Sun exposure may increase risk of prostate cancer in the high UV environment of New South Wales, Australia: a case-control study

Cutaneous melanoma, prostate-specific antigen testing and the subsequent risk of prostate cancer diagnosis: a prospective analysis of the 45 and Up Study

BACKGROUND

The association between cutaneous melanoma and subsequent risk of prostate cancer (PC) was examined in a large population-based cohort study.

METHODS

Male participants in the Sax Institute's 45 and Up Study (Australia) were recruited between 2006 and 2009. Questionnaire data and linked administrative health data from the Centre for Health Record Linkage and Services Australia identified melanomas diagnosed between 1/1/1994 and 12 months before Study recruitment (i.e., between 2005 and 2008), incident PCs, primary healthcare utilisation and prostate-specific antigen (PSA) tests. Men were excluded from the current analyses if they had a recorded PC or other cancer diagnosis other than melanoma and non-melanoma skin cancer prior to recruitment. Multivariable Cox regression was used to estimate hazard ratios (HRs) adjusting for PSA-testing frequency before PC diagnosis.

RESULTS

Of 96,548 eligible men, 1899 were diagnosed with melanoma during the melanoma diagnosis period and 3677 incident PC diagnosed during follow-up (latest date 31/12/2013). Men with melanoma diagnosis had increased risk of a subsequent PC diagnoses (vs. no melanoma; fully adjusted HR = 1.32; 95% CI: 1.09-1.60). There was weak evidence of higher risks of a subsequent PC diagnosis for men diagnosed with more than one melanoma compared to men diagnosed with only one melanoma (p = 0.077), and if first melanoma diagnosis was 10 to 15 years before Study recruitment (fully adjusted HR = 2.05; 95% CI [1.35, 3.12]).

CONCLUSION

Melanoma diagnosis was associated with increased risk of subsequent PC diagnosis, after adjusting for PSA testing and primary healthcare utilisation. While our ability to adjust for PC screening reduced risk of detection bias, we acknowledge that residual confounding from increased medical surveillance after melanoma diagnoses cannot be entirely ruled out.

Occupational exposure to solar ultraviolet B radiation and risk of prostate cancer in Danish men

OBJECTIVES

Former epidemiological studies have indicated that solar ultraviolet B radiation (UV) may reduce the risk of prostate cancer, however, the evidence is inconclusive. To contribute with evidence, the present study aimed to evaluate the association between occupational UV exposure and prostate cancer in Danish men.

METHODS

A total of 12,268 men diagnosed with primary prostate cancer before age 70 were identified via the Danish Cancer Registry. The Danish Civil Registration System was used to randomly select five male controls matched on year of birth, alive and free of prostate cancer at the time of diagnosis of the index case. Full individual-level employment history was retrieved from the Danish Supplementary Pension Fund Register and linked to a job exposure matrix to assess occupational UV exposure. Conditional logistic regression was used to estimate odds ratios (ORs) with corresponding 95 % confidence intervals.

RESULTS

We observed an inverse association between ever exposure to occupational UV and prostate cancer (OR=0.93, 95 % CI: 0.89-0.97). Longer duration of exposure (≥20 years: OR=0.90, 95 % CI: 0.84-0.96) and highest cumulative exposure (OR=0.90, 95 % CI: 0.84-0.96) were both inversely associated with disease risk.

CONCLUSIONS

The present study indicates a modest protective effect from occupational UV exposure on the risk of prostate cancer. This finding needs further attention in future large-scale studies.

Association between sunlight exposure and risk of prostate cancer: a systematic review and meta-analysis

BACKGROUND

The prevalence of prostate cancer (PC) is increasing worldwide. An association between sunlight exposure and PC risk has been described by a previously published meta-analysis, although the level of statistical significance was not reached. We have, therefore, performed an updated systematic review and meta-analysis to further elucidate this potential connection.

METHODS

To identify relevant articles, we conducted an in-depth search of 4 electronic databases (PubMed, Embase, the Web of Science and Scopus) for manuscripts published prior to March 2021. A random-effects model was used to compute a meta-estimate of the effects of sunlight exposure on risk of PC.

RESULTS

Of the 5680 articles that were initially identified in our search, 12 observational epidemiological studies encompassing 29 282 cases of PC were selected for inclusion in the qualitative systematic review. Of these, two case-control studies were excluded from the meta-analysis. Comparing highest-to-lowest exposure, personal sunlight exposure was significantly associated with a decreased risk of PC [odds ratio (OR) = 0.67, 95% CI: 0.57-0.78] in a random-effects meta-analysis; however, high heterogeneity was present (I2 = 85.9%). Comparing moderate-to-lowest exposure, there was a non-significant relationship between personal sunlight exposure and the risk of PC (OR = 0.87, 95% CI: 0.68-1.10; I2 = 74.0%).

CONCLUSIONS

Our findings indicate that exposure to sunlight may protect against PC. The limitations of our research are occurrence of publication bias and a substantial heterogeneity due to a diversity of criteria for measuring sunlight exposure.

Role of vitamin D3 in selected malignant neoplasms

Vitamin D₃ is a fat-soluble essential nutrient that affects multiple biologic functions in the organism through calcitriol and the vitamin D₃ receptor. This review article focuses on the results of studies on the relationship between the level of vitamin D₃ and cancer incidence or mortality, but also on the anticancer properties of vitamin D₃ that support its significant role in the prevention, clinical course, and overall survival rates of selected cancers (colorectal, prostate, breast, ovarian, endometrial, bladder, and malignant melanoma). The mechanisms of vitamin D₃ action involve, among others, polymorphism of vitamin D₃ receptor, cell cycle, caspases, and cancer stem cells. The level of vitamin D₃ has been also demonstrated to serve as a biomarker in some cancers, and high levels of vitamin D₃ can be conducive to successful cancer therapy.

Second primary malignancies in patients with non-melanoma skin cancer: Results from a cancer registry-based study in Emilia Romagna, north-east Italy

BACKGROUND

previous research on the risk of subsequent, primary non-cutaneous malignancies among patients with non-melanoma skin cancers (NMSCs) led to conflicting results. We aimed to investigate a possible link between NMSC and second primary malignancies by using the population-based data available in cancer registries.

METHODS

this observational study retrospectively assessed the risk of occurrence of both synchronous and methachronous second primary tumours in a cohort of cancer patients whose first diagnosis was NMSC. The cohort came from the network of general cancer registries of the Emilia-Romagna Region, northeast Italy, in the period between 1978 and 2012, and was compared with the general population living in the same area. Two main indexes were used: i) Standardized Incidence Ratio (SIR), calculated as the ratio between the observed and the expected number of second cancers and ii) Excess Absolute Risk (EAR), expressing the absolute excess or deficit of second cancer incidence.

RESULTS

in the period analysed (1978-2012, 72,503,157 person/years, PYs), 89,912 primary NMSC were found in 76,414 patients. Among them, 14,195 developed a second primary cancer in the subsequent 501,763 follow-up PYs. NMSC patients showed an overall SIR of 1.22 (CI 95% 1.20-1,24) and an EAR of 5.11 cases/1000 PYs (CI 95% 4.48-5.74).

CONCLUSIONS

the study results showed that NMSC patients had an increase in relative risk and, at least for some tumours, in absolute risk of developing a second cancer when compared with the general population. Genetic, environmental and personal risk factors may influence this finding.

Phytochemicals in Prostate Cancer: From Bioactive Molecules to Upcoming Therapeutic Agents

Prostate cancer is a heterogeneous disease, the second deadliest malignancy in men and the most commonly diagnosed cancer among men. Traditional plants have been applied to handle various diseases and to develop new drugs. Medicinal plants are potential sources of natural bioactive compounds that include alkaloids, phenolic compounds, terpenes, and steroids. Many of these naturally-occurring bioactive constituents possess promising chemopreventive properties. In this sense, the aim of the present review is to provide a detailed overview of the role of plant-derived phytochemicals in prostate cancers, including the contribution of plant extracts and its corresponding isolated compounds.

Melanoma patients with additional primary cancers: a single-center retrospective analysis

Background: Recent progress in the diagnosis and treatment of primary and metastatic cutaneous melanoma (CM) has led to a significant increase in the patients` expectancy of life. The development of additional primary tumors (APT) other than CM represents an important survival issue. Results: Of a total of 1764 CM patients, 80 (4.5%) patients developed APT. For tumors diagnosed after CM, there was a 2.7 fold excess risk for APT compared to the swiss german population. A significantly increased risk was noted for female breast (SIR, 2.46), male larynx (SIR, 76.92), male multiple myeloma (SIR, 11.2), male oesophagus (SIR, 10.8) and thyroid on males (SIR, 58.8) and females (SIR, 38.1). All thyroid cancer cases had a common papillary histological subtype and a high rate of BRAFV600E mutation. Melanoma was the primary cause of death in the vast majority of patients. Methods: We used the cancer registry from the Comprehensive Cancer Center Zurich (CCCZ) and retrospectively analyzed patients with CM and APT between 2008 and 2018. We calculated the risk of APT compared to the swiss german population using the standardized incidence ratio (SIR). Conclusions: Patients with CM have an increased risk for hematologic and solid APT. Long-term follow-up is indicated.

PAX3 is a biomarker and prognostic factor in melanoma: Database mining

Paired box 3 (PAX3) is a transcription factor and critical regulator of pigment cell development during embryonic development. However, while there have been several studies on PAX3, its expression patterns and precise role remain to be clarified. The present study is an in-depth computational study of tumor-associated gene information, with specific emphasis on the expression of PAX3 in melanoma, using Oncomine along with an investigation of corresponding expression profiles in an array of cancer cell lines through Cancer Cell Line Encyclopedia analysis. Based on Kaplan-Meier analysis, the prognostic value of high PAX3 expression in tissues from patients with melanoma compared with normal tissues was assessed. PAX3 was more highly expressed in male patients with melanoma compared with female patients with melanoma. Using Oncomine and Coexpedia analysis, it was demonstrated that PAX3 expression was clearly associated with SRY-box 10 expression. The survival analysis results revealed that high PAX3 mRNA expression was associated with worse survival rates in patients with melanoma. These results suggested that PAX3 may be a biomarker and essential prognostic factor for melanoma, and provided an important theoretical basis for the development of melanoma treatments.

Does sunlight protect us from cancer?

The Ultraviolet (UV) radiation contained in sunlight is a powerful mutagen and immune suppressant which partly explains why exposure to solar UV is the biggest risk factor for the development of cutaneous tumours. Evidence is building that sunlight may be protective against some internal malignancies. Because patients with these tumours are often vitamin D deficient, this has led some to propose that vitamin D supplementation will be beneficial in the treatment of these cancers. However, the results from already completed trials have been disappointing which has given weight to the argument that there must be something else about sunlight that explains its cancer-protecting properties.

An initial melanoma diagnosis may increase the subsequent risk of prostate cancer: Results from the New South Wales Cancer Registry

Emerging evidence suggests that a diagnosis of cutaneous melanoma (CM) may be associated with prostate cancer (PC) incidence. We examined if the incidence of CM was associated with an increased subsequent risk of PC. We used data from the New South Wales Cancer Registry for all CM and PC cases diagnosed between January 1972 and December 2008. We calculated the age standardized incidence ratio (SIR) and 95% confidence intervals (95% CI) for PC incidence following a CM diagnosis, applying age- and calendar- specific rates to the appropriate person years at risk. We determined rate ratio (RR) and 95% CI of PC incidence according to specified socio-demographic categories and disease related characteristics, using a negative binomial model. There were 143,594 men diagnosed with PC or CM in the study period and of these 101,198 and 42,396 were diagnosed with PC and CM, respectively, as first primary cancers. Risk of PC incidence increased following CM diagnosis (n = 2,114; SIR = 1.25; 95% CI:1.20.8-1.31: p < 0.0001), with the increased risk apparent in men diagnosed with localised CM (n = 1,862;SIR = 1.26; 95% CI:1.20-1.32). CM diagnosis increased the subsequent risk of PC incidence. This raises the potential for future PC risk to be discussed with newly diagnosed males with CM.

Associations between sun sensitive pigmentary genes and serum prostate specific antigen levels

Background

Melanoma and prostate cancer may share risk factors. This study examined the association between serum PSA levels, which is a risk factor for prostate cancer, and variants in some melanoma-associated pigmentary genes.

Methods

We studied participants, all aged 70+ years, in the Concord Health and Ageing in Men Project who had no history of prostatitis or received treatment for prostate disease (n = 1033). We genotyped variants in MC1R (rs1805007, rs1805008), ASIP (rs4911414, rs1015362), SLC45A2 (rs28777, rs16891982), IRF4 (rs12203592), TYRP1 (rs1408799), TYR (rs1126809, rs1042602), SLC24A2 (rs12896399), and OCA2 (rs7495174). Generalised linear dominant models with Poisson distribution, log link functions and robust variance estimators estimated adjusted percentage differences (%PSA) in mean serum PSA levels (ng/mL) between variant and wildtype (0%PSA = reference) genotypes, adjusting for age, body mass index, serum 25OHD levels and birth regions (Australia or New Zealand (ANZ), Europe or elsewhere).

Results

Serum PSA levels were strongly associated with advancing age and birth regions: mean PSA levels were lower in Europe-born (-29.7%) and elsewhere-born (-11.7%) men than ANZ-born men (reference). Lower %PSA was observed in men with variants in SLC45A2: rs28777 (-19.6;95%CI: -33.5, -2.7), rs16891982 (-17.3;95%CI:-30.4,-1.7) than in wildtype men (reference). There were significant interactions between birth regions and PSA levels in men with variants in MC1R (rs1805007; p-interaction = 0.0001) and ASIP (rs4911414; p-interaction = 0.007). For these genes %PSA was greater in ANZ-born men and lower in Europe- and elsewhere-born men with the variant than it was in wildtype men. In a post hoc analysis, serum testosterone levels were increased in men with MC1R rs1805007 and serum dihydrotestosterone in men with ASIP rs1015362.

Conclusion

Men with SNPs in SLC45A2, who have less sun sensitive skin, have lower PSA levels. Men with SNPs in MC1R and ASIP, who have more sun sensitive skin, and were born in ANZ, have higher PSA levels. Androgens may modify these apparent associations of pigmentary genes and sun exposure with PSA levels.

Impact

PSA levels and possibly prostate cancer risk may vary with sun sensitivity and sun exposure, the effects of which might be modified by androgen levels.

WOMEN IN CANCER THEMATIC REVIEW: New roles for nuclear receptors in prostate cancer

Prostate cancer has, for decades, been treated by inhibiting androgen signalling. This is effective in the majority of patients, but inevitably resistance develops and patients progress to life-threatening metastatic disease - hence the quest for new effective therapies for 'castrate-resistant' prostate cancer (CRPC). Studies into what pathways can drive tumour recurrence under these conditions has identified several other nuclear receptor signalling pathways as potential drivers or modulators of CRPC.The nuclear receptors constitute a large (48 members) superfamily of transcription factors sharing a common modular functional structure. Many of them are activated by the binding of small lipophilic molecules, making them potentially druggable. Even those for which no ligand exists or has yet been identified may be tractable to activity modulation by small molecules. Moreover, genomic studies have shown that in models of CRPC, other nuclear receptors can potentially drive similar transcriptional responses to the androgen receptor, while analysis of expression and sequencing databases shows disproportionately high mutation and copy number variation rates among the superfamily. Hence, the nuclear receptor superfamily is of intense interest in the drive to understand how prostate cancer recurs and how we may best treat such recurrent disease. This review aims to provide a snapshot of the current knowledge of the roles of different nuclear receptors in prostate cancer - a rapidly evolving field of research.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Designing an Internationally Accessible Web-Based Questionnaire to Discover Risk Factors for Amyotrophic Lateral Sclerosis: A Case-Control Study

Background

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease with a typical survival of three to five years. Epidemiological studies using paper-based questionnaires in individual countries or continents have failed to find widely accepted risk factors for the disease. The advantages of online versus paper-based questionnaires have been extensively reviewed, but few online epidemiological studies into human neurodegenerative diseases have so far been undertaken.

Objective

To design a Web-based questionnaire to identify environmental risk factors for ALS and enable international comparisons of these risk factors.

Methods

A Web-based epidemiological questionnaire for ALS has been developed based on experience gained from administering a previous continent-wide paper-based questionnaire for this disease. New and modified questions have been added from our previous paper-based questionnaire, from literature searches, and from validated ALS questionnaires supplied by other investigators. New criteria to allow the separation of familial and sporadic ALS cases have been included. The questionnaire addresses many risk factors that have already been proposed for ALS, as well as a number that have not yet been rigorously examined. To encourage participation, responses are collected anonymously and no personally identifiable information is requested. The survey is being translated into a number of languages which will allow many people around the world to read and answer it in their own language.

Results

After the questionnaire had been online for 4 months, it had 379 respondents compared to only 46 respondents for the same initial period using a paper-based questionnaire. The average age of the first 379 web questionnaire respondents was 54 years compared to the average age of 60 years for the first 379 paper questionnaire respondents. The questionnaire is soon to be promoted in a number of countries through ALS associations and disease registries.

Conclusions

Web-based questionnaires are a time- and resource-efficient method for performing large epidemiological studies of neurodegenerative diseases such as ALS. The ability to compare risk factors between different countries using the same analysis tool will be of particular value for finding robust risk factors that underlie ALS.

The consequences for human health of stratospheric ozone depletion in association with other environmental factors

Ozone depletion, climate and human health.

Prevention and early detection of prostate cancer

Prostate cancer is a common malignancy in men and the worldwide burden of this disease is rising. Lifestyle modifications such as smoking cessation, exercise, and weight control offer opportunities to reduce the risk of developing prostate cancer. Early detection of prostate cancer by prostate-specific antigen (PSA) screening is controversial, but changes in the PSA threshold, frequency of screening, and the use of other biomarkers have the potential to minimise the overdiagnosis associated with PSA screening. Several new biomarkers for individuals with raised PSA concentrations or those diagnosed with prostate cancer are likely to identify individuals who can be spared aggressive treatment. Several pharmacological agents such as 5α-reductase inhibitors and aspirin could prevent development of prostate cancer. In this Review, we discuss the present evidence and research questions regarding prevention, early detection of prostate cancer, and management of men either at high risk of prostate cancer or diagnosed with low-grade prostate cancer.

Sunlight exposure during leisure activities and risk of prostate cancer in Montréal, Canada, 2005-2009

Background

Prostate cancer (PCa) is the leading cause of cancer in men in many developed countries, but no modifiable risk factors have been identified. A handful of analytical studies have suggested a possible etiological role for sunlight exposure. We report here on the association between leisure-time sunlight exposure during adulthood and PCa risk in the context of a population-based case–control study.

Methods

In all, 1,904 PCa cases were ascertained across Montreal French hospitals between 2005 and 2009. Concurrently, 1,962 population controls, frequency matched to cases by age (±5 years), were selected from the electoral list for French-speakers in Greater Montreal. Interviews elicited the frequency of engagement in any leisure activity during adulthood. This was used to derive cumulative sunlight exposure indices: a cumulative number of leisure activities events entailing sunlight exposure and a cumulative duration of sunlight exposure during leisure activities. Unconditional logistic regression was conducted to yield odds ratios (OR) and 95% confidence intervals (CI) for estimating the association between sunlight exposure indices and PCa risk, adjusting for age, ancestry, family history of PCa, PCa screening, education, solar protection, body mass index and physical activity.

Results

Compared with men in the upper quartile category for the number of sunlight exposure events, men never exposed during leisure time had an OR of 1.32 (95% CI: 0.82-2.14). ORs were 1.11, 0.91 and 1.00 for the first to the third quartiles of exposure, respectively. Similar results were observed for cumulative duration of exposure to sunlight, and by PCa aggressiveness.

Conclusion

These findings provide little evidence of an association between sunlight exposure during leisure-time and PCa risk. Men with no sunlight exposure appeared at somewhat higher risks but none of the estimates achieved statistical significance.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-756) contains supplementary material, which is available to authorized users.

The association between personal sun exposure, serum vitamin D and global methylation in human lymphocytes in a population of healthy adults in South Australia

BACKGROUND

There is a positive association between solar UV exposure and micronucleus frequency in peripheral blood lymphocytes (PBL) and this association may be stronger when serum vitamin D (25(OH)D) levels are insufficient (<50 nmol/L). Micronucleus formation can result from global hypomethylation of DNA repeat sequences. The aim of this analysis was to evaluate the relationship between solar UV exposure and methylation pattern in LINE-1 repetitive elements in PBL DNA and to see if serum 25(OH)D levels modify it.

METHOD

Personal solar UV exposure was estimated from hours of outdoor exposure over 6 weeks recalled at the time of blood collection in 208 male and female participants living in South Australia. Methylation in LINE-1 repetitive elements was assessed in PBL using pyrosequencing.

RESULTS

Methylation in LINE-1 decreased with increasing solar UV exposure (% decrease = 0.5% per doubling of sUV; 95%CI: -0.7 to -0.2 p(value) = 0.00003). Although there was no correlation between LINE-1 methylation and micronucleus frequency, there was a 4.3% increase (95%CI: 0.6-8.1 p-value = 0.02) in nucleoplasmic bridges and a 4.3% increase in necrosis (CI: 1.9-6.8 p-value = 0.0005) for every 1% increase in LINE-1 methylation. Serum 25(OH)D was not associated with DNA methylation; or did it modify the association of solar UV with DNA methylation.

CONCLUSION

Exposure to solar UV radiation may reduce DNA methylation in circulating lymphocytes. This association does not appear to be influenced or mediated by vitamin D status.

VDR activity is differentially affected by Hic-5 in prostate cancer and stromal cells

Patients with prostate cancer treated with androgen deprivation therapy (ADT) eventually develop castrate-resistant prostate cancer (CRPC). 1,25-Dihydroxyvitamin D3 (1,25D3/calcitriol) is a potential adjuvant therapy that confers antiproliferative and pro-differentiation effects in vitro, but has had mixed results in clinical trials. The impact of the tumor microenvironment on 1,25D3 therapy in patients with CRPC has not been assessed. Transforming growth factor β (TGFβ), which is associated with the development of tumorigenic "reactive stroma" in prostate cancer, induced vitamin D3 receptor (VDR) expression in the human WPMY-1 prostate stromal cell line. Similarly, TGFβ enhanced 1,25D3-induced upregulation of CYP24A1, which metabolizes 1,25D3 and thereby limits VDR activity. Ablation of Hic-5, a TGFβ-inducible nuclear receptor coregulator, inhibited basal VDR expression, 1,25D3-induced CYP24A1 expression and metabolism of 1,25D3 and TGFβ-enhanced CYP24A1 expression. A Hic-5-responsive sequence was identified upstream (392-451 bp) of the CYP24A1 transcription start site that is occupied by VDR only in the presence of Hic-5. Ectopic expression of Hic-5 sensitized LNCaP prostate tumor cells to growth-inhibitory effects of 1,25D3 independent of CYP24A1. The sensitivity of Hic-5-expressing LNCaP cells to 1,25D3-induced growth inhibition was accentuated in coculture with Hic-5-ablated WPMY-1 cells. Therefore, these findings indicate that the search for mechanisms to sensitize prostate cancer cells to the antiproliferative effects of VDR ligands needs to account for the impact of VDR activity in the tumor microenvironment.

IMPLICATIONS

Hic-5 acts as a coregulator with distinct effects on VDR transactivation, in prostate cancer and stromal cells, and may exert diverse effects on adjuvant therapy designed to exploit VDR activity in prostate cancer.

Prostate cancer: is it time to expand the research focus to early-life exposures?

Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have yet been identified. One possible reason for this may be the dearth of epidemiological research on exposures experienced early in life, when the immature prostate may be more susceptible to carcinogenic exposures. In this Opinion article, we summarize the rationale for studying early-life exposures, describe the small body of early-life research and its associated challenges, and point to solutions for future research.

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.