Serum 25-hydroxyvitamin D3 levels and vitamin D receptor variants in melanoma patients from the Mediterranean area of Barcelona

Malignant Melanoma: An Overview, New Perspectives, and Vitamin D Signaling

Melanoma, originating through malignant transformation of melanin-producing melanocytes, is a formidable malignancy, characterized by local invasiveness, recurrence, early metastasis, resistance to therapy, and a high mortality rate. This review discusses etiologic and risk factors for melanoma, diagnostic and prognostic tools, including recent advances in molecular biology, omics, and bioinformatics, and provides an overview of its therapy. Since the incidence of melanoma is rising and mortality remains unacceptably high, we discuss its inherent properties, including melanogenesis, that make this disease resilient to treatment and propose to use AI to solve the above complex and multidimensional problems. We provide an overview on vitamin D and its anticancerogenic properties, and report recent advances in this field that can provide solutions for the prevention and/or therapy of melanoma. Experimental papers and clinicopathological studies on the role of vitamin D status and signaling pathways initiated by its active metabolites in melanoma prognosis and therapy are reviewed. We conclude that vitamin D signaling, defined by specific nuclear receptors and selective activation by specific vitamin D hydroxyderivatives, can provide a benefit for new or existing therapeutic approaches. We propose to target vitamin D signaling with the use of computational biology and AI tools to provide a solution to the melanoma problem.

Vitamin D and Cutaneous Melanoma Risk: An Umbrella Review of Systematic Reviews and Meta-Analyses

Background: Vitamin D (VitD) properties can impact cancer cells. Despite the documented link between VitD levels and prevalence of several cancer types, conflicting findings have been reported for cutaneous melanoma (CM). Objective: This overview aims to compile the evidence from existing systematic reviews and meta-analyses, emphasizing the relationships between VitD serum levels, intake, receptor (VDR) gene polymorphisms, and CM risk. Methods: A literature search in electronic databases was conducted, based on certain inclusion criteria. Results: Twenty-one studies were included. Conflicting evidence between high VitD serum levels, dietary/supplementary intake, and CM risk is highlighted. VDR polymorphisms may play a role in the intricate CM pathogenesis. Also, high serum levels of VitD are associated with improved CM prognosis. Conclusions: This overview showed that the impact of VitD on CM is not clear, and thus further research is suggested to explore its true effect size on CM risk.

Vitamin D deficiency in melanoma patients is associated with worse overall survival: a retrospective cohort study

Recent interest has emerged in the protective role of vitamin D in melanoma survival and is the subject of multiple studies with heterogeneous results. Here, we present a retrospective cohort study of 264 patients with invasive melanoma from a tertiary university hospital. The aim of the study was to analyze the relationship between vitamin D levels and prognosis of melanoma patients. We found that lower vitamin D levels are independently associated with worse overall survival in melanoma patients in concordance with previous studies on other populations. Vitamin D deficiency could play a survival role in melanoma patients,. Future prospective studies are needed to investigate the effect of vitamin D supplementation on melanoma outcomes.

Is ultraviolet radiation avoidance affecting bone health in melanoma patients?

BACKGROUND

Ultraviolet (UV) radiation has numerous beneficial effects on human health, including stimulating vitamin D and serotonin production and immuno-regulatory activities. Conversely, UV radiation is also classified as a group one carcinogen by the International Agency for Research on Cancer.

PURPOSE

To investigated the effects of UV radiation avoidance in melanoma patients in terms of vitamin D levels but also of bone mineral density and trabecular bone microarchitecture.

METHODS

We conducted an observational study investigating the effects of UV radiation avoidance in 31 melanoma patients in terms of vitamin D levels but also of bone mineral density and trabecular bone microarchitecture by using dual-energy X-ray absorptiometry scan. Data were compared with two control groups of healthy subjects, who were chronically exposed or not exposed to UV radiation during their lifetime.

RESULTS

Melanoma patients had on average slightly lower levels of vitamin D, without reaching statistical significance (P = .135). No significant difference was found across the three groups on T-scores of femoral neck (P = .544), of total hip (P = .617) and of lumbar spine P = .155). No significant difference was found on and trabecular bone score across exposure groups (P = .895).

CONCLUSION

UV radiation avoidance does not seem to significantly impact vitamin D levels nor bone health in melanoma patients. Thus, UV protective behavior is advisable for all melanoma patients.

Solar UV Exposure and Mortality from Skin Tumors: An Update

Solar UV exposure is critical and complex in the etiology and prognosis of skin cancer, particularly cutaneous malignant melanoma. Sun exposure and one of its "derivatives," vitamin D, have been implicated in protection against mortality from melanoma. However, the relationships are inconsistent. At this time, it is not possible to make clear recommendations for or against sun exposure in relationship to melanoma prognosis. However, this relationship deserves continued exploration.

Genetic polymorphisms in vitamin D pathway influence 25(OH)D levels and are associated with atopy and asthma

Background

Vitamin D deficiency or insufficiency, has been associated with atopy and lack of asthma control. Our objective was to investigate associations between variants in genes of vitamin D pathway with serum levels of 25-hydroxyvitamin D (25(OH)D), atopy, asthma and asthma severity in teenagers from Northeast Brazil.

Methods

This is a cross sectional study nested in a cohort population of asthma. 25(OH)D was quantified from 968 of 11–17 years old individuals by ELISA. Asthma diagnosis was obtained by using the ISAAC Phase III questionnaire. Specific IgE was determined by ImmunoCAP; genotyping was performed using the 2.5 HumanOmni Biochip from Illumina. Statistical analyses were performed in PLINK 1.07 and SPSS 22.1.

Results

After quality control, 104 Single Nucleotides Variants (SNVs) in vitamin D pathway genes, typed in 792 individuals, were included in the analysis. The allele A of rs10875694 on VDR was positively associated with atopy (OR = 1.35; 95% CI 1.01–1.81). The allele C of rs9279 on VDR, was negatively associated with asthma risk (OR = 0.66; 95% CI 0.45–0.97), vitamin D insufficiency (OR = 0.78; 95% CI 0.70–0.96) and higher VDR expression. Two variants in VDR were associated with asthma severity, the allele A of rs2189480 (OR = 0.34; 95% CI 0.13–0.89) and the allele G of rs4328262 (OR = 3.18; 95% CI 1.09–9.28). The combination of variants in CYP2R1 and CYP24A1 (GAC, to rs10500804, rs12794714 and rs3886163, respectively) was negatively associated with vitamin D production (β = − 1.24; 95% CI − 2.42 to − 0.06).

Conclusions

Genetic variants in the vitamin D pathway affect vitamin D serum levels and, thus, atopy and asthma.

The association between serum vitamin D level and risk and prognosis of melanoma: a systematic review and meta-analysis

BACKGROUND

Vitamin D has antineoplastic effects, but the synthesis of vitamin D requires ultraviolet radiation, a known risk factor for melanoma.

OBJECTIVE

To investigate the correlations between serum vitamin D levels and risk and prognosis of melanoma.

METHODS

A systematic review and meta-analysis were conducted. Online databases were searched on 31 Oct 2018.

RESULTS

Twenty-five studies with a total of 11166 patients with melanoma were included. There was no significant difference in serum vitamin D levels between patients with melanoma and controls [standardized mean difference (SMD), -0.185; 95% confidence interval (CI), -0.533 to 0.162]. However, the prevalence of vitamin D deficiency was significantly higher in patients with melanoma than that in controls (odds ratio, 2.115; 95% CI, 1.151-3.885). In terms of prognosis, serum vitamin D levels were significantly higher in melanoma patients with lower Breslow thickness (≦1 vs. >1 mm: SMD, 0.243; 95% CI, 0.160-0.327). Moreover, melanoma patients with lower vitamin D levels had a significantly higher mortality rate (hazard ratio, 1.558; 95% CI, 1.258-1.931).

CONCLUSIONS

Vitamin D deficiency is associated with higher Breslow thickness and mortality in melanoma patients.

Vitamin D and its low calcemic analogs modulate the anticancer properties of cisplatin and dacarbazine in the human melanoma A375 cell line

Melanoma represents a significant challenge in cancer treatment due to the high drug resistance of melanomas and the patient mortality rate. This study presents data indicating that nanomolar concentrations of the hormonally active form of vitamin D, 1α,25-dihydroxyvitamin D3 [1α,25(OH)₂D3], its non-calcemic analogues 20S-hydroxyvitamin D3 and 21-hydroxypregnacalciferol, as well as the low-calcemic synthetic analog calcipotriol, modulate the efficacy of the anticancer drugs cisplatin and dacarbazine. It was observed that vitamin D analogs sensitized melanoma A375 cells to hydrogen peroxide used as an inducer of oxidative stress. On the other hand, only 1α,25(OH)₂D3 resulted in a minor, but significant effect on the proliferation of melanoma cells treated simultaneously with dacarbazine, but not cisplatin. Notably, cisplatin (300 µM) exhibited a higher overall antiproliferative activity than dacarbazine. Cisplatin treatment of melanoma cells resulted in an induction of apoptosis as demonstrated by flow cytometry (accumulation of cells at the subG₁ phase of the cell cycle), whereas dacarbazine caused G₁/G₀ cell cycle arrest, with the effects being improved by pre-treatment with vitamin D analogs. Treatment with cisplatin resulted in an initial increase in the level of reactive oxygen species (ROS). Dacarbazine caused transient stimulation of ROS levels and the mitochondrial membrane potential (Δψ_m) (after 1 or 3 h of treatment, respectively), but the effect was not detectable following prolonged (24 h) incubation with the drug. Vitamin D exhibited modulatory effects on the cells treated with dacarbazine, decreasing the half maximal inhibitory concentration (IC₅₀) for the drug, stimulating G₁/G₀ arrest and causing a marked decrease in Δψ_m. Finally, cisplatin, dacarbazine and 1α,25(OH)₂D3 displayed modulatory effects on the expression of ROS and vitamin D-associated genes in the melanoma A375 cells. In conclusion, nanomolar concentrations of 1,25(OH)₂D₃ only had minor effects on the proliferation of melanoma cells treated with dacarbazine, decreasing the relative IC₅₀ value. However, co-treatment with vitamin D analogs resulted in the modulation of cell cycle and ROS responses, and affected gene expression, suggesting possible crosstalk between the signaling pathways of vitamin D and the anticancer drugs used in this study.

Vitamin D deficiency in solid-organ transplant recipients from a Spanish Mediterranean population

BACKGROUND

Solid-organ transplant recipients (SOTRs) are at risk of developing vitamin D deficiency, mainly caused by reduced sunlight exposure with subsequent low vitamin D synthesis in the skin.

AIM

To analyse whether SOTRs from a Spanish Mediterranean region were vitamin D-deficient.

METHODS

This was a cross-sectional, descriptive and observational study in a transplantation-specialized Dermatological Unit from a Mediterranean area to determine the calcidiol levels of a cohort of 78 consecutively attending patients not receiving vitamin D supplements. Serum 25(OH)D₃ levels were determined and clinical characteristics were collected. Logistic regression analysis was used to analyse variables associated with dichotomized 25(OH)D₃ levels (≤ or > 10 ng/mL).

RESULTS

The cohort comprised 30 lung, 29 kidney and 19 liver transplant recipients. Mean calcidiol was 18 ± 9 ng/mL. Deficiency of 25(OH)D₃ was present in 19% of patients, while 68% had insufficient levels and 13% had sufficient levels. Following multivariate logistic regression analysis, the season of blood sampling remained the only predictor of deficient 25(OH)D₃ levels.

CONCLUSION

Despite living in a mid-latitude country with sunny weather, our SOTR population was at high risk of developing hypovitaminosis D, especially in autumn/winter. Avoiding sun exposure is important to prevent skin cancer, but careful monitoring of vitamin D status is recommended, with supplementation if hypovitaminosis D is detected.

25-hydroxyvitamin D serum levels in patients with high risk resected melanoma treated in an adjuvant bevacizumab trial

BACKGROUND

Studies evaluating a relationship of vitamin D in patients with primary melanoma have consistently identified an inverse correlation with Breslow thickness, but an inconsistent impact on survival. Vitamin D in later stages of melanoma has been less studied.

METHODS

Vitamin D was measured in serum from 341 patients with resected stage IIB-IIIC melanoma recruited to the AVAST-M adjuvant melanoma randomised trial, collected prior to randomisation, then at 3 and 12 months. Vitamin D levels were compared with patient demographics, known melanoma prognostic factors, disease-free interval (DFI) and overall survival (OS).

RESULTS

A total of 73% patients had stage III melanoma, 32% were enroled (and therefore tested) >1 year after primary melanoma diagnosis. Median pre-randomisation vitamin D level was 56.5 (range 12.6-189.0 nmol/L). Vitamin D levels did not significantly vary over 12 months (p = 0.24). Individual pre-randomisation vitamin D levels did not differ significantly for Breslow thickness, tumour ulceration, or disease stage. Neither did pre-randomisation vitamin D predict for DFI (HR = 0.98 per 10 nmol/L increase; 95% confidence interval (CI) 0.93-1.04, p = 0.59) or OS (HR = 0.96 per 10 nmol/L increase, 95% CI 0.90-1.03, p = 0.31). For stage II patients, DFI improved with higher pre-randomisation vitamin D levels for those on bevacizumab (HR = 0.74 per 10 nmol nmol/L increase; 95% CI 0.56-0.97), but not for the observation arm (HR = 1.07 per 10 nmol/L increase; 95% CI 0.85-1.34).

CONCLUSIONS

In this stage II/III melanoma cohort, vitamin D did not correlate with known prognostic markers, nor predict for DFI or OS, but there was some evidence of benefit for patients with stage II disease treated with bevacizumab.

Mechanisms and prevention of UV-induced melanoma

Melanoma is the deadliest form of skin cancer and its incidence is rising, creating a costly and significant clinical problem. Exposure to ultraviolet (UV) radiation, namely UVA (315-400 nm) and UVB (280-315 nm), is a major risk factor for melanoma development. Cumulative UV radiation exposure from sunlight or tanning beds contributes to UV-induced DNA damage, oxidative stress, and inflammation in the skin. A number of factors, including hair color, skin type, genetic background, location, and history of tanning, determine the skin's response to UV radiation. In melanocytes, dysregulation of this UV radiation response can lead to melanoma. Given the complex origins of melanoma, it is difficult to develop curative therapies and universally effective preventative strategies. Here, we describe and discuss the mechanisms of UV-induced skin damage responsible for inducing melanomagenesis, and explore options for therapeutic and preventative interventions.

Vitamin D signaling and melanoma: role of vitamin D and its receptors in melanoma progression and management

Ultraviolet B (UVB), in addition to having carcinogenic activity, is required for the production of vitamin D3 (D3) in the skin which supplies >90% of the body's requirement. Vitamin D is activated through hydroxylation by 25-hydroxylases (CYP2R1 or CYP27A1) and 1α-hydroxylase (CYP27B1) to produce 1,25(OH)₂D3, or through the action of CYP11A1 to produce mono-di- and trihydroxy-D3 products that can be further modified by CYP27B1, CYP27A1, and CYP24A1. The active forms of D3, in addition to regulating calcium metabolism, exert pleiotropic activities, which include anticarcinogenic and anti-melanoma effects in experimental models, with photoprotection against UVB-induced damage. These diverse effects are mediated through an interaction with the vitamin D receptor (VDR) and/or as most recently demonstrated through action on retinoic acid orphan receptors (ROR)α and RORγ. With respect to melanoma, low levels of 25(OH)D are associated with thicker tumors and reduced patient survival. Furthermore, single-nucleotide polymorphisms of VDR and the vitamin D-binding protein (VDP) genes affect melanomagenesis or disease outcome. Clinicopathological analyses have shown positive correlation between low or undetectable expression of VDR and/or CYP27B1 in melanoma with tumor progression and shorter overall (OS) and disease-free survival (DFS) times. Paradoxically, this correlation was reversed for CYP24A1 (inactivating 24-hydroxylase), indicating that this enzyme, while inactivating 1,25(OH)₂D3, can activate other forms of D3 that are products of the non-canonical pathway initiated by CYP11A1. An inverse correlation has been found between the levels of RORα and RORγ expression and melanoma progression and disease outcome. Therefore, we propose that defects in vitamin D signaling including D3 activation/inactivation, and the expression and activity of the corresponding receptors, affect melanoma progression and the outcome of the disease. The existence of multiple bioactive forms of D3 and alternative receptors affecting the behavior of melanoma should be taken into consideration when applying vitamin D management for melanoma therapy.

High serum vitamin D level correlates with better prognostic indicators in primary melanoma: A pilot study

BACKGROUND/OBJECTIVES

Sunlight is a major risk factor for cutaneous melanoma. However, its interaction with melanoma is complex. In particular, vitamin D is a UVB-derived hormone that has been shown to have anti-cancer effects. In this retrospective pilot study we sought to determine an association between the clinicopathological features of melanoma and the patients' corresponding serum vitamin D level.

METHODS

In total, 109 primary melanomas diagnosed between 2001 and 2013 were retrospectively identified from our institutional database with a corresponding 25-hydroxyvitamin D3 level estimated within 6 months of diagnosis. Tumour, clinical (age, sex, tumour location) and pathological (thickness, mitosis, ulceration, Clark level, subtype, metastatic status) parameters were correlated with vitamin D. For statistical analysis, an unpaired Student's t-test and anova was used for categorical variables, and Spearman's correlation for continuous variables.

RESULTS

Vitamin D level was inversely associated with Breslow thickness as a dichotomous, categorical and continuous variable. The association remained significant when controlled for patient's age and sex (P = 0.026). Vitamin D was higher in non-ulcerated tumours compared with ulcerated tumours (P = 0.006) and in tumours with mitotic rate <1/mm² compared with ≥1/mm² (P = 0.036). A significant association was found between vitamin D level and tumour histological subtype (P = 0.019). On subgroup analysis, significant associations were found between superficial spreading melanoma (SSM) and nodular melanoma (P = 0.026), and SSM and acral lentiginous melanoma (P = 0.007).

CONCLUSION

A high vitamin D status may benefit prognosis in patients diagnosed with primary melanoma. A prospective cohort analysis with a large sample and controlled for other vitamin D confounders would validate these findings.

Study and evaluation the impact of vitamin D receptor variants on the risk of type 2 diabetes mellitus in Han Chinese

BACKGROUND

Vitamin D and the vitamin D receptor (VDR) are associated with susceptibility to type 2 diabetes mellitus (T2DM). The purpose of the present study was to screen more single nucleotide polymorphisms (SNPs) of VDR and assess their effects on the risk of T2DM in Han Chinese.

METHOD

Four SNPs were genotyped in 1191 individuals (397 cases, 794 controls). Allele frequencies and genotype distributions were analyzed. Effects were investigated by evaluating genotype distribution with regard to phenotypes, insulin resistance, and β-cell function. Haplotype analysis and gene risk score (GRS) were used to evaluate the combined and additive roles of VDR SNPs on T2DM pathogenesis.

RESULTS

There was a significant association between rs739837 and T2DM in two models and allele frequency distribution. The novel locus rs2239179 differed significantly between cases and controls, especially in males and those aged >55 years, in three models and allele frequency distribution. The TT genotype of rs739837 was associated with higher triglyceride than GG and TG genotypes, and higher total cholesterol levels than the GG genotype. Compared with the GTGA haplotype, the GCGG haplotype reduced the risk of T2DM. Trend Chi-squared tests showed that there was significant association between the weighted GRS and the risk of T2DM (P_trend  = 0.034).

CONCLUSION

This study provides novel evidence that rs739837 is associated with lipid metabolism in T2DM patients. The rs739837 and rs2239179 SNPs were associated with the risk of T2DM in Han Chinese. The VDR SNPs had combined and additive effects on the risk of T2DM.

25-Hydroxyvitamin D in Patients With Melanoma and Factors Associated With Inadequate Levels

INTRODUCTION AND OBJECTIVES

Patients with melanoma appear to take extreme sun-protection measures, which could influence 25-hydroxyvitamin D [25(OH)D] levels. The aim of this study was to measure 25(OH)D levels in patients with cutaneous melanoma and identify factors associated with inadequate levels.

MATERIAL AND METHODS

Over a period of 1 year, we prospectively measured serum 25(OH)D in patients with cutaneous melanoma and used logistic regression analysis to identify environmental, phenotypic, and genotypic factors that were associated with insufficient and deficient levels.

RESULTS

Of 215 patients analyzed, 8.8% had deficient 25(OH)D levels (<10ng/mL) and just 24.7% had normal levels. Insufficient levels (<30ng/mL) were associated with obesity (odds ratio [OR], 4.2; 95% confidence interval [CI], 1.3-13.3) and blood sampling in autumn/winter (OR, 2.1; 95% CI, 1.1-4). Deficient levels (<10ng/mL) were associated with obesity (OR, 7.1; 95% CI, 1.1-46.9), blood sampling in autumn/winter (OR, 9.0; 95% CI, 1.7-47.0), absence of freckles (OR, 5.4; 95% CI, 1.2-23.4), and, with marginal significance, the presence of fewer than 2 nonsynonymous melanocortin-1 receptor (MC1R) polymorphisms (OR, 5.0; 95% CI, 0.9-28.9).

LIMITATIONS

Some factors related to 25(OH)D levels, such as food, were not included in the analyses.

CONCLUSIONS

25(OH)D levels should be monitored in patients with melanoma and the need for oral supplements should be contemplated where appropriate.

Characterization of individuals at high risk of developing melanoma in Latin America: bases for genetic counseling in melanoma

Purpose:

CDKN2A is the main high-risk melanoma-susceptibility gene, but it has been poorly assessed in Latin America. We sought to analyze CDKN2A and MC1R in patients from Latin America with familial and sporadic multiple primary melanoma (SMP) and compare the data with those for patients from Spain to establish bases for melanoma genetic counseling in Latin America.

Genet Med18 7, 727–736.

Methods:

CDKN2A and MC1R were sequenced in 186 Latin American patients from Argentina, Brazil, Chile, Mexico, and Uruguay, and in 904 Spanish patients. Clinical and phenotypic data were obtained.

Genet Med18 7, 727–736.

Results:

Overall, 24 and 14% of melanoma-prone families in Latin America and Spain, respectively, had mutations in CDKN2A. Latin American families had CDKN2A mutations more frequently (P = 0.014) than Spanish ones. Of patients with SMP, 10% of those from Latin America and 8.5% of those from Spain had mutations in CDKN2A (P = 0.623). The most recurrent CDKN2A mutations were c.-34G>T and p.G101W. Latin American patients had fairer hair (P = 0.016) and skin (P < 0.001) and a higher prevalence of MC1R variants (P = 0.003) compared with Spanish patients.

Genet Med18 7, 727–736.

Conclusion:

The inclusion criteria for genetic counseling of melanoma in Latin America may be the same criteria used in Spain, as suggested in areas with low to medium incidence, SMP with at least two melanomas, or families with at least two cases among first- or second-degree relatives.

Genet Med18 7, 727–736.

Vitamins and Melanoma

A tremendous amount of information was published over the past decades in relation to the role of vitamins in various neoplastic diseases. In particular, several studies showed an inverse relationship between selected vitamins intake and cancer risk. In this review we will focus on the role played by vitamins in melanoma with particular regard to vitamin A, D, K, E and C. Given that vitamin supplementation is easy, convenient, and readily accepted by patients, in the future the use of vitamins in chemoprevention and therapy of melanoma could be encouraged if supported by pre-clinical and clinical evidence.

Serum level of vitamin D3 in cutaneous melanoma

OBJECTIVE

To compare the level of vitamin D3 in cutaneous melanoma patients, with or without disease activity, with reference values and with patients from a general hospital.

METHODS

The serum levels of vitamin D3 were measured in cutaneous melanoma patients, aged 20 to 88 years, both genders, from January 2010 to December 2013. The samples from the general group were processed at Hospital Israelita Albert Einstein (control group). Data analysis was performed using the Statistics software.

RESULTS

A total of 100 patients were studied, 54 of them men, with mean age of 54.67 years, and 95 Caucasian. Out of these 100 patients, 17 had active disease. The average levels of vitamin D3 in the melanoma patients were lower than the level considered sufficient, but above the average of the control group. Both groups (with or without active disease) of patients showed a similar distribution of vitamin D3 deficiency.

CONCLUSION

Vitamin D3 levels in melanoma patients were higher than those of general patients and lower than the reference level. If the reference values are appropriate, a large part of the population had insufficient levels of vitamin D, including those with melanoma, or else, this standard needs to be reevaluated. No difference in vitamin D3 levels was found among melanoma patients with or without active disease. More comprehensive research is needed to assess the relation between vitamin D and melanoma.

Vitamin D and melanoma and non-melanoma skin cancer risk and prognosis: a comprehensive review and meta-analysis

Vitamin D is formed mainly in the skin upon exposure to sunlight and can as well be taken orally with food or through supplements. While sun exposure is a known risk factor for skin cancer development, vitamin D exerts anti-proliferative and pro-apoptotic effects on melanocytes and keratinocytes in vitro. To clarify the role of vitamin D in skin carcinogenesis, we performed a review of the literature and meta-analysis to evaluate the association of vitamin D serum levels and dietary intake with cutaneous melanoma (CM) and non-melanoma skin cancer (NMSC) risk and melanoma prognostic factors. Twenty papers were included for an overall 1420 CM and 2317 NMSC. The summary relative risks (SRRs) from random effects models for the association of highest versus lowest vitamin D serum levels was 1.46 (95% confidence interval (CI) 0.60-3.53) and 1.64 (95% CI 1.02-2.65) for CM and NMSC, respectively. The SRR for the highest versus lowest quintile of vitamin D intake was 0.86 (95% CI 0.63-1.13) for CM and 1.03 (95% CI 0.95-1.13) for NMSC. Data were suggestive of an inverse association between vitamin D blood levels and CM thickness at diagnosis. Further research is needed to investigate the effect of vitamin D on skin cancer risk in populations with different exposure to sunlight and dietary habits, and to evaluate whether vitamin D supplementation is effective in improving CM survival.