Melanoma risk for CDKN2A mutation carriers who are relatives of population-based case carriers in Australia and the UK.

BACKGROUND: CDKN2A mutations confer a substantial risk of cutaneous melanoma; however, the magnitude of risk is uncertain. METHODS: The study estimated the hazard ratio (HR) and the average age specific cumulative risk (ie, penetrance) of reported melanoma for CDKN2A mutation carriers in case families using a modified segregation analysis of the first and higher degree relatives of 35 population-based cases. The study sample included 223 relatives of 13 melanoma cases diagnosed when aged 18-39 years from Melbourne, Sydney and Brisbane, Australia, and 322 relatives of 22 melanoma cases diagnosed at any age from Yorkshire, UK. RESULTS: The estimated HR for melanoma for mutation carriers relative to the general population decreased with regions of increasing ambient ultraviolet (UV) irradiance, being higher for the UK than Australia (87, 95% CI 50 to 153 vs 31, 95% CI 20 to 50, p=0.008), and across Australia, 49 (95% CI 24 to 98) for Melbourne, 44 (95% CI 22 to 88) for Sydney, and 9 (95% CI 2 to 33) for Brisbane (p=0.02). Penetrance did not differ by geographic region. It is estimated that 16% (95% CI 10% to 27%) of UK and 20% (95% CI 13% to 30%) of Australian CDKN2A mutation carriers would be diagnosed with melanoma by age 50 years, and 45% (95% CI 29% to 65%) and 52% (95% CI 37% to 69%), respectively, by age 80 years. CONCLUSIONS: Contrary to the strong association between UV radiation exposure and melanoma risk for the general population, CDKN2A mutation carriers appear to have the same cumulative risk of melanoma irrespective of the ambient UV irradiance of the region in which they live.

The determinants of serum vitamin D levels in participants in a melanoma case-control study living in a temperate climate.

BACKGROUND: We report the determinants of serum levels of vitamin D in a U.K. melanoma case-control study benefitting from detailed exposure and genotyping data. METHODS: Sun exposure, supplemental vitamin D, and SNPs reported to be associated with serum levels were assessed as predictors of a single serum 25-hydroxyvitamin D3 measurement adjusted for season, age, sex, and body mass index. RESULTS: Adjusted analyses showed that vitamin D levels were sub-optimal especially in the sun-sensitive individuals (-2.61 nmol/L, p = 0.03) and for inheritance of a genetic variant in the GC gene coding for the vitamin D-binding protein (-5.79 for heterozygotes versus wild type, p = <0.0001). Higher levels were associated with sun exposure at the weekend in summer (+4.71 nmol/L per tertile, p = <0.0001), and on hot holidays (+4.17 nmol/L per tertile, p = <0.0001). In smoothed scatter plots, vitamin D levels of 60 nmol/L in the non-sun-sensitive individuals were achieved after an average 6 h/day summer weekend sun exposure but not in the sun-sensitive individuals. Users of supplements had levels on average 11.0 nmol/L higher, p = <0.0001, and achieved optimal levels irrespective of sun exposure. CONCLUSIONS: Sun exposure was associated with increased vitamin D levels, but levels more than 60 nmol/L were reached on average only in individuals reporting lengthy exposure (≥12 h/weekend). The sun-sensitive individuals did not achieve optimal levels without supplementation, which therefore should be considered for the majority of populations living in a temperate climate and melanoma patients in particular. Inherited variation in genes such as GC is a strong factor, and carriers of variant alleles may therefore require higher levels of supplementation.

A comparison of CDKN2A mutation detection within the Melanoma Genetics Consortium (GenoMEL).

CDKN2A is the major melanoma susceptibility gene so far identified, but only 40% of three or more case families have identified mutations. A comparison of mutation detection rates was carried out by "blind" exchange of samples across GenoMEL, the Melanoma Genetics Consortium, to establish the false negative detection rates. Denaturing high performance liquid chromatography (DHPLC) screening results from 451 samples were compared to screening data from nine research groups in which the initial mutation screen had been done predominantly by sequencing. Three samples with mutations identified at the local centres were not detected by the DHPLC screen. No additional mutations were detected by DHPLC. Mutation detection across groups within GenoMEL is carried out to a consistently high standard. The relatively low rate of CDKN2A mutation detection is not due to failure to detect mutations and implies the existence of other high penetrance melanoma susceptibility genes.

A mutation hotspot at the p14ARF splice site.

Germline mutations of CDKN2A that affect the p16INK4a transcript have been identified in numerous melanoma pedigrees worldwide. In the UK, over 50% of pedigrees with three or more cases of melanoma have been found to carry mutations of CDKN2A. Mutations that affect p14ARF exon 1beta exclusively are very rare. This has led to the suggestion that it is p16INK4a and not p14ARF that plays the critical role in melanoma predisposition. We report the identification of a cluster of five different germline mutations at the p14ARF exon 1beta splice donor site in melanoma pedigrees. All the five splice site variants showed evidence of being causal mutations. Three of the variants were demonstrated to result in aberrant splicing of the p14ARF mRNA, confirming their role in melanoma predisposition. No other point mutations were identified in the coding region of p14ARF. The p14ARF transcript of CDKN2A is clearly important in disease predisposition in a subset of melanoma pedigrees. Curiously, the only mutations so far reported to affect p14ARF exon 1beta exclusively have been knockout mutations. Further investigation into the spectrum of mutations observed in this gene may help clarify the exact role of p14ARF in melanoma predisposition.

Diet and genetic factors associated with iron status in middle-aged women.

BACKGROUND: Gene mutations associated with iron overload have been identified. How food and nutrient intakes affect iron status in persons who may be at risk of iron overload because their genetic status is unknown. OBJECTIVE: The objective was to determine the relation between food and nutrient intakes, HFE genotype, and iron status. Foods and nutrients associated with iron stores, with adjustment for gene mutations associated with hemochromatosis, were explored. DESIGN: A prospective cohort of women aged 35-69 y (the UK Women's Cohort Study) provided information on diet through a questionnaire and food diary; 6779 women in the cohort provided cheek cell samples, blood samples, or both, which were genotyped for C282Y and H63D mutations, and 2489 women also had their iron status assessed. Relations between serum ferritin and iron intake were investigated by using multiple linear regression, with adjustment for potential confounders. RESULTS: The strongest dietary association with serum ferritin concentration was a positive association with heme iron and not with nonheme or total iron. Weaker positive associations were seen with red and white meat, and negative associations were seen with total energy and white and brown whole-meal bread, independent of genotype and other potential confounders. The effect of genotype on ferritin concentrations primarily occurred after menopause, at which time a strong interaction between genotype and heme iron intake was observed. Other factors associated with serum ferritin concentrations were age, body mass index, blood donation, menopausal status, and HFE genotype. CONCLUSIONS: Postmenopausal women eating a diet rich in heme iron and who were C282Y homozygotes had the highest serum ferritin concentrations.

Do vitamin A serum levels moderate outcome or the protective effect of vitamin D on outcome from malignant melanoma?

BACKGROUND & AIMS: Low serum vitamin D levels (25-OH-vit D2/3) are reported to be associated with thicker melanomas and poorer outcome. Vitamin A metabolites and vitamin D bind to the same heterodimeric receptor. We report a study testing the hypothesis that high vitamin A levels may reduce the protective effect of vitamin D on outcome. METHODS: Serum vitamin A levels were measured in 795 melanoma cases and assessed for association with Breslow thickness, overall (OS) and melanoma-specific survival (MSS), and modification of the effect of vitamin D levels on survival. RESULTS: Higher vitamin A levels (≥ 2.2 µmol/l) conferred a non-significant increased risk of melanoma-specific death (adjusted HR = 1.11, 95%CI(0.74-1.67), p = 0.60) but not for death overall (adjusted HR = 0.95, 95%CI(0.65-1.39), p = 0.79). There was reduction in the protective effect of vitamin D on OS in patients with high vitamin A levels (≥ 2.2 µmol/l)(HR = 0.99, 95%CI(0.72-1.36),p = 0.93) compared to patients with low levels (<2.2 µmol)(HR = 0.77, 95%CI(0.64-0.93),p = 0.007), although the difference was not statistically significant (p = 0.26). CONCLUSIONS: High vitamin A levels may reduce the protective effect of vitamin D. As sub-optimal levels of vitamin D are common in temperate climates, and are usually managed by dietary supplementation, we suggest vitamin D3 supplementation alone might be preferable for melanoma patients than preparations containing vitamin D and A.

Inherited variants in the MC1R gene and survival from cutaneous melanoma: a BioGenoMEL study.

Inherited MC1R variants modulate MITF transcription factor signaling, which in turn affects tumor cell proliferation, apoptosis, and DNA repair. The aim of this BioGenoMEL collaborative study in 10 melanoma cohorts was to test the hypothesis that inherited variants thereby moderate survival expectation. A survival analysis in the largest cohort (Leeds) was carried out adjusting for factors known to impact on survival. The results were then compared with data from nine smaller cohorts. The absence of any consensus MC1R alleles was associated with a significantly lower risk of death in the Leeds set (HR, 0.64; 95% CI, 0.46-0.89) and overall in the 10 data sets (HR, 0.78; 95% CI, 0.65-0.94) with some support from the nine smaller data sets considered together (HR, 0.83; 95% CI, 0.67-1.04). The data are suggestive of a survival benefit for inherited MC1R variants in melanoma patients.

Relationship between sun exposure and melanoma risk for tumours in different body sites in a large case-control study in a temperate climate.

AIM: A melanoma case-control study was conducted to elucidate the complex relationship between sun exposure and risk. METHODS: Nine hundred and sixty population-ascertained cases, 513 population and 174 sibling controls recruited in England provided detailed sun exposure and phenotype data; a subset provided serum 25-hydroxyvitamin D(2)+D(3) levels. RESULTS: Phenotypes associated with a tendency to sunburn and reported sunburn at ≥ 20 years of age were associated with increased melanoma risk (odds ratio (OR) 1.56, 95% confidence intervals (CI) 1.23-1.99). Holiday sun exposure was not associated with an increased melanoma risk although this may be in part because reported sun exposure overall was much lower in those with a sun-sensitive phenotype, particularly among controls. Head and neck melanoma was associated with less sun exposure on holidays at low latitudes (OR 0.39, 95% CI (0.23-0.68) for >13 h/year compared to <3.1). Overall the clearest relationship between reported sun exposure and risk was for average weekend sun exposure in warmer months, which was protective (OR 0.67, 95% CI 0.50-0.89 for highest versus lowest tertile of exposure). Serum vitamin D levels were strongly associated with increased weekend and holiday sun exposure. CONCLUSIONS: Sun-sensitive phenotypes and reported sunburn were associated with an increased risk of melanoma. Although no evidence was seen of a causal relationship between holiday sun exposure and increased risk, this is consistent with the view that intense sun exposure is causal for melanoma in those prone to sunburn. A protective effect of regular weekend sun exposure was seen, particularly for limb tumours, which could be mediated by photoadaptation or higher vitamin D levels.

Serum 25-hydroxyvitamin D3 levels are associated with breslow thickness at presentation and survival from melanoma.

PURPOSE: A cohort study was carried out to test the hypothesis that higher vitamin D levels reduce the risk of relapse from melanoma. METHODS: A pilot retrospective study of 271 patients with melanoma suggested that vitamin D may protect against recurrence of melanoma. We tested these findings in a survival analysis in a cohort of 872 patients recruited to the Leeds Melanoma Cohort (median follow-up, 4.7 years). RESULTS: In the retrospective study, self-reports of taking vitamin D supplements were nonsignificantly correlated with a reduced risk of melanoma relapse (odds ratio = 0.6; 95% CI, 0.4 to 1.1; P = .09). Nonrelapsers had higher mean 25-hydroxyvitamin D(3) levels than relapsers (49 v 46 nmol/L; P = .3; not statistically significant). In the cohort (prospective) study, higher 25-hydroxyvitamin D(3) levels were associated with lower Breslow thickness at diagnosis (P = .002) and were independently protective of relapse and death: the hazard ratio for relapse-free survival (RFS) was 0.79 (95% CI, 0.64 to 0.96; P = .01) for a 20 nmol/L increase in serum level. There was evidence of interaction between the vitamin D receptor (VDR) BsmI genotype and serum 25-hydroxyvitamin D(3) levels on RFS. CONCLUSION: Results from the retrospective study were consistent with a role for vitamin D in melanoma outcome. The cohort study tests this hypothesis, providing evidence that higher 25-hydroxyvitamin D(3) levels, at diagnosis, are associated with both thinner tumors and better survival from melanoma, independent of Breslow thickness. Patients with melanoma, and those at high risk of melanoma, should seek to ensure vitamin D sufficiency. Additional studies are needed to establish optimal serum levels for patients with melanoma.

Vitamin D receptor gene polymorphisms, serum 25-hydroxyvitamin D levels, and melanoma: UK case-control comparisons and a meta-analysis of published VDR data.

We have carried out melanoma case-control comparisons for six vitamin D receptor (VDR) gene single nucleotide polymorphisms (SNPs) and serum 25-hydroxyvitamin D(3) levels in order to investigate the role of vitamin D in melanoma susceptibility. There was no significant evidence of an association between any VDR SNP and risk in 1028 population-ascertained cases and 402 controls from Leeds, UK. In a second Leeds case-control study (299 cases and 560 controls) the FokI T allele was associated with increased melanoma risk (odds ratio (OR) 1.42, 95% confidence interval (CI) 1.06-1.91, p=0.02). In a meta-analysis in conjunction with published data from other smaller data sets (total 3769 cases and 3636 controls), the FokI T allele was associated with increased melanoma risk (OR 1.19, 95% CI 1.05-1.35), and the BsmI A allele was associated with a reduced risk (OR 0.81, 95% CI 0.72-0.92), in each instance under a parsimonious dominant model. In the first Leeds case-control comparison cases were more likely to have a higher body mass index (BMI) than controls (p=0.007 for linear trend). There was no evidence of a case-control difference in serum 25-hydroxyvitamin D(3) levels. In 1043 incident cases from the first Leeds case-control study, a single estimation of serum 25-hydroxyvitamin D(3) level taken at recruitment was inversely correlated with Breslow thickness (p=0.03 for linear trend). These data provide evidence to support the view that vitamin D and VDR may have a small but potentially important role in melanoma susceptibility, and putatively a greater role in disease progression.