamin D supplementation ameliorate NAFLD histopathology, while vitamin D is a powerful anti-fibrotic against thioacetamide liver injury. In liver transplant recipients severe vitamin D deficiency predicts, and vitamin D supplementation prevents, acute cellular rejection. The role of vitamin D in the activation and regulation of both innate and adaptive immune systems may explain its importance in the above liver diseases. Further prospective studies are therefore warranted to investigate the therapeutic impact of vitamin D supplementation in chronic liver disease.

Hyperinsulinemia, insulin resistance, vitamin D, and colorectal cancer among whites and African Americans

African Americans have the highest incidence and mortality rates of colorectal cancer among all US racial and ethnic groups. Dietary factors, lifestyle factors, obesity, variability in screening rates, socioeconomic differences, barriers to screening, and differences in access to health care may be contributory factors to racial and ethnic disparities. African Americans are more likely to demonstrate microsatellite instability in their colorectal tumors leading to malignancy. However, these differences do not completely explain all the variances. Ample evidence implicates insulin resistance and its associated conditions, including elevated insulin and insulin-like growth factor-1 (IGF-1), in colorectal carcinogenesis. African Americans have a high risk for and a high prevalence of insulin resistance and subsequent overt type 2 diabetes. Recent clinical studies revealed that ethnic differences between whites and African Americans in early diabetes-related conditions including hyperinsulinemia already exist during childhood. African Americans have a much higher prevalence of vitamin D deficiency than whites throughout their life spans. Vitamin D deficiency has been associated with higher rates of diabetes and colorectal cancer, particularly in individuals with high serum insulin and IGF-1 levels. Moreover, African Americans have lower insulin sensitivity in tissues, independent of obesity, fat distribution, and inflammation. Further development of measures of biomarkers of tumor biology and host susceptibility may provide further insight on risk stratification in African Americans.

Vitamin D and Major Chronic Illness

OBJECTIVE

To review the current literature regarding vitamin D insufficiency and supplementation in major illnesses.

DESIGN AND METHODS

We reviewed Pubmed-indexed, English language manuscripts from January, 2003 to June, 2012 using search terms related to vitamin D, all-cause mortality, cardiovascular disease, pulmonary disease, diabetes mellitus, and cancer.

OUTCOME MEASURES

Incidence of disease, risk ratios associated with 25-hydroxyvitamin D [25(OH)D] levels, and/or vitamin D supplementation schedules were documented.

RESULTS

Although 25(OH)D levels ≥20 ng/mL were often associated with improved health outcomes, evidence suggests that 25(OH)D levels ≥30 ng/mL may confer additional health benefits.

CONCLUSIONS

Based on the available evidence, vitamin D supplementation to restore 25(OH)D levels within a range of 30-50 ng/mL is reasonable in order to optimize potential benefits and minimize potential risks. This, of course, should be considered in the context of individual patient needs and co-morbidities.

Vitamins, minerals, essential fatty acids and colorectal cancer risk in the United Kingdom Dietary Cohort Consortium

The risk for colorectal cancer may be influenced by the dietary intake of various vitamins, minerals and essential fatty acids. We conducted a pooled analysis of dietary data collected using food diaries in seven prospective studies in the United Kingdom Dietary Cohort Consortium. Five hundred sixty-five cases of colorectal cancer were matched with 1,951 controls on study centre, age, sex and recruitment date. Dietary intakes of retinol, vitamin A, thiamin, riboflavin, vitamin B6, folate, vitamin B12, vitamin D, calcium, iron, magnesium, potassium, n - 6 fatty acids, n - 3 fatty acids and the ratio of n - 6 to n - 3 fatty acids were estimated and their associations with colorectal cancer examined using conditional logistic regression models, adjusting for exact age, height, weight, energy intake, alcohol intake, fiber intake, smoking, education, social class and physical activity. There were no statistically significant associations between colorectal cancer risk and dietary intake of any of the vitamins, minerals or essential fatty acids examined.

1α,25-Dihydroxyvitamin D3 modulates the interaction between immune and colon cancer cells

Following observations indicating the existence of a relationship between immune and cancer cells in the course of tumor development, it was the aim of the study to establish the role of 1α,25-dihydroxyvitamin D3 (vit. D) in the functional equilibrium between cells from two human colon carcinoma lines-induced cytokine production by peripheral blood mononuclear cells (PBMC). PBMC were incubated with HT-29 and RKO human colon cancer cells with and without vit. D at final concentrations of 10⁻⁸, 10⁻⁷ or 10⁻⁶ M. The production of the cytokines TNF-α, IL-6 and IL-10, as well as the effect of the vitamin on tumor cell proliferation were evaluated. Incubation of PBMC with either HT-29 or RKO cells caused a significant stimulation of both pro- and anti-inflammatory cytokine generation. Addition of vit. D to the incubation mixture containing PBMC and cells of both colon carcinoma lines caused a marked inhibition of the generation of the pro-inflammatory cytokines TNF-α and IL-6 and to a lesser extent-of the IL-10. Vit. D did not affect the proliferation of the cancer cells. The results indicate the existence of a functional "dialog" between immune and cancer cells expressed by an alteration of their capacity for cytokine production and support the role of inflammation in carcinogenesis. The ability of vit. D to attenuate production of the pro-inflammatory cytokines when added to the incubation mixture containing PBMC and cancer cells endorses observations as for the beneficial role of the vitamin in suppressing inflammation with subsequent colon cancer prevention.

An exploratory analysis of common genetic variants in the vitamin D pathway including genome-wide associated variants in relation to glioma risk and outcome

PURPOSE

Experimental and epidemiological evidence shows a beneficial role of vitamin D in cancer. In vitro evidence is consistent with a similar protective function in glioma; however, no study has yet examined the potential role of vitamin D in glioma.

METHODS

We evaluated the association between common genetic variants in the vitamin D pathway and glioma risk and patient outcome in 622 newly diagnosed glioma cases and 628 healthy controls enrolled in a clinic-based case-control study. Subjects were genotyped for 7 candidate and tagging single nucleotide polymorphisms in the vitamin D receptor and 8 additional variants in NADSYN1, GC, CYP24A1, CYP2R1, and C10ORF88 linked in genome-wide association studies to serum concentrations of vitamin D. Unconditional logistic regression was used to estimate age- and gender-adjusted odds ratios and 95 % confidence intervals for glioma risk according to vitamin D genotypes. Proportional hazards regression was used to estimate hazard ratios for glioma-related death among 320 patients diagnosed with high-grade tumors. P values were uncorrected for multiple comparisons.

RESULTS

Risk of astrocytic tumors was associated with variant alleles in rs3829251 (NADSYN1), rs10741657 (CYP2R1), rs2228570 (Fok1, VDR), and rs731236 (Taq1, VDR). No risk associations were found among oligodendroglial tumors. Survival associations were observed according to variant status for rs1544410 (Bsm1, VDR) and rs6013897 (CYP24A1).

CONCLUSION

This exploratory analysis provides limited evidence of a role for genetic variation in vitamin D pathway genes with glioma risk and survival.

Instrumental variable estimation of the causal effect of plasma 25-hydroxy-vitamin D on colorectal cancer risk: a mendelian randomization analysis

Vitamin D deficiency has been associated with several common diseases, including cancer and is being investigated as a possible risk factor for these conditions. We reported the striking prevalence of vitamin D deficiency in Scotland. Previous epidemiological studies have reported an association between low dietary vitamin D and colorectal cancer (CRC). Using a case-control study design, we tested the association between plasma 25-hydroxy-vitamin D (25-OHD) and CRC (2,001 cases, 2,237 controls). To determine whether plasma 25-OHD levels are causally linked to CRC risk, we applied the control function instrumental variable (IV) method of the mendelian randomization (MR) approach using four single nucleotide polymorphisms (rs2282679, rs12785878, rs10741657, rs6013897) previously shown to be associated with plasma 25-OHD. Low plasma 25-OHD levels were associated with CRC risk in the crude model (odds ratio (OR): 0.76, 95% Confidence Interval (CI): 0.71, 0.81, p: 1.4×10(-14)) and after adjusting for age, sex and other confounding factors. Using an allele score that combined all four SNPs as the IV, the estimated causal effect was OR 1.16 (95% CI 0.60, 2.23), whilst it was 0.94 (95% CI 0.46, 1.91) and 0.93 (0.53, 1.63) when using an upstream (rs12785878, rs10741657) and a downstream allele score (rs2282679, rs6013897), respectively. 25-OHD levels were inversely associated with CRC risk, in agreement with recent meta-analyses. The fact that this finding was not replicated when the MR approach was employed might be due to weak instruments, giving low power to demonstrate an effect (<0.35). The prevalence and degree of vitamin D deficiency amongst individuals living in northerly latitudes is of considerable importance because of its relationship to disease. To elucidate the effect of vitamin D on CRC cancer risk, additional large studies of vitamin D and CRC risk are required and/or the application of alternative methods that are less sensitive to weak instrument restrictions.