Vitamin D and overall mortality

Vitamin D, melanoma risk, and tumor thickness in PLCO cancer screening trial patients

OBJECTIVE

The incidence of melanoma is increasing. Other than limiting UV exposure, few factors prevent or reduce the risk of melanoma. The aim of this study is to evaluate the relationship between vitamin D intake and melanoma risk in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial.

METHODS

A secondary data analysis was performed on PLCO data. More than 1,300 participants developed melanoma.

RESULTS

Melanoma risk may be increased among men within the highest quartile of vitamin D intake (HR 1.27, 95% CI 0.99, 1.61). Women in the highest quartile of vitamin D intake had a decreased risk of invasive melanoma (HR 0.63, 95% CI 0.41, 0.96). Higher education and being white corresponded with deeper tumors (P < .001).

CONCLUSION

High reported vitamin D intake resulted in an increased risk of melanoma among men. Vitamin D intake yielded a protective effect against invasive melanoma in women.

25-Hydroxyvitamin D serum levels and melanoma risk: a case-control study and evidence synthesis of clinical epidemiological studies

There is accumulating evidence that the vitamin D pathway may play a role in melanoma. The aim of this study was to investigate the association between 25-hydroxyvitamin D [25(OH)D] serum levels and the risk of cutaneous melanoma. A case-control study with 137 incident cases of melanoma (serum samples collected at the time of diagnosis) and 99 healthy controls (serum samples collected between October and April) was carried out and evaluated in the framework of an evidence synthesis of clinical epidemiological studies on the topic to facilitate comparisons and summarize the scientific evidence produced so far. There was a statistically significant difference in the median levels of serum vitamin D between melanoma patients and healthy controls (18.0 vs. 27.8 ng/ml, P<0.001). Among melanoma patients, 66.2%, compared with 15.2% of healthy controls, had vitamin D deficiency (≤20 ng/ml), whereas vitamin D sufficiency (≥30 ng/ml) was observed in only 7.4% of melanoma patients and in 37.4% of the healthy controls (P<0.001). A multivariate model including age, sex, and BMI showed a statistically significant inverse association between melanoma and vitamin D sufficiency versus deficiency (odds ratio=0.04; 95% confidence interval: 0.02-0.10, P<0.001). Also, vitamin D insufficiency versus deficiency was significantly inversely associated with melanoma (odds ratio=0.13; 95% confidence interval: 0.06-0.27, P<0.001). These results suggest that both deficient and insufficient serum levels of vitamin D are associated with melanoma and that a trend seems to be present with a reduced risk of melanoma when vitamin D approaches normal values.

Overview on vitamin D and sunbed use

Vitamin D seems to be associated with a protective effect in a vast range of diseases, including cardiovascular, autoimmune and oncologic conditions. Since ultraviolet (UV) B light is the most important prerequisite for the cutaneous synthesis of vitamin D, sunbeds are able to increase serum vitamin D levels, although only transiently in most cases. In this scenario, the artificial tanning industry relentlessly tries to promote the use of sunbeds as a 'safe' therapeutic measure to achieve an adequate serum vitamin D status. The World Health Organization classified UV-emitting tanning devices, as well as the whole UV spectrum, as group-1 carcinogens, as they significantly increase the risk of melanoma and non-melanoma skin cancer. In case of vitamin D deficiency or insufficiency, the current risk-benefit ratio is therefore in favour of vitamin D supplementation instead of sunbed use. Artificial tanning devices should never be considered as an option to achieve an appropriate vitamin D status. Their supposedly beneficial effects, vastly publicised by the artificial tanning industry, are not worth the carcinogenic risk associated with sunbed use.

Vitamin D status and risk for malignant cutaneous melanoma: recent advances

Cutaneous malignant melanoma, whose incidence is increasing steadily worldwide, is the result of complex interactions between individual genetic factors and environmental risk factors. Ultraviolet radiation represents the most important environmental risk factor for the development of skin cancers, including melanoma. Sun exposure and early sunburn during childhood are the principal causes of cutaneous melanoma insurgence in adults, with double the risk relative to a nonexposed population. Consequently, ultraviolet protection has long been recognized as an important measure to prevent such a malignancy. Biological and epidemiological data suggest that vitamin D status could affect the risk of cancer and play a role in cancer prevention by exerting antiproliferative effects. Solar radiations are critical for vitamin D synthesis in humans; however, uncontrolled and intensive sun exposure is dangerous to skin health and may contribute toward the development of cutaneous malignant melanoma. An optimum balance between sun protection and exposure is thus advocated. Additional research is required to confirm the preventive role of vitamin D in melanoma incidence or a positive influence on patient outcome.

Sun exposure and melanoma prognostic factors

Previous studies have reported an association between sun exposure and the increased survival of patients with cutaneous melanoma (CM). The present study analyzed the association between ultraviolet (UV) light exposure and various prognostic factors in the Italian Clinical National Melanoma Registry. Clinical and sociodemographic features were collected, as well as information concerning sunbed exposure and holidays with sun exposure. Analyses were performed to investigate the association between exposure to UV and melanoma prognostic factors. Between December 2010 and December 2013, information was obtained on 2,738 melanoma patients from 38 geographically representative Italian sites. A total of 49% of the patients were >55 years old, 51% were men, 50% lived in the north of Italy and 57% possessed a high level of education (at least high school). A total of 8 patients had a family history of melanoma and 56% had a fair phenotype (Fitzpatrick skin type I or II). Of the total patients, 29% had been diagnosed with melanoma by a dermatologist; 29% of patients presented with a very thick melanoma (Breslow thickness, >2 mm) and 25% with an ulcerated melanoma. In total, 1% of patients had distant metastases and 13% exhibited lymph node involvement. Holidays with sun exposure 5 years prior to CM diagnosis were significantly associated with positive prognostic factors, including lower Breslow thickness (P<0.001) and absence of ulceration (P=0.009), following multiple adjustments for factors such as sociodemographic status, speciality of doctor performing the diagnosis and season of diagnosis. Sunbed exposure and sun exposure during peak hours of sunlight were not significantly associated with Breslow thickness and ulceration. Holidays with sun exposure were associated with favorable CM prognostic factors, whereas no association was identified between sunbed use and sun exposure during peak hours of sunlight with favorable CM prognostic factors. However, the results of the present study do not prove a direct causal effect of sun exposure on melanoma prognosis, as additional confounding factors, including vitamin D serum levels, may have a role.

Publication bias in dermatology systematic reviews and meta-analyses

Systematic reviews and meta-analyses in dermatology provide high-level evidence for clinicians and policy makers that influence clinical decision making and treatment guidelines. One methodological problem with systematic reviews is the under representation of unpublished studies. This problem is due in part to publication bias. Omission of statistically non-significant data from meta-analyses may result in overestimation of treatment effect sizes which may lead to clinical consequences. Our goal was to assess whether systematic reviewers in dermatology evaluate and report publication bias. Further, we wanted to conduct our own evaluation of publication bias on meta-analyses that failed to do so. Our study considered systematic reviews and meta-analyses from ten dermatology journals from 2006 to 2016. A PubMed search was conducted, and all full-text articles that met our inclusion criteria were retrieved and coded by the primary author. 293 articles were included in our analysis. Additionally, we formally evaluated publication bias in meta-analyses that failed to do so using trim and fill and cumulative meta-analysis by precision methods. Publication bias was mentioned in 107 articles (36.5%) and was formally evaluated in 64 articles (21.8%). Visual inspection of a funnel plot was the most common method of evaluating publication bias. Publication bias was present in 45 articles (15.3%), not present in 57 articles (19.5%) and not determined in 191 articles (65.2%). Using the trim and fill method, 7 meta-analyses (33.33%) showed evidence of publication bias. Although the trim and fill method only found evidence of publication bias in 7 meta-analyses, the cumulative meta-analysis by precision method found evidence of publication bias in 15 meta-analyses (71.4%). Many of the reviews in our study did not mention or evaluate publication bias. Further, of the 42 articles that stated following PRISMA reporting guidelines, 19 (45.2%) evaluated for publication bias. In comparison to other studies, we found that systematic reviews in dermatology were less likely to evaluate for publication bias. Evaluating and reporting the likelihood of publication bias should be standard practice in systematic reviews when appropriate.

Meta-analysis of vitamin D-binding protein and cancer risk

BACKGROUND

Epidemiologic evidence supported a role for vitamin D and vitamin D receptor (VDR) polymorphisms in cancer risk. Beyond VDR, the biologic effects of vitamin D are mediated by the vitamin D-binding protein (DBP), a key protein in vitamin D metabolism. Furthermore, the gene encoding the DBP (GC, group-specific component) has an important role in the vitamin D pathway. Several studies investigated DBP serologic levels and GC polymorphisms in association with cancer risk with controversial results. Thus, we carried out a meta-analysis to investigate these associations.

METHODS

We included 28 independent studies concerning the following tumors: basal cell carcinoma, bladder, breast, colon-rectum, endometrium, liver, esophagus, stomach, melanoma, pancreas, prostate, and kidney. Through random-effect models, we calculated the summary odds ratios (SOR) for serum DBP and the GC polymorphisms rs2282679, rs12512631, rs7041, rs4588, rs17467825, rs1155563, and rs1352844.

RESULTS

We found a borderline decrease in cancer risk for subjects with high compared with low levels of DBP [SOR, 0.75; 95% confidence interval (CI), 0.56-1.00]. Dose-response meta-analysis indicates a nonsignificant decrease risk for an increase of 1,000 nmol/L of DBP (SOR, 0.96; 95% CI, 0.91-1.01). We found no significant alterations in cancer risk for subjects carrying any of the studied GC polymorphisms compared with wild-type subjects both in the main analysis and in analyses stratified by cancer type and ethnicity.

CONCLUSIONS

We found trends toward significance, suggesting a role of DBP in cancer etiology, which should be confirmed in further studies.

IMPACT

To our knowledge, this is the first study to investigate GC polymorphisms and DBP serologic levels in association with any type of cancer.

The Inverse Relationship between 25-Hydroxyvitamin D and Cancer Survival: Discussion of Causation

Cancer mortality rates vary inversely with geographic latitude and solar ultraviolet-B doses. This relationship may be due to an inhibitory role of vitamin D on cancer development. The relationship between vitamin D and cancer appears to be stronger for studies of cancer mortality than incidence. Because cancer mortality reflects both cancer incidence and survival, the difference may be due to effects of vitamin D on cancer survival. Here we review analytic epidemiologic studies investigating the relation between vitamin D, measured by circulating levels of 25-hydroxyvitamin D (25-OHD), and cancer survival. A relationship between low 25-OHD levels and poor survival is shown by most of the reviewed studies. This relationship is likely to be causal when viewed in light of most criteria for assessing causality (temporality, strength, exposure-response, biological plausibility and consistency). A serum level of 25-OHD around 50 nmol/L appears to be a threshold level. Conversely, there are several mechanisms whereby cancer could lower serum levels of 25-OHD. The severity of disease at the time of diagnosis and time of serum sampling are key factors to clarify the temporal aspect of these relationships. Evidence that vitamin D supplementation could retard the disease process or prolong survival time would be key evidence, but is difficult to generate. However, recent clinical trial results in prostate cancer support a role for vitamin D in this regard.

Sunny holidays before and after melanoma diagnosis are respectively associated with lower Breslow thickness and lower relapse rates in Italy

Background

Previous studies have reported an association between sun exposure and improved cutaneous melanoma (CM) survival. We analysed the association of UV exposure with prognostic factors and outcome in a large melanoma cohort.

Methods

A questionnaire was given to 289 (42%) CM patients at diagnosis (Group 1) and to 402 CM patients (58%) during follow-up (Group 2). Analyses were carried out to investigate the associations between sun exposure and melanoma prognostic factors and survival.

Results

Holidays in the sun two years before CM diagnosis were significantly associated with lower Breslow thickness (p=0.003), after multiple adjustment. Number of weeks of sunny holidays was also significantly and inversely associated with thickness in a dose-dependent manner (p=0.007). However when stratifying by gender this association was found only among women (p=0.0004) the risk of CM recurrence in both sexes was significantly lower in patients (n=271) who had holidays in the sun after diagnosis, after multiple adjustment including education: HR=0.30 (95%CI:0.10-0.87; p=0.03) conclusions: Holidays in the sun were associated with thinner melanomas in women and reduced rates of relapse in both sexes. However, these results do not prove a direct causal effect of sun exposure on survival since other confounding factors, such as vitamin D serum levels and socio-economic status, may play a role. Other factors in sun seeking individuals may also possibly affect these results.

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

BACKGROUND

Serum 25-hydroxyvitamin D3 (Vitamin D) insufficiency and single-nucleotide polymorphisms (SNPs) on its receptor, Vitamin D receptor (VDR), have been reported to be involved in melanoma susceptibility in populations mostly from northern countries.

OBJECTIVE

To investigate 25-hydroxyvitamin D3 levels and VDR SNPs in melanoma patients from sunny area of Barcelona, two studies were carried out. The first study evaluated the levels of Vitamin D at time of melanoma diagnosis and the second one analyzed the association between VDR genetic variants and risk of having a high nevus number, the strongest phenotypic risk factor for melanoma.

METHODS

The levels of 25-hydroxyvitamin D3 in 81 melanoma patients at diagnosis were measured. In a second group of melanoma patients, including 150 with low and 113 with high nevus number, 11 VDR SNPs were analyzed for their association with nevus number.

RESULTS

In the first study, 68% of patients had insufficient levels of 25-hydroxyvitamin D3 (<25 ng/ml). Autumn-winter months and fair phototype were associated with 25-hydroxyvitamin D3 insufficiency; after multivariate analysis, season of sampling remained the only independent predictor of 25-hydroxyvitamin D3 levels. In the second study, VDR variant rs2189480 (P = 0.006) was associated with risk of high nevus number whereas rs2239179 (P = 0.044) and rs7975128 (P = 0.0005) were protective against high nevus number. After Bonferroni adjustment only rs7975128 remained significant. In stratified analysis, SNP rs7975128 was found protective against multiple melanomas (P = 0.021).

CONCLUSION

This study showed that even in Barcelona, a sunny Mediterranean area, 25-hydroxyvitamin D3 levels were sub-optimal in the majority of melanoma patients at diagnosis. The involvement of VDR in nevi and, in turn, in melanoma susceptibility has also been suggested. Larger studies are needed to confirm our findings.