Both high and low levels of blood vitamin D are associated with a higher prostate cancer risk: a longitudinal, nested case-control study in the Nordic countries

Vitamin D-related genes, serum vitamin D concentrations and prostate cancer risk

We systematically investigated the association of 48 SNPS in four vitamin D metabolizing genes [CYP27A1, GC, CYP27B1 and CYP24A1] with serum 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] levels and the association of these SNPS and an additional 164 SNPS in eight downstream mediators of vitamin D signaling [VDR, RXRA, RXRB, PPAR, NCOA1, NCOA2, NCOA3 and SMAD3] with prostate cancer risk in the 749 incident prostate cancer cases and 781 controls of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. 25(OH)D (all cases and controls) and 1,25(OH)(2)D (a subset of 150 controls) levels were measured by radioimmunoassay and SNP data were genotyped as part of a genome-wide scan. Among investigated SNPS, only four tag SNPS in GC, the major serum 25(OH)D carrier, were associated with 25(OH)D levels; no SNPS were associated with 1,25(OH)(2)D levels. None of the 212 SNPS examined were associated with cancer risk overall. Among men in the lowest tertile of serum 25(OH)D (<48.9 nmol/l), however, prostate cancer risk was related to tag SNPS in or near the 3' untranslated region (UTR) of VDR, with the strongest association for rs11574143 [odds ratio (95% confidence interval) for risk allele carriers versus wild-type: 2.49 (1.51-4.11), P = 0.0007]; the genotype associations were null among men in tertile 2 and tertile 3. Results from the most comprehensive evaluation of serum vitamin D and its related genes to date suggest that tag SNPS in the 3' UTR of VDR may be associated with risk of prostate cancer in men with low vitamin D status.

Vitamin D and aging

Recent studies using genetically modified mice, such as FGF23-/- and Klotho-/- mice that exhibit altered mineral homeostasis due to a high vitamin D activity showed features of premature aging that include retarded growth, osteoporosis, atherosclerosis, ectopic calcification, immunological deficiency, skin and general organ atrophy, hypogonadism and short lifespan. The phenotype reversed by normalizing vitamin D and/or mineral homeostasis. Thus, hypervitaminosis D due to an increased 1alpha-hydroxylase activity seems to be a cause of the premature aging. In several studies, we have described that a complete or partial lack of vitamin D action (VDR-/- mice and CYP27B1-/-) show almost similar phenotype as FGF23-/- or Klotho-/- mice. VDR mutant mice have growth retardation, osteoporosis, kyphosis, skin thickening and wrinkling, alopecia, ectopic calcification, progressive loss of hearing and balance as well as short lifespan. CYP27B1-/- mice do not show alopecia nor balance deficit, which might be apoVDR-dependent or calcidiol-dependent. The features are typical to premature aging. The phenotype is resistant to a normalization of the mineral homeostasis by a rescue diet containing high calcium and phosphate. Taken together, aging shows a U-shaped dependency on hormonal forms of vitamin D suggesting that there is an optimal concentration of vitamin D in delaying aging phenomena. Our recent study shows that calcidiol is an active hormone. Since serum calcidiol but not calcitriol is fluctuating in physiological situations, calcidiol might determine the biological output of vitamin D action. Due to its high serum concentration and better uptake of calcidiol-DBP by the target cells through the cubilin-megalin system, calcidiol seems to be an important circulating hormone. Therefore, serum calcidiol might be associated with an increased risk of aging-related chronic diseases more directly than calcitriol. Aging and cancer seem to be tightly associated phenomena. Accumulation of damage on DNA and telomeres cause both aging and cancer, moreover the signalling pathways seem to converge on tumour suppressor protein, p53, which seems to be regulated by vitamin D. Also, the insulin-like growth factor signalling pathway (IGF-1, IGFBPs, IGFR) and fibroblast growth factor-23 (FGF-23) regulate growth, aging and cancer. Vitamin D can regulate these signalling pathways, too. Also NF-kappaB and telomerase reverse transcriptase (TERT) might be molecular mechanisms mediating vitamin D action in aging and cancer. Calcidiol serum concentrations show a U-shaped risk of prostate cancer suggesting an optimal serum concentration of 40-60 nmol/L for the lowest cancer risk. Therefore, it is necessary to study several common aging-associated diseases such as osteoporosis, hypertension and diabetes known to be vitamin D-dependent before any recommendations of an optimal serum concentration of calcidiol are given.

Serum vitamin D and risk of pancreatic cancer in the prostate, lung, colorectal, and ovarian screening trial

Experimental evidence suggests that vitamin D has anticarcinogenic properties; however, a nested case-control study conducted in a population of male Finnish smokers found that higher 25-hydroxyvitamin D [25(OH)D], the best indicator of vitamin D status as determined by the sun and diet, was associated with a significant 3-fold increased risk for pancreatic cancer. We conducted a nested case-control study in the Prostate, Lung, Colorectal, and Ovarian Screening Trial cohort of men and women 55 to 74 years of age at baseline to test whether prediagnostic serum 25(OH)D concentrations were associated with pancreatic cancer risk. Between 1994 and 2006, 184 incident cases of pancreatic adenocarcinoma occurred (follow-up to 11.7 years). Two controls (n = 368) who were alive at the time the case was diagnosed were selected for each case and matched by age, race, sex, and calendar date of blood draw (to control for seasonal variation). We calculated odds ratios (OR) and 95% confidence intervals (95% CI) using conditional logistic regression, adjusting for smoking and body mass index. Vitamin D concentrations were not associated with pancreatic cancer overall (highest versus lowest quintile, >82.3 versus <45.9 nmol/L: OR, 1.45; 95% CI, 0.66-3.15; P trend = 0.49). However, positive associations were observed among subjects with low estimated annual residential solar UBV exposure, but not among those with moderate to high annual exposure (P interaction = 0.015). We did not confirm the previous strong positive association between 25(OH)D and pancreatic cancer; however, the increased risk among participants with low residential UVB exposure is similar.

Association between serum 25(OH)D and death from prostate cancer

Based on observations that for certain cancers, mortality varies according to sun exposure, vitamin D has been proposed to influence on disease progression. This study aims to investigate whether serum levels of 25(OH)D are associated with prognosis in patients with prostate cancer. In total, 160 patients with a serum sample in the JANUS serum bank were included. For 123 patients a pre-treatment serum sample was taken, whereas 37 of the patients had received hormone therapy prior to the blood collection. The serum level of 25(OH)D was classified as low (<50 nmol l(-1)), medium (50-80 nmol l(-1)) or high (>80 nmol l(-1)). A Cox proportional hazard regression model was used to assess the association between serum 25(OH)D and cancer mortality. During follow-up, 61 deaths occurred, of whom 52 died of prostate cancer. The median time of follow-up was 44.0 months (range, 1.2-154.6). Serum 25(OH)D at medium or high levels were significantly related to better prognosis (RR 0.33; 95% CI 0.14-0.77, RR 0.16; 95% CI 0.05-0.43) compared with the low level. Analysis restricted to patients receiving hormone therapy gave a stronger association. The serum level of 25(OH)D may be involved in disease progression and is a potential marker of prognosis in patients with prostate cancer.

Solar ultraviolet irradiance and cancer incidence and mortality

Evidence supporting the UVB/vitamin D/cancer theory continues to mount with little detraction, although there are some inconsistent results, such as some from Nordic countries, with respect to serum calcidiol levels. Also, studies designed and conducted before it was realized that dietary sources are largely inadequate to have a pronounced effect on cancer risk were largely unable to confirm a beneficial role for vitamin D in reducing the risk of cancer. The analysis of the economic burden of solar UVB irradiance and vitamin D deficiencies compared to excess solar UV irradiance for the United States yielded interesting findings. One was that the US economic burden due to vitamin D insufficiency from inadequate exposure to solar UVB irradiance, diet and supplements was estimated at $40 billion to $56 billion in 2004, whereas the economic burden for excess UV irradiance was estimated at $6 billion to $7 billion. These findings are probably still approximately correct, if not on the low side, with respect to vitamin D because of the additional benefits found recently, such as protection against infectious diseases.

Vitamin D and living in northern latitudes--an endemic risk area for vitamin D deficiency

OBJECTIVES

To review the current literature on the health effects of vitamin D, especially the effects on inhabitants living in the northern latitudes.

STUDY DESIGN

Literature review.

METHODS

The scientific literature concerning health effects of vitamin D was reviewed and the current dietary recommendations for inhabitants living in northern latitudes were discussed.

RESULTS

Vitamin D is a steroid-structured hormone produced in the skin upon exposure to UVB-radiation or obtained from certain food products (for example, liver). Its production is mediated by the vitamin D receptor, which belongs to the nuclear receptor family, and exerts its function as a transcription factor regulating several target genes. Active metabolites of vitamin D play an important role in calcium and phosphate homeostasis. Deficiency of vitamin D results in diminished bone mineralization and an increased risk of fractures. In addition, vitamin D is connected to a variety of other diseases that include different cancer types, muscular weakness, hypertension, autoimmune diseases, multiple sclerosis, type 1 diabetes, schizophrenia and depression.

CONCLUSIONS

Vitamin D plays a fundamental role in calcium and phosphate homeostasis. A deficiency of vitamin D has been attributed to several diseases. Since its production in the skin depends on exposure to UVB-radiation via the sunlight, the level of vitamin D is of crucial importance for the health of inhabitants who live in the Nordic latitudes where there is diminished exposure to sunlight during the winter season. Therefore, fortification or supplementation of vitamin D is necessary for most of the people living in the northern latitudes during the winter season to maintain adequate levels of circulating 25(OH)D3 to maintain optimal body function and prevent diseases.

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

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

VDR and SRD5A2 polymorphisms combine to increase risk for prostate cancer in both non-Hispanic White and Hispanic White men

PURPOSE

Vitamin D and dihydrotestosterone pathways interact to promote the growth of prostatic tissue. The nuclear vitamin D receptor (VDR) moderates the actions of vitamin D. 5alpha-Reductase type II (SRD5A2) codes for the enzyme that converts testosterone to dihydrotestosterone in the prostate. This study tested the interactions of VDR (CDX2, FokI) and SRD5A2 (V89L, A49T) polymorphisms, and their associations with prostate cancer.

EXPERIMENTAL DESIGN

This genetic association study included 932 non-Hispanic White (NHW) men and 414 Hispanic White (HW) men from South Texas. Cases had biopsy-confirmed cancer; controls had normal digital rectal exams and serum prostate-specific antigen levels of <2.5 ng/mL.

RESULTS

Using logistic regression analyses to test associations with prostate cancer, only the V89L polymorphism (VV genotype compared with LL/LV) in HW men was statistically significant [odds ratios (OR), 0.64; 95% confidence intervals (95% CI), 0.41-0.99]. The interaction terms for FokI and V89L in NHW men and CDX2 and V89L in HW men in the logistic model were significant (P = 0.02 and 0.03, respectively). When stratified by V89L genotype, the FokI polymorphism (TT/TC versus CC) was significantly associated with prostate cancer in NHW men with the V89L VV genotype (FokI OR, 1.53; 95% CI, 1.06-2.23). The CDX2 polymorphism (GG versus AG/AA) was significantly associated with prostate cancer only in HW men with the V89L VV genotype (CDX2 OR, 3.16; 95% CI, 1.39-7.19; interaction term P = 0.02).

CONCLUSION

Our results indicate that the SRD5A2 V89L VV genotype interacts with VDR FokI TT/CT genotypes in NHW men and VDR CDX2 GG genotypes in HW men to increase the risk for prostate cancer.

Vitamin D deficiency in children and its management: review of current knowledge and recommendations

Given the recent spate of reports of vitamin D deficiency, there is a need to reexamine our understanding of natural and other sources of vitamin D, as well as mechanisms whereby vitamin D synthesis and intake can be optimized. This state-of-the-art report from the Drug and Therapeutics Committee of the Lawson Wilkins Pediatric Endocrine Society was aimed to perform this task and also reviews recommendations for sun exposure and vitamin D intake and possible caveats associated with these recommendations.

Sun exposure and vitamin D sufficiency

Ultraviolet radiation is a carcinogen that also compromises skin appearance and function. Because the ultraviolet action spectra for DNA damage, skin cancer, and vitamin D(3) photosynthesis are identical and vitamin D is readily available from oral supplements, why has sun protection become controversial? First, the media and, apparently, some researchers are hungry for a new message. Second, the controversy is fueled by a powerful special interest group: the tanning industry. This industry does not target the frail elderly or inner-city ethnic minorities, groups for whom evidence of vitamin D(3) insufficiency is strongest, but rather fair-skinned teenagers and young adults, who are at highest risk of ultraviolet photodamage. Third, evolution does not keep pace with civilization. When nature gave humans the appealing capacity for cutaneous vitamin D(3) photosynthesis, life expectancy was <40 y; long-term photodamage was not a concern; and vitamin D(3) deficiency, with its resulting skeletal abnormalities (rickets), was likely to be fatal in early life. In the 21st century, life expectancy approaches 80 y in developed countries, vitamin D(3) is available at the corner store, and the lifetime risk of skin cancer is 1 in 3 among white Americans. Medical and regulatory groups should avoid poorly reasoned, sensationalistic recommendations regarding unprotected ultraviolet exposure. Instead, they should rigorously explore possible cause-and-effect relations between vitamin D(3) status and specific diseases while advocating the safest possible means of ensuring vitamin D(3) sufficiency.

Pesticides and prostate cancer: a review of epidemiologic studies with specific agricultural exposure information

Prostate cancer is the most commonly diagnosed cancer in US men, and the second most commonly diagnosed cancer among men worldwide. Although pesticides have been implicated in studies of prostate cancer among farmers, meta-analyses have found heterogeneity across studies, and a number of exposures and lifestyle factors may be unique to farmers. The purpose of this paper is to review the epidemiologic literature to evaluate the hypothesis that agricultural exposure to pesticides is causally associated with prostate cancer risk. We analyzed the eight cohort studies and five case-control studies that quantified and/or evaluated agricultural exposure to particular pesticide classes or chemicals. Despite sporadic positive findings, these studies did not show consistently increased risks to support a causal association between agricultural pesticide use and prostate cancer. Studies using an 'external' comparison group must be interpreted in the context of confounding by differences in prostate-specific antigen screening intensity. Furthermore, most studies did not adjust for potential confounders other than age and time period. It is clearly not possible to exonerate any particular pesticide as a putative cause of prostate cancer - to do so would require an inverse empirical association with an upper confidence limit below the null value. Existing evidence does not point to any pesticide as satisfying widely used guidelines for establishing causation: a strong, exposure-dependent and demonstrably unconfounded, unbiased association, documented in several studies.

Androgens and prevention of prostate cancer

PURPOSE OF REVIEW

This review provides a description of recent insights into the role of androgens in prostate cancer prevention.

RECENT FINDINGS

Many studies have elucidated a variety of molecular mechanisms involved in the initiation and progression of prostate cancer with many directly or indirectly related to the androgen signaling pathway. Both well known and novel agents for targeting the androgen pathway are under investigation, though very few are in clinical trials. After a review of recent papers describing these mechanisms, their results and implications were summarized.

SUMMARY

Finasteride remains the only agent proven to reduce the risk of prostate cancer, though there are currently two other ongoing phase III trials with vitamin E, selenium, and dutasteride. An enhanced understanding of complex interactions with the androgen pathways is leading to the exploration of additional promising approaches to mitigating the risk of prostate cancer.

Vitamin D and pancreatic cancer

Sun exposure has been associated with lower death rates for pancreatic cancer in ecological studies. Skin exposure to solar ultraviolet B radiation induces cutaneous production of precursors to 25-hydroxy (OH) vitamin D (D) and is considered the primary contributor to vitamin D status in most populations. Pancreatic islet and duct cells express 25-(OH) D(3)-1alpha-hydroxylase that generates the biologically active 1,25-dihydroxy(OH)(2) D form. Thus, 25(OH)D concentrations could affect pancreatic function and possibly pancreatic cancer etiology. Serum 25-(OH)D is the major circulating vitamin D metabolite and is considered the best indicator of vitamin D status as determined by the sun and diet. Although recent prospective epidemiologic studies of higher predicted vitamin D status score and vitamin D intake and pancreatic cancer risk suggest protective associations, a nested case-control study showed a significant 3-fold increased risk for pancreatic cancer with higher vitamin D status. Limitations of these studies include the former do not measure vitamin D status on pancreatic cancer cases and the later was conducted in a male smoker population. More research is needed, particularly examination of pre-diagnostic vitamin D status and risk of pancreatic cancer, prior to conclusions for vitamin D's potential role in the etiology of this highly fatal cancer.

Shedding light on vitamin D and integrative oncology

Studies show an important relationship between vitamin D and malignancies, both in prevention and treatment. The extraskeletal actions of vitamin D relevant to oncology include being proapoptotic, antimetastatic, antiangiogenic, antiinflammatory, prodifferentiating, and immunomodulating. Widespread and severe vitamin D deficiencies exist worldwide. Decreased sun exposure, caused by lifestyle changes, as well as fear of skin cancers, is the main cause of these deficiencies. Recommended daily oral intakes, as well as suggested blood levels, are below optimal levels suggested by studies. Improvement in vitamin D status, through lifestyle changes and supplementation, can be of profound benefit regarding the occurrence and mortality of malignancies.

Serum vitamin D concentration and prostate cancer risk: a nested case-control study

BACKGROUND

Epidemiological studies have yielded inconsistent associations between vitamin D status and prostate cancer risk, and few studies have evaluated whether the associations vary by disease aggressiveness. We investigated the association between vitamin D status, as determined by serum 25-hydroxyvitamin D [25(OH)D] level, and risk of prostate cancer in a case-control study nested within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.

METHODS

The study included 749 case patients with incident prostate cancer who were diagnosed 1-8 years after blood draw and 781 control subjects who were frequency matched by age at cohort entry, time since initial screening, and calendar year of cohort entry. All study participants were selected from the trial screening arm (which includes annual standardized prostate cancer screening). Conditional logistic regression was used to estimate adjusted odds ratios (ORs) with 95% confidence intervals (CIs) by quintile of season-standardized serum 25(OH)D concentration. Statistical tests were two-sided.

RESULTS

No statistically significant trend in overall prostate cancer risk was observed with increasing season-standardized serum 25(OH)D level. However, serum 25(OH)D concentrations greater than the lowest quintile (Q1) were associated with increased risk of aggressive (Gleason sum > or = 7 or clinical stage III or IV) disease (in a model adjusting for matching factors, study center, and history of diabetes, ORs for Q2 vs Q1 = 1.20, 95% CI = 0.80 to 1.81, for Q3 vs Q1 =1.96, 95% CI = 1.34 to 2.87, for Q4 vs Q1 = 1.61, 95% CI = 1.09 to 2.38, and for Q5 vs Q1 = 1.37, 95% CI = 0.92 to 2.05; P(trend) = .05). The rates of aggressive prostate cancer for increasing quintiles of serum 25(OH)D were 406, 479, 780, 633, and 544 per 100 000 person-years. In exploratory analyses, these associations with aggressive disease were consistent across subgroups defined by age, family history of prostate cancer, diabetes, body mass index, vigorous physical activity, calcium intake, study center, season of blood collection, and assay batch.

CONCLUSION

The findings of this large prospective study do not support the hypothesis that vitamin D is associated with decreased risk of prostate cancer; indeed, higher circulating 25(OH)D concentrations may be associated with increased risk of aggressive disease.

A novel tissue-slice culture model for non-malignant human prostate

A novel tissue culture system was established for modeling the non-neoplastic human prostate in vitro. Precision-cut prostate slices were cultivated in culture plates with a gas-permeable base in a novel serum-free mixture. Cultivated specimens was evaluated by an immunohistochemical analysis of cytokeratins 18 and 14, androgen receptor (AR), prostate specific antigen (PSA), prostate acid phosphatase (PAP), and the endothelial cell marker von Willebrand factor. Epithelial viability in the presence and absence of dihydrotestosterone (DHT) was also assessed. Satisfactory maintenance of glandular cytoarchitecture was observed in the presence of DHT with approximately half of the glands displaying a columnar or cuboidal phenotype and an intact layer of basal cells. In the absence of DHT, the corresponding percentage was significantly lower. The occurrence of involutive changes and epithelial cell death was significantly higher in the absence of DHT. Glandular and stromal cells maintained their capacity to express AR. PSA and PAP were expressed throughout the culture period, albeit at a lower level than in uncultured tissue. The viability of endothelial cells differed markedly between individual samples. During culture, the tissue slices became covered with epithelial cells originating from glands that were cut open during tissue slicing. This cell layer consisted of a stratified basal compartment overlaid by cells with a luminal phenotype. The present culture system provides a novel in vitro setting in which to study normal human prostate biology and pathobiology and may help to obviate problems related to the use of established cancer cell lines and animal models.

Vitamin D and cancer incidence in the Harvard cohorts

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

Role of hormonal and other factors in human prostate cancer

American men have a lifetime risk of about 18% for prostate cancer diagnosis. Large international variations in prostate cancer risks and increased risks among migrants from low- to high-risk countries indicate important roles for environmental factors. Major known risk factors include age, family history, and country/ethnicity. Type 2 diabetes appears to reduce risk, while high birth weight and adult height are linked to increased risk of aggressive prostate cancer. Limited evidence supports an association with a history of sexually transmitted infections. A previous meta-analysis of eight cohort studies indicated no associations with plasma androgen, estrogen, or sex hormone binding globulin (SHBG) levels. However, there were dose-response relationships with baseline plasma testosterone levels in two studies that adjusted for other serum hormones and obesity. Finasteride (a drug that blocks testosterone activation) reduced prostate cancer risk by 25%. Low-frequency genes linked to familial prostate cancer only explain a small fraction of all cases. Sporadic cases were linked to relatively common polymorphisms of genes involved in (1) androgen synthesis, activation, inactivation and excretion, (2) hormone and vitamin D receptors, (3) carcinogen metabolism, and (4) DNA repair. Epidemiologic evidence supports protective roles for dietary selenium, vitamin E, pulses, tomatoes/lycopene, and soy foods, and high plasma 1,25-dihydroxyvitamin D levels. There is inadequate evidence that vegetables, fruit, carotenoids, and vitamins A and C reduce risk and that animal fat, alpha-linoleic acid, meat, coffee, and tea increase risk. Two major cohort studies found dose-response relationships with dietary calcium intake. Total dietary energy intake may enhance risk. Limited evidence supports a protective role for physical activity and elevated risk for farmers and other men with occupational pesticide exposure, particularly to organochlorine compounds and phenoxy herbicides. There is inadequate evidence for a relationship with alcohol or smoking. Most known or suspected external risk factors may act through hormonal mechanisms, but our review found little supporting evidence, and substantial further research is needed.

Tanning and cutaneous malignancy

BACKGROUND

Exposure to ultraviolet radiation (UVR) results in a darkening of the skin known as tanning. Recently, it has been shown that tanning is a response to UVR-induced DNA damage and represents the skin's efforts to protect itself against further injury. Despite the link between UVR and cutaneous malignancy, people continue to pursue tanning from natural and artificial sources. This trend is reflected in the exponential rise in skin cancer incidence.

OBJECTIVE

The objective of this study was to review our current understanding of the factors controlling the tanning response and the relationship to cutaneous carcinogenesis, as well as the impact that the multibillion dollar tanning industry has had on the practice of dermatology.

MATERIALS AND METHODS

Extensive literature review was conducted in subjects related to tanning and the relationship to cutaneous malignancy.

RESULTS

Our knowledge of tanning and its effects on the skin has increased tremendously. It is clear that tanning contributes to the development of skin cancer. Despite this information, the incidence of skin cancer continues to increase exponentially.

CONCLUSIONS

Skin cancer poses a major public health concern and tanning remains the most modifiable risk factor in its etiology. Social, economic, and legislative issues have become tightly intertwined with the complex nature of human behavior in the continued pursuit of an activity that clearly has detrimental effects on one's health.

Comprehensive association analysis of the vitamin D pathway genes, VDR, CYP27B1, and CYP24A1, in prostate cancer

Genetic variation in vitamin D-related genes has not been investigated comprehensively and findings are equivocal. We studied the association between polymorphisms across the entire vitamin D receptor (VDR) gene and genes encoding for vitamin D activating enzyme 1-alpha-hydroxylase (CYP27B1) and deactivating enzyme 24-hyroxylase (CYP24A1) and prostate cancer risk among middle-aged men using a population-based case-control study design. DNA samples and survey data were obtained from incident cases (n = 630), 40 to 64 years old, identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry from 1993 to 1996 and from random controls (n = 565) of similar age without a history of prostate cancer. We selected and genotyped tag single-nucleotide polymorphisms to predict common variants across VDR (n = 22), CYP27B1 (n = 2), and CYP24A1 (n = 14). Haplotypes of VDR and CYP24A1 were not associated with prostate cancer risk. In the genotype analysis, homozygotes at two VDR loci (rs2107301 and rs2238135) were associated with a 2- to 2.5-fold higher risk of prostate cancer compared with the homozygote common allele [odds ratio, 2.47 (95% confidence interval, 1.52-4.00; P = 0.002) and 1.95 (95% confidence interval, 1.17-3.26; P = 0.007), respectively; P value corrected for multiple comparisons for VDR = 0.002]. We found no evidence that the two associated VDR single-nucleotide polymorphisms were modified by age at diagnosis, prostate cancer aggressiveness, first-degree family history of prostate cancer, or vitamin D intake. Genotypes of CYP27B1 and CYP24A1 were not associated with prostate cancer risk. Our findings suggest that polymorphisms in the VDR gene may be associated with prostate cancer risk and, therefore, that the vitamin D pathway might have an etiologic role in the development of prostate cancer.

Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers

Many viral infections reach clinical significance in winter, when it is cold, relative humidity is lowest and vitamin D production from solar ultraviolet-B irradiation is at its nadir. Several autoimmune diseases, such as multiple sclerosis, type 1 diabetes mellitus and asthma, are linked to viral infections. Vitamin D, through induction of cathelicidin, which effectively combats both bacterial and viral infections, may reduce the risk of several autoimmune diseases and cancers by reducing the development of viral infections. Some types of cancer are also linked to viral infections. The cancers with seemingly important risk from viral infections important in winter, based on correlations with increasing latitude in the United States, an index of wintertime solar ultraviolet-B dose and vitamin D, are bladder, prostate, testicular and thyroid cancer, Hodgkin's and non-Hodgkin's lymphoma, and, perhaps, gastric cancer. The evidence examined includes the role of viruses in the etiology of these diseases, the geographic and seasonal variation of these diseases, and the time of life when vitamin D is effective in reducing the risk of disease. In general, the evidence supports the hypothesis. However, further work is required to evaluate this hypothesis.

Serum 25(OH)-vitamin D concentration and risk of esophageal squamous dysplasia

BACKGROUND

Squamous dysplasia is the precursor lesion for esophageal squamous cell carcinoma, and nutritional factors play an important role in the etiology of this cancer. Previous studies using a variety of measures for vitamin D exposure have reached different conclusions about the association between vitamin D and the risk of developing esophageal cancer.

METHODS

We measured serum 25-hydroxyvitamin D [25(OH)D] concentrations in a cross-sectional analysis of 720 subjects from Linxian, China, a population at high risk for developing esophageal squamous cell carcinoma. All subjects underwent endoscopy and biopsy and were categorized by the presence or absence of histologic squamous dysplasia. We used crude and multivariate-adjusted generalized linear models to estimate the relative risks (RR) and 95% confidence intervals (95% CI) for the association between squamous dysplasia and sex-specific quartiles of serum 25(OH)D concentration.

RESULTS

Two-hundred and thirty of 720 subjects (32%) had squamous dysplasia. Subjects with dysplasia had significantly higher median serum 25(OH)D concentrations than subjects without dysplasia, 36.5 and 31.5 nmol/L, respectively (Wilcoxon two-sample test, P = 0.0004). In multivariate-adjusted models, subjects in the highest compared with the lowest quartiles were at a significantly increased risk of squamous dysplasia (RR, 1.86; 95% CI, 1.35-2.62). Increased risks were similar when examined in men and women separately: men (RR, 1.74; 95% CI, 1.08-2.93); women (RR, 1.96; 95% CI, 1.28-3.18).

CONCLUSIONS

Higher serum 25(OH)D concentrations were associated with significantly increased risk of squamous dysplasia. No obvious source of measured or unmeasured confounding explains this finding.

Serum 25(OH)-vitamin D concentration and risk of esophageal squamous dysplasia

BACKGROUND

Squamous dysplasia is the precursor lesion for esophageal squamous cell carcinoma, and nutritional factors play an important role in the etiology of this cancer. Previous studies using a variety of measures for vitamin D exposure have reached different conclusions about the association between vitamin D and the risk of developing esophageal cancer.

METHODS

We measured serum 25-hydroxyvitamin D [25(OH)D] concentrations in a cross-sectional analysis of 720 subjects from Linxian, China, a population at high risk for developing esophageal squamous cell carcinoma. All subjects underwent endoscopy and biopsy and were categorized by the presence or absence of histologic squamous dysplasia. We used crude and multivariate-adjusted generalized linear models to estimate the relative risks (RR) and 95% confidence intervals (95% CI) for the association between squamous dysplasia and sex-specific quartiles of serum 25(OH)D concentration.

RESULTS

Two-hundred and thirty of 720 subjects (32%) had squamous dysplasia. Subjects with dysplasia had significantly higher median serum 25(OH)D concentrations than subjects without dysplasia, 36.5 and 31.5 nmol/L, respectively (Wilcoxon two-sample test, P = 0.0004). In multivariate-adjusted models, subjects in the highest compared with the lowest quartiles were at a significantly increased risk of squamous dysplasia (RR, 1.86; 95% CI, 1.35-2.62). Increased risks were similar when examined in men and women separately: men (RR, 1.74; 95% CI, 1.08-2.93); women (RR, 1.96; 95% CI, 1.28-3.18).

CONCLUSIONS

Higher serum 25(OH)D concentrations were associated with significantly increased risk of squamous dysplasia. No obvious source of measured or unmeasured confounding explains this finding.

Associations of diet, supplement use, and ultraviolet B radiation exposure with vitamin D status in Swedish women during winter

BACKGROUND

Vitamin D is produced endogenously after sun exposure but can also be obtained from natural food sources, food fortification, and dietary supplements.

OBJECTIVE

We aimed to determine the vitamin D status of women (61-86 y old) living in central Sweden (latitude 60 degrees ) during winter and its relation with vitamin D intake and exposure to ultraviolet B radiation.

DESIGN

In a cross-sectional study, we assessed the vitamin D status (serum 25-hydroxyvitamin D [25(OH)D]) of 116 women by using an enzyme immunoassay. The women completed questionnaires covering food habits, use of dietary supplements, and sun-related behavior.

RESULTS

In a multiple linear regression model, the main determinants of serum 25(OH)D concentrations (x +/- SD: 69 +/- 23 mmol/L) were dietary vitamin D (6.0 +/- 1.8 mug/d), travel to a sunny location during winter within the previous 6 mo (26%), and the use of dietary supplements (16%). There was no association between serum 25(OH)D status during the winter and age, time spent outdoors, the use of sunscreen, or skin type. Serum 25(OH)D concentrations increased by 25.5 nmol/L with 2-3 servings (130 g/wk) fatty fish/wk, by 6.2 nmol/L with the daily intake of 300 g vitamin D-fortified reduced-fat dairy products, by 11.0 nmol/L with regular use of vitamin D supplements, and by 14.5 nmol/L with a sun vacation during winter. Among nonsupplement users without a wintertime sun vacation, 2-3 servings fatty fish/wk increased serum vitamin D concentrations by 45%.

CONCLUSION

Fatty fish, vitamin D-fortified reduced-fat dairy products, regular supplement use, and taking a sun vacation are important predictors for serum concentrations of 25(OH)D during winter at a latitude of 60 degrees .

Nordic biological specimen banks as basis for studies of cancer causes and control--more than 2 million sample donors, 25 million person years and 100,000 prospective cancers

The Nordic countries have a long tradition of large-scale biobanking and comprehensive, population-based health data registries linkable on unique personal identifiers, enabling follow-up studies spanning many decades. Joint Nordic biobank-based studies provide unique opportunities for longitudinal molecular epidemiological research. The purpose of the present paper is to describe the possibilities for such joint studies, by describing some of the major Nordic biobank cohorts with a standardised calculation of the cancer incidence in these cohorts. Altogether two million donors have since 1966 donated more than four million biological samples, stored at -20 degrees C to -135 degrees C, to 17 biobank cohorts in Finland, Iceland, Norway and Sweden. As a result of joint database handling principles, the accuracy of personal identifiers and completeness of follow-up for vital status in all participating biobanks was improved. Thereafter, the cancer incidence was determined using follow-up through the national cancer registries. Biobanks based on random samples of population typically showed slightly lower cancer incidence rates than the general population, presumably due to better participation rates among health-conscious subjects. On the other hand, biobanks including samples for viral screening or clinical testing showed 1.5 to 2.1 fold increased incidence of cancer. This excess was very high immediately after sampling, but for some cancer sites remained elevated for years after clinical sampling. So far, more than 100 000 malignant neoplasms have occurred after sample donation, and the annual increase of the cancer cases in these cohorts is about 10 000. The estimates on the population-representativity of the biobanks will assist in interpretation of generalizability of results of future studies based on these samples, and the systematic tabulations of numbers of cancer cases will serve in study power estimations. The present paper summarizes optimal study designs of biobank-based studies of cancer.

Regulation of 17beta-hydroxysteroid dehydrogenase type 2, type 4 and type 5 by calcitriol, LXR agonist and 5alpha-dihydrotestosterone in human prostate cancer cells

Vitamin D seems to be involved in the control of prostate cancer cell growth. 17beta-Hydroxysteroid dehydrogenases type 2, type 4 and type 5 are enzymes which regulate intracellular concentration of active sex steroid hormones, which in turn, regulate the development, growth, and function of the prostate and play a role in the development and progression of prostate cancer. Using quantitative real-time PCR we find that calcitriol up-regulates HSD17B type 2, type 4 and type 5 in human prostate cancer LNCaP and PC3 cells but not in stromal cells. LXR agonist, TO-901317, suppresses the expression of HSD17B2 mRNA and inhibits calcitriol induced HSD17B2 expression. TO-901317 up-regulates the expression of HSD17B5 but not that of HSD17B4. 5alpha-Dihydrotestosterone up-regulates the expression of HSD17B2 and HSD17B4 but it significantly inhibits HSD17B5 expression by 70%. Calcitriol has no effect on DHT mediated expression of the three genes. The regulation of HSD17B2, HSD17B4 and HSD17B5 by ligands of LXR and VDR as well as AR in prostate cancer cells suggests a complex interaction of these signaling systems in the prostate.

Prostate cancer survival is dependent on season of diagnosis

BACKGROUND

We have earlier found that the prognosis for several cancers is dependent on season of diagnosis. More recently, both prostate cancer incidence and mortality have been shown to increase with increasing latitude, which probably relates to photosynthesis of vitamin D.

METHODS

The 3 year survival of prostate cancer patients has been analyzed with the Cox regression method for two age groups at different latitudes in Norway.

RESULTS

Patients diagnosed during the summer and autumn had the best prognosis (Ralative risk (RR) death 0.8; 95% CI 0.75-0.85). Similar results were observed in three regions of the country that differ with respect to annual fluences of solar UV radiation, incidence rates of squamous cell carcinoma (SCC) and intake of fish. Furthermore, similar relationship between the season and survival was seen among patients </=65 years and >65 years old, although the younger group had a slightly larger advantage of summer and autumn diagnosis.

CONCLUSIONS

The seasonal effect on prognosis may be related to the seasonal variations of calcidiol (the marker of vitamin D status). The lack of latitude effect and the similarity of prognosis for different age groups may be related to higher consumption of vitamin D in food in the north region and to increase of such consumption with age.

Vitamin D receptor (VDR) gene polymorphisms and haplotypes, interactions with plasma 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, and prostate cancer risk

BACKGROUND

The vitamin D receptor (VDR) is required for actions of vitamin D. The binding of 1,25-dihydroxyvitamin D to the VDR on prostatic epithelial cells prompts the regulation of cancer-related genes.

METHODS

We conducted a nested case-control study in the Health Professionals Follow-up Study to investigate the role of the VDR Cdx2, Fok1, and Bsm1 gene polymorphisms and associated haplotypes and their interaction with plasma vitamin D metabolites in relation to prostate cancer (PC) risk.

RESULTS

No association was found between these SNPs or their associated haplotypes and all PC subtypes except that haplotype 2 (A-f-b) with Cdx2 A, Fok1 f, and Bsm1 b alleles and haplotype 3 (A-F-B) with Cdx2 A, Fok1 F and Bsm1 B alleles compared to the most common haplotype (A-F-b), were associated with reduced risk of aggressive PC (high stage or Gleason sum > or =7; P = 0.02), both with two alleles suspected of being low risk. Carriers of the variant Cdx2 A allele who were deficient in plasma 25-hydroxyvitamin D (< or =15 ng/ml) compared to non-carriers with normal 25-hydroxyvitamin D, had a lower risk of total and poorly differentiated PCs (Gleason sum > or =7) (P for interaction = 0.02 and 0.04, respectively). Plasma 1,25-dihydroxyvitamin D deficiency (< or =26 pg/ml) was associated with a threefold risk of poorly differentiated PC (P for interaction = 0.01) when comparing carriers of the Cdx2 A allele to non-carriers with normal 1,25-dihydroxyvitamin D.

CONCLUSION

In this population of men, none of the VDR polymorphisms studied was associated with susceptibility to PC.

Prospective study of serum 25(OH)-vitamin D concentration and risk of oesophageal and gastric cancers

We prospectively examined the relation between pretrial serum vitamin D status and risk of oesophageal and gastric cancers among subjects who developed cancer over 5.25 years of follow-up, including 545 oesophageal squamous cell carcinomas (ESCC), 353 gastric cardia adenocarcinomas, 81 gastric noncardia adenocarcinomas, and an age- and sex-stratified random sample of 1105 subjects. The distribution of serum 25(OH)D was calculated using the known sampling weights. For the cohort as a whole, the 25th, 50th, and 75th percentile concentrations of 25(OH)-vitamin D were 19.6, 31.9, and 48.7 nmol l(-1), respectively, and we found that higher serum 25(OH)D concentrations were associated with monotonically increasing risk of ESCC in men, but not in women. Comparing men in the fourth quartile of serum 25(OH)D concentrations to those in the first, we found a hazard ratio (HR) (95% confidence interval (CI)) of 1.77 (1.16-2.70), P trend=0.0033. The same comparison in women had a HR (95% CI) of 1.06 (0.71-1.59), P trend=0.70. We found no associations for gastric cardia or noncardia adenocarcinoma. Among subjects with low vitamin D status, higher serum 25(OH)D concentrations were associated with significantly increased risk of ESCC in men, but not in women. Further refinements of the analysis did not suggest any factors, which could explain this unexpected result.

Sun Exposure and Prostate Cancer Risk: Evidence for a Protective Effect of Early-Life Exposure

Mounting experimental and epidemiologic evidence supports the hypothesis that vitamin D reduces the risk of prostate cancer. Some evidence suggests that prostate cancer risk may be influenced by sun exposure early in life. We analyzed data from the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study to examine associations of prostate cancer risk with early-life and adult residential sun exposure and adult sun exposures that were assessed through self-report, physician report, and dermatologic examination. We used solar radiation in the state of birth as a measure of sun exposure in early life. Follow-up from 1971 to 1975 (baseline) to 1992 identified 161 prostate cancer cases (102 nonfatal and 59 fatal) among non-Hispanic white men for whom sun exposure data were available. Significant inverse associations were found for men born in a region of high solar radiation (relative risk, 0.49, 95% confidence interval, 0.27-0.90 for high versus low solar radiation), with a slightly greater reduction for fatal than for nonfatal prostate cancer. Frequent recreational sun exposure in adulthood was associated with a significantly reduced risk of fatal prostate cancer only (relative risk, 0.47; 95% confidence interval, 0.23-0.99). These findings suggest that, in addition to sun exposure in adulthood, sun exposure in early life protects against prostate cancer.

Vitamin D Status of Patients Admitted to a Hospital Rehabilitation Unit

OBJECTIVE

The primary objective was to determine the association between vitamin D status, baseline function, and short-term inpatient rehabilitation progress.

DESIGN

This was a prospective convenience sampling of 100 patients in a tertiary general hospital rehabilitation unit (RU). The cohort comprised men and women of mixed race with a variety of diagnoses (mean age 70 yrs). Patient histories and demographic information were obtained by patient interview and chart review. Serum 25-hydroxyvitamin D (25OHD) (nmol/L) was measured on or after the day of admission. The Functional Independence Measurement (FIM) instrument, a validated survey tool, was used to measure function at admission and discharge.

RESULTS

Eleven percent of the patients were overtly vitamin D deficient, with serum 25OHD concentrations <20 nmol/L. Ninety-four percent of the patients had serum 25OHD concentrations below the recommended minimum optimal concentration of 80 nmol/L. Using the Spearman rank correlation test, low serum 25OHD was weakly but significantly associated with low total FIM scores: r = 0.25 (P < 0.012) and r = 0.23 (P < 0.021) for admission and discharge total FIM score, respectively. Patients with serum 25OHD concentrations greater than the median value of 41.3 nmol/L had significantly higher FIM efficiency scores (discharge total FIM score - admission total FIM score/length of stay [LOS]) than the subgroup of patients below the median (2.0 +/- 1.1 vs. 1.6 +/- 0.9, respectively; P < or = 0.026). Serum 25OHD was not significantly correlated with FIM efficiency or the unadjusted change in total FIM score (discharge total FIM score - admission total FIM score), but it was significantly correlated with LOS (the lower the serum 25OHD concentration, the longer the LOS, and vice versa; r = -0.235, P < 0.018). Thus, the difference in FIM efficiency between patients with serum 25OHD above and below the median was the result of the significant inverse correlation between serum 25OHD and LOS; as a group, patients with serum 25OHD above the median had a 19% shorter LOS than the group with serum 25OHD below the median value (11.4 +/- 4.9 vs. 14.1 +/- 5.6 days, respectively; P = 0.005).

CONCLUSIONS

Most patients in a hospital RU had a suboptimal serum 25OHD concentration, reflecting what has previously been observed in hospitalized patients in general and also the population at large. Although no specific physical deficits or attributes could be directly attributed to low serum 25OHD, the baseline functional status of RU patients, LOS, and progress attributable to inpatient rehabilitation (FIM efficiency) were favorably affected by higher serum 25OHD concentrations.

Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: vitamin D as a possible explanation

BACKGROUND

Skin cancers are known to be associated with sun exposure, whereas sunlight through the production of vitamin D may protect against some cancers. The aim of this study was to assess whether patients with skin cancer have an altered risk of developing other cancers.

METHODS

The study cohort consisted of 416,134 cases of skin cancer and 3,776,501 cases of non-skin cancer as a first cancer extracted from 13 cancer registries. 10,886 melanoma and 35,620 non-melanoma skin cancer cases had second cancers. The observed numbers (O) of 46 types of second primary cancer after skin melanoma, basal cell carcinoma or non-basal cell carcinoma, and of skin cancers following non-skin cancers were compared to the expected numbers (E) derived from the age, sex and calendar period specific cancer incidence rates in each of the cancer registries (O/E=SIR, standardised incidence ratios). Rates from cancer registries classified to sunny countries (Australia, Singapore and Spain) and less sunny countries (Canada, Denmark, Finland, Iceland, Norway, Scotland, Slovenia and Sweden) were compared to each other.

RESULTS

SIR of all second solid primary cancers (except skin and lip) after skin melanoma were significantly lower for the sunny countries (SIR(S)=1.03; 95% CI 0.99-1.08) than in the less sunny countries (SIR(L)=1.14; 95%CI 1.11-1.17). The difference was more obvious after non-melanoma skin cancers: after basal cell carcinoma SIR(S)/SIR(L)=0.65 (95%CI=0.58-0.72); after non-basal cell carcinoma SIR(S)/SIR(L)=0.58 (95%CI=0.50-0.67). In sunny countries, the risk of second primary cancer after non-melanoma skin cancers was lower for most of the cancers except for lip, mouth and non-Hodgkin lymphoma.

CONCLUSIONS

Vitamin D production in the skin seems to decrease the risk of several solid cancers (especially stomach, colorectal, liver and gallbladder, pancreas, lung, female breast, prostate, bladder and kidney cancers). The apparently protective effect of sun exposure against second primary cancer is more pronounced after non-melanoma skin cancers than melanoma, which is consistent with earlier reports that non-melanoma skin cancers reflect cumulative sun exposure, whereas melanoma is more related to sunburn.

Interaction of factors related to the metabolic syndrome and vitamin D on risk of prostate cancer

BACKGROUND

Factors related to the metabolic syndrome and low levels of vitamin D have been implicated as risk factors for prostate cancer. Insofar, no studies have assessed their joint effects on prostate cancer risk.

METHODS

We studied (a) the associations of vitamin D with the metabolic syndrome factors body mass index, systolic and diastolic blood pressure, and high-density lipoprotein cholesterol (HDL-C) and (b) the prostate cancer risk associated with these factors and especially their joint effects with vitamin D on risk of prostate cancer. We did a longitudinal nested case-control study on 132 prostate cancer cases and 456 matched controls from a cohort of 18,939 Finnish middle-aged men from the Helsinki Heart Study. The odds ratios (OR) of prostate cancer were assessed via conditional logistic regression analysis.

RESULTS

Apart from HDL-C, there was no linear association between the metabolic syndrome factors and vitamin D levels. In univariate analysis, men in the highest quartiles of body mass index (>28 kg/m(2)) and systolic blood pressure (>150 mmHg) showed a modest increase in risks of prostate cancer, with ORs of 1.37 (P = 0.16) and 1.53 (P = 0.05) when compared with the three lower quartiles, but low HDL-C entailed no prostate cancer risk. However, with all three factors present, the OR was 3.36 (P = 0.02), and jointly with low vitamin D (<or=40 nmol/L), the OR was 8.03 (P = 0.005) compared with those with no metabolic syndrome factors and intermediate levels of vitamin D. There was an interaction between vitamin D and the metabolic syndrome factors so that a clustering of these factors entailed high risk of prostate cancer but only if vitamin D level was low (<or=40 nmol/L). If it was at intermediate levels, the metabolic syndrome factors entailed no prostate cancer risk.

CONCLUSIONS

We conclude that the prostate cancer risk associated with factors related to the metabolic syndrome is strongly conditioned by levels of vitamin D.

Calcium intake and vitamin D metabolism and action, in healthy conditions and in prostate cancer

An association between Ca intake and the risk of prostate cancer has been reported in some but not all epidemiological studies. Assuming that a pathophysiological relationship would underlie this association, a favoured hypothesis proposes that relatively high Ca consumption could promote prostate cancer by reducing the production of 1,25-dihydroxyvitamin D (1,25(OH)2D; calcitriol), the hormonal form of vitamin D. The present review analyses the plausibility of this hypothesis by considering the quantitative relationships linking Ca intake to 1,25(OH)2D production and action in healthy conditions and in prostate cancer. Changes in the plasma level of 1,25(OH)2D in response to Ca intake are of very small magnitude as compared with the variations required to influence the proliferation and differentiation of prostate cancer cells. In most studies, 1,25(OH)2D plasma level was not found to be reduced in patients with prostate cancer. The possibility that the level of 1,25(OH)2D in prostate cells is decreased with a high-Ca diet has not been documented. Furthermore, a recent randomised placebo-controlled trial did not indicate that Ca supplementation increases the relative risk of prostate cancer in men. In conclusion, the existence of a pathophysiological link between relatively high Ca intake and consequent low production and circulation level of 1,25(OH)2D that might promote the development of prostate cancer in men remains so far an hypothesis, the plausibility of which is not supported by the analysis of available clinical data.

B, J. W, M T. Dietary calcium does not affect prostate tumor progression in LPB-Tag transgenic mice

High dietary calcium has been shown in epidemiological studies to be a risk factor for prostate cancer, and it has been postulated that this effect is secondary to calcium induced modulation of the vitamin D axis. In this study, we used LPB-Tag transgenic mice on the CD1 background to examine the impact of dietary calcium on prostate tumor progression. CD1-LPB-Tag mice predictably develop autochthonous, hormone-responsive prostate tumors by 3 months of age. Age matched transgenic and non-transgenic littermates were weaned onto high (2%) or low (0.2%) calcium diets and mice were sacrificed at 5, 7, and 9 weeks of age. The entire urogenital complex was excised, weighed, and processed for histology. There was no significant effect of dietary calcium on tumor weight or on the time course of tumor progression, as monitored using a modified Gleason grade (MGS). Serum calcium was maintained in the normal range in mice on the low and high calcium diet throughout the study. Circulating 1,25(OH)(2)D(3) was elevated by low dietary calcium in 5-week-old mice, but not in older animals. In summary, neither development nor progression of prostate tumors in LPB-Tag mice was accelerated by high dietary calcium.

A prospective study of plasma vitamin D metabolites, vitamin D receptor polymorphisms, and prostate cancer

BACKGROUND

Vitamin D insufficiency is a common public health problem nationwide. Circulating 25-hydroxyvitamin D3 (25[OH]D), the most commonly used index of vitamin D status, is converted to the active hormone 1,25 dihydroxyvitamin D3 (1,25[OH]2D), which, operating through the vitamin D receptor (VDR), inhibits in vitro cell proliferation, induces differentiation and apoptosis, and may protect against prostate cancer. Despite intriguing results from laboratory studies, previous epidemiological studies showed inconsistent associations of circulating levels of 25(OH)D, 1,25(OH)2D, and several VDR polymorphisms with prostate cancer risk. Few studies have explored the joint association of circulating vitamin D levels with VDR polymorphisms.

METHODS AND FINDINGS

During 18 y of follow-up of 14,916 men initially free of diagnosed cancer, we identified 1,066 men with incident prostate cancer (including 496 with aggressive disease, defined as stage C or D, Gleason 7-10, metastatic, and fatal prostate cancer) and 1,618 cancer-free, age- and smoking-matched control participants in the Physicians' Health Study. We examined the associations of prediagnostic plasma levels of 25(OH)D and 1,25(OH)2D, individually and jointly, with total and aggressive disease, and explored whether relations between vitamin D metabolites and prostate cancer were modified by the functional VDR FokI polymorphism, using conditional logistic regression. Among these US physicians, the median plasma 25(OH)D levels were 25 ng/ml in the blood samples collected during the winter or spring and 32 ng/ml in samples collected during the summer or fall. Nearly 13% (summer/fall) to 36% (winter/spring) of the control participants were deficient in 25(OH)D (<20 ng/ml) and 51% (summer/fall) and 77% (winter/spring) had insufficient plasma 25(OH)D levels (<32 ng/ml). Plasma levels of 1,25(OH)2D did not vary by season. Men whose levels for both 25(OH)D and 1,25(OH)2D were below (versus above) the median had a significantly increased risk of aggressive prostate cancer (odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.2-3.4), although the interaction between the two vitamin D metabolites was not statistically significant (pinteraction = 0.23). We observed a significant interaction between circulating 25(OH)D levels and the VDR FokI genotype (pinteraction < 0.05). Compared with those with plasma 25(OH)D levels above the median and with the FokI FF or Ff genotype, men who had low 25(OH)D levels and the less functional FokI ff genotype had increased risks of total (OR = 1.9, 95% CI 1.1-3.3) and aggressive prostate cancer (OR = 2.5, 95% CI 1.1-5.8). Among men with plasma 25(OH)D levels above the median, the ff genotype was no longer associated with risk. Conversely, among men with the ff genotype, high plasma 25(OH)D level (above versus below the median) was related to significant 60% approximately 70% lower risks of total and aggressive prostate cancer.

CONCLUSIONS

Our data suggest that a large proportion of the US men had suboptimal vitamin D status (especially during the winter/spring season), and both 25(OH)D and 1,25(OH)2D may play an important role in preventing prostate cancer progression. Moreover, vitamin D status, measured by 25(OH)D in plasma, interacts with the VDR FokI polymorphism and modifies prostate cancer risk. Men with the less functional FokI ff genotype (14% in the European-descent population of this cohort) are more susceptible to this cancer in the presence of low 25(OH)D status.

Sun protection and Vitamin D: three dimensions of obfuscation

Ultraviolet (UV) radiation is a proven carcinogen, responsible for more than half of all human malignancies. It also compromises skin appearance and function. Since the UV action spectra for DNA damage, skin cancer and Vitamin D(3) (vit D) photosynthesis are identical and vit D is readily available from oral supplements, why has sun protection become controversial, now that some data suggest conventionally "sufficient" levels of vit D may be less than optimal for at least some population groups? First, the media and apparently some researchers are hungry for a new message. Nevertheless, after 50 years, UV exposure is still a major avoidable health hazard. Second, the controversy is fueled by a powerful special interest group: the indoor tanning industry. They target not the frail elderly or inner-city ethnic minorities, groups for whom evidence of vit D insufficiency is strongest, but rather fair-skinned teenagers and young adults, those at highest risk of UV photodamage. Third, evolution does not keep pace with civilization. When nature gave man the appealing capacity for vit D photosynthesis, the expected lifespan was far less than 40 years. Long-term photodamage was not a concern, and vit D was not available at the corner store. The medical community should avoid sensationalism and instead rigorously explore possible cause-and-effect relationships between vit D status and specific diseases while advocating the safest possible means of assuring vit D sufficiency.

UV, latitude, and spatial trends in prostate cancer mortality: all sunlight is not the same (United States)

OBJECTIVE

We showed previously that Caucasian mortality rates from prostate cancer for 1970-1979 are significantly inversely correlated with ultraviolet (UV) radiation. We now present the analysis of prostate cancer mortality data over a 45-year period (1950-1994) in order to examine the persistence of this pattern. Furthermore, because vitamin D synthesis does not occur during winter months at latitudes higher than 40 degrees N, we examined this relationship above and below 40 degrees N latitude.

METHODS

We used trend surface and linear regression analyses to characterize the relationship between prostate cancer mortality and UV radiation for U.S. counties at northern and southern latitudes.

RESULTS

For U.S. Caucasians, prostate cancer mortality rates at the county and SEA levels followed a significant north-south spatial trend that is the inverse of UV radiation. We found significant inverse correlations between UV radiation and prostate cancer mortality at all time points over this 45-year period. These correlations were significantly more pronounced at locations north of 40 degrees N latitude.

CONCLUSIONS

Our analyses confirm and extend our findings that the geographic distribution of prostate cancer mortality is the inverse of that of UV radiation. This effect is strongest in counties north of 40 degrees N latitude, where vitamin D synthesis is limited to non-winter months. These findings add additional support for the hypothesis that vitamin D insufficiency increases risk for prostate cancer.

A comparison of sunlight exposure in men with prostate cancer and basal cell carcinoma

Ultraviolet radiation exposure increases basal cell carcinoma (BCC) risk, but may be protective against prostate cancer. We attempted to identify exposure patterns that confer reduced prostate cancer risk without increasing that of BCC. We used a questionnaire to assess exposure in 528 prostate cancer patients and 442 men with basal cell carcinoma, using 365 benign prostatic hypertrophy patients as controls. Skin type 1 (odds ratio (OR)=0.47, 95% CI=0.26–0.86), childhood sunburning (OR=0.38, 95% CI=0.26–0.57), occasional/frequent sunbathing (OR=0.21, 95% CI=0.14–0.31), lifetime weekday (OR=0.85, 95% CI=0.80–0.91) and weekend exposure (OR=0.79, 95% CI=0.73–0.86) were associated with reduced prostate cancer risk. Skin type 1 (OR=4.00, 95% CI=2.16–7.41), childhood sunburning (OR=1.91, 95% CI=1.36–2.68), regular foreign holidays (OR=6.91, 95% CI=5.00-9.55) and weekend (OR=1.17, 95% CI=1.08–1.27) but not weekday exposure were linked with increased BCC risk. Combinations of one or two parameters were associated with a progressive decrease in the ORs for prostate cancer risk (OR=0.54–0.25) with correspondingly increased BCC risk (OR=1.60–2.54). Our data do not define exposure patterns that reduce prostate cancer risk without increasing BCC risk.

The effects on human health from stratospheric ozone depletion and its interactions with climate change

Ozone depletion leads to an increase in the ultraviolet-B (UV-B) component (280-315 nm) of solar ultraviolet radiation (UVR) reaching the surface of the Earth with important consequences for human health. Solar UVR has many harmful and some beneficial effects on individuals and, in this review, information mainly published since the previous report in 2003 (F. R. de Gruijl, J. Longstreth, M. Norval, A. P. Cullen, H. Slaper, M. L. Kripke, Y. Takizawa and J. C. van der Leun, Photochem. Photobiol. Sci., 2003, 2, pp. 16-28) is discussed. The eye is exposed directly to sunlight and this can result in acute or long-term damage. Studying how UV-B interacts with the surface and internal structures of the eye has led to a further understanding of the location and pathogenesis of a number of ocular diseases, including pterygium and cataract. The skin is also exposed directly to solar UVR, and the development of skin cancer is the main adverse health outcome of excessive UVR exposure. Skin cancer is the most common form of malignancy amongst fair-skinned people, and its incidence has increased markedly in recent decades. Projections consistently indicate a further doubling in the next ten years. It is recognised that genetic factors in addition to those controlling pigment variation can modulate the response of an individual to UVR. Several of the genetic factors affecting susceptibility to the development of squamous cell carcinoma, basal cell carcinoma and melanoma have been identified. Exposure to solar UVR down-regulates immune responses, in the skin and systemically, by a combination of mechanisms including the generation of particularly potent subsets of T regulatory cells. Such immunosuppression is known to be a crucial factor in the generation of skin cancers. Apart from a detrimental effect on infections caused by some members of the herpesvirus and papillomavirus families, the impact of UV-induced immunosuppression on other microbial diseases and vaccination efficacy is not clear. One important beneficial effect of solar UV-B is its contribution to the cutaneous synthesis of vitamin D, recognised to be a crucial hormone for bone health and for other aspects of general health. There is accumulating evidence that UVR exposure, either directly or via stimulation of vitamin D production, has protective effects on the development of some autoimmune diseases, including multiple sclerosis and type 1 diabetes. Adequate vitamin D may also be protective for the development of several internal cancers and infections. Difficulties associated with balancing the positive effects of vitamin D with the negative effects of too much exposure to solar UV-B are considered. Various strategies that can be adopted by the individual to protect against excessive exposure of the eye or the skin to sunlight are suggested. Finally, possible interactions between ozone depletion and climate warming are outlined briefly, as well as how these might influence human behaviour with regard to sun exposure.

Vitamin D and cancer

1,25-dihydroxy Vitamin D [1,25-(OH)(2)D] exerts its effects via the vitamin D receptor (VDR) that belongs to the steroid/thyroid hormone receptor superfamily leading to gene regulation which results in various biological responses. Within the last two decades, the receptor has been shown to be present not only in classical target tissues such as bone, kidney and intestine but also in many other non-classical tissues. Besides the almost universal presence of VDRs, some cell types (e.g. keratinocytes, monocytes, bone, placenta) are capable of metabolizing 25-hydroxyvitamin D to 1,25(OH)(2)D by the enzyme 1alpha-hydroxylase (CYP27B1). The combined presence of 25(OH)D-1alpha-hydroxylase as well as the specific receptor in several tissues introduced the idea of a paracrine role for 1,25(OH)(2)D. Moreover, it has been demonstrated that 1,25(OH)(2)D can induce differentiation and inhibit proliferation of a wide variety of cell types. The molecular mechanisms behind this antiproliferative action is thoroughly explored but the whole picture is still difficult to understand. Important cell cycle regulators are involved such as cyclins, cyclin dependent kinases and their corresponding inhibitors as well as E2F transcription factors and accompanying pocket proteins. However the precise hierarchical structure of this wide diversity of actions of 1,25(OH)(2)D on genes influencing cell cycle progression is not firmly established nor do we understand which pathways are essential and which redundant. The antiproliferative action makes 1,25-(OH)(2)D and its analogs a possible therapeutic tool to treat hyperproliferative disorders, among which different types of cancer. This review focuses on the effects of 1,25(OH)(2)D and its analogs on cell proliferation, the results in in vivo experiments in Vitamin D deficient or resistant animals to cancer and the current epidemiological and intervention studies linking Vitamin D status or treatment and human cancer.

Rise in Prostate-Specific Antigen in Men with Untreated Low-Grade Prostate Cancer Is Slower During Spring-Summer

To test the hypothesis that the rate of rise in prostate-specific antigen (PSA) is slower during the spring-summer than during the rest of the year, we used PSA data from a prospective single-arm cohort study of men who had been followed to characterize a watchful observation protocol with selective delayed intervention for clinically localized, low-to-intermediate grade prostate adenocarcinoma. The rate of PSA increase was calculated as the visit-to-visit slope of log (PSA) against time, from 1 calendar-quarter visit to the next. The nonparametric Friedman test confirmed differences in rate of PSA rise among the calendar quarters (P = 0.041). Post hoc analysis showed the rate of PSA increase during Q2 was significantly slower than in each one of the other calendar quarters (Q1 versus Q2, P = 0.025; Q3 versus Q2, P = 0.002; Q4 versus Q2, P = 0.013), with no differences among quarters Q1, Q3, and Q4. These results are consistent with the vitamin D hypothesis that the higher 25-hydroxyvitamin D levels associated with spring and summer have a desirable effect on prostate biology. The therapeutic implication is that vitamin D supplementation in the range of 2000 IU/d, a dose comparable to the effect of summer, can benefit men monitored for rising PSA.

Epidemiology of disease risks in relation to vitamin D insufficiency

Vitamin D from ultraviolet-B (UVB) irradiance, food, and supplements is receiving increased attention lately for its role in maintaining optimal health. Although the calcemic effects of vitamin D have been known for about a century, the non-calcemic effects have been studied intently only during the past two-three decades. The strongest links to the beneficial roles of UVB and vitamin D to date are for bone and muscle conditions and diseases. There is also a preponderance of evidence from a variety of studies that vitamin D reduces the risk of colon cancer, with 1000 IU/day of vitamin D or serum 25-hydroxyvitamin D levels >33 ng/mL (82 nmol/L) associated with a 50% lower incidence of colorectal cancer. There is also reasonable evidence that vitamin D reduces the risk of breast, lung, ovarian, and prostate cancer and non-Hodgkin's lymphoma. There is weaker, primarily ecologic, evidence for the role of vitamin D in reducing the risk of an additional dozen types of cancer. There is reasonably strong ecologic and case-control evidence that vitamin D reduces the risk of autoimmune diseases including such as multiple sclerosis and type 1 diabetes mellitus, and weaker evidence for rheumatoid arthritis, osteoarthritis, type 2 diabetes mellitus, hypertension and stroke. It is noted that mechanisms whereby vitamin D exerts its effect are generally well understood for the various conditions and diseases discussed here.

Does sunlight have a beneficial influence on certain cancers?

Apperly [1941. The relation of solar radiation to cancer mortality in North America. Cancer Research 1, 191-195] first proposed that increased mortality from cancer in the north than in the south of the USA might be due to the south to north decrease in ambient solar radiation. This inverse association between ambient solar radiation and cancer mortality has been subsequently reported for cancers of the colon, breast, ovary and prostate. While the evidence that sunlight might be related to lower incidence or more favourable outcomes from cancer came initially from ecological studies, case-control and cohort studies have now shown a similar association of sun exposure with risks of colon, breast and prostate cancers in individuals, and other studies in individuals have found that serum and dietary vitamin D levels are associated with reduced risks of colorectal cancer and, less certainly, prostate cancer. Studies in individuals have recently also suggested an effect of sun exposure to reduce risk of non-Hodgkin lymphoma and to increase survival after a diagnosis of melanoma. Data on variation in survival from cancer by season of diagnosis suggest that sun exposure may also improve outcome from cancers of the breast, colon and prostate and Hodgkin lymphoma.