An ecologic study of cancer mortality rates in Spain with respect to indices of solar UVB irradiance and smoking

An estimate of the global reduction in mortality rates through doubling vitamin D levels

BACKGROUND/OBJECTIVES

The goal of this work is to estimate the reduction in mortality rates for six geopolitical regions of the world under the assumption that serum 25-hydroxyvitamin D (25(OH)D) levels increase from 54 to 110 nmol/l.

SUBJECTS/METHODS

This study is based on interpretation of the journal literature relating to the effects of solar ultraviolet-B (UVB) and vitamin D in reducing the risk of disease and estimates of the serum 25(OH)D level-disease risk relations for cancer, cardiovascular disease (CVD) and respiratory infections. The vitamin D-sensitive diseases that account for more than half of global mortality rates are CVD, cancer, respiratory infections, respiratory diseases, tuberculosis and diabetes mellitus. Additional vitamin D-sensitive diseases and conditions that account for 2 to 3% of global mortality rates are Alzheimer's disease, falls, meningitis, Parkinson's disease, maternal sepsis, maternal hypertension (pre-eclampsia) and multiple sclerosis. Increasing serum 25(OH)D levels from 54 to 110 nmol/l would reduce the vitamin D-sensitive disease mortality rate by an estimated 20%.

RESULTS

The reduction in all-cause mortality rates range from 7.6% for African females to 17.3% for European females. Reductions for males average 0.6% lower than for females. The estimated increase in life expectancy is 2 years for all six regions.

CONCLUSIONS

Increasing serum 25(OH)D levels is the most cost-effective way to reduce global mortality rates, as the cost of vitamin D is very low and there are few adverse effects from oral intake and/or frequent moderate UVB irradiance with sufficient body surface area exposed.

Effect of interval between serum draw and follow-up period on relative risk of cancer incidence with respect to 25-hydroxyvitamin D level: Implications for meta-analyses and setting vitamin D guidelines

Ecological studies have reported strong inverse correlations between indices of solar ultraviolet-B (UVB) doses and incidence and/or mortality rates for many types of cancer. Case-control studies (CCS) generally find inverse correlations between serum 25-hydroxyvitamin D [25(OH)D] concentration measured at time of diagnosis for cancer incidence, whereas nested case-control studies (NCCS), which involve a several-year follow-up time after serum sampling, generally do not. This paper examines the relation between follow-up interval and relative risk (RR) for breast, colorectal, and prostate cancer. I plot the RR versus serum 25(OH)D data as a function of follow-up time from the literature for each type of cancer. For breast cancer, RRs were significantly reduced only for follow-up periods less than 3 years. For colorectal cancer, RRs were generally significantly reduced for follow-up periods up to 12 years. For prostate cancer, RRs were not statistically significant from 4 years to 28 years. This study included no CCS. Follow-up periods after serum sampling should not be too long for breast cancer because once a tumor reaches a diameter of 1-3 mm, it requires angiogenesis to continue growing, and vitamin D reduces angiogenesis around tumors. Breast cancer diagnoses are more common in spring and fall than in summer or winter, indicating that they can grow rapidly if circulating 25(OH)D drops in the fall or melatonin levels drop in spring. Serum sampling should be conducted during the study, perhaps every 2 years, to overcome the problem of change of 25(OH)D concentration during cohort studies.

Serum 25-hydroxyvitamin D and risk of oropharynx and larynx cancers in Finnish men

BACKGROUND

Published studies suggesting a relationship between vitamin D and some common cancers sparked interest in the association of vitamin D with head and neck cancers. Prolonged darker months in Finland are associated with lower levels of ultraviolet B radiation, raising concerns about low vitamin D levels.

METHODS

We used a nested case--control study in the prospective Alpha-Tocopherol Beta Carotene (ATBC) Study of male smokers in Finland, to examine the relationship between serum 25(OH)D and risk of developing squamous cancers of the head and neck. Using conditional logistic regression, we calculated the multivariate adjusted ORs and CIs comparing those with serum 25(OH)D adequate levels of 50 to <75 nmol/L to those <25.0.

RESULTS

We identified incident cancers of the oral cavity (n = 134), pharynx (n = 48), and larynx (n = 158). Median serum vitamin D was 31 nmol/L (interquartile range: 21-48), which is below the 50 nmol/L cutoff point was considered adequate for bone and overall health. Comparing those with serum 25(OH)D below 25 nmol/L to those 50 to <75 nmol/L as the referent, the OR was 1.35 (95% CI: 0.53-3.43, P(trend) = 0.65) for overall head and neck cancers. Stratification by cancer subsites of the oral cavity, pharynx, and larynx (P(trend) = 0.93, 0.78, 0.26, respectively) or by season of blood draw also showed no association.

CONCLUSIONS

Our study showed no association between serum 25(OH)D and risk of head and neck cancers.

IMPACT

This study does not support the hypothesis that greater vitamin D exposure would reduce the risk of developing head and neck squamous cancers.

Prospective study of UV exposure and cancer incidence among Swedish women

BACKGROUND

Except for skin melanoma and nonmelanoma skin cancer, little evidence from prospective studies is available on the association between UV exposure and cancer risk.

METHODS

We followed prospectively 49,261 women aged 30 to 49 years at enrollment in 1991 to 1992 for 15 years. Cancer incidence was analyzed by fitting Cox models, and estimating hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

2,303 incident cases of cancer were diagnosed (breast: 1,053, ovary: 126, lung: 116, colon-rectum: 133, and brain: 116). No associations were found between any cumulative measure of UV exposure at ages 10 to 39 years and overall cancer risk. However, spending ≥1 week/year between ages 10 and 29 years on sunbathing vacations led to an inverse association with overall cancer risk (HR: 0.70, 95% CI: 0.53-0.93) and breast cancer risk (HR: 0.56, 95% CI: 0.36-0.89) when compared with women who never went on such vacations. Solarium use was inversely associated with breast cancer risk, whereas ≥2 sunburns/year was inversely associated with lung cancer risk. No other associations were found between sun exposure or solarium use at ages 10 to 39 years and cancer risk.

CONCLUSION

We found no evidence of an association between any cumulative measure of UV exposure at ages 10 to 39 years and overall cancer risk. UV exposure earlier in life was related to reduced overall and breast cancer risk.

IMPACT

Further research is needed to define the amount of solar or artificial UV exposure that may, or may not, be beneficial for cancer prevention.

Requirements for Vitamin D Across the Life Span

Adequate provision of vitamin D has been found, in ecological, cross-sectional, and observational studies, to be associated with reduction in the risk of many types of cancer, cardiovascular diseases (CVDs), autoimmune diseases, diabetes mellitus types 1 and 2, neurological disorders, several bacterial and viral infections, and adverse pregnancy outcomes in addition to the classical bone disorders of rickets and osteomalacia. Furthermore, investigators have found adequate repletion and increased intakes of vitamin D to be associated with reduced all-cause mortality rates. These findings have been supported by the limited number of properly conducted randomized controlled trials (RCTs) that used more than 400 IU/day of vitamin D. This review presents an overview of the role of vitamin D for the promotion of health for the more important vitamin D-related diseases and conditions. Serum 25-hydroxyvitamin D concentrations of 30—60 ng/ml, corresponding to oral intake or skin production of 1,000—4,000 IU/day of vitamin D, appear necessary in adults for avoidance of hypovitaminosis D-related ill health. People of all ages are encouraged to obtain more vitamin D from judicious exposure to sunshine (for ultraviolet B [UVB] irradiation) or from regular vitamin D supplements because dietary sources do not provide sufficient vitamin D to prevent any health risks other than those of rickets and osteomalacia.

Possible role of serum 25-hydroxyvitamin D in black-white health disparities in the United States

Significant health disparities exist between African Americans (AAs) and White Americans (WAs). The all-cause mortality rate for AAs in 2006 was 26% higher than for non-Hispanic WAs. Explanations for the disparities usually include socioeconomic status, lifestyle behaviors, social environment, and access to preventive health care services. However, several studies indicate that these factors do not account for the observed disparities. Many studies report that vitamin D has important health benefits through paracrine and autocrine mechanisms and that higher serum 25-hydroxyvitamin D (25[OH]D) levels are associated with better health outcomes. AAs have a population mean serum 25(OH)D level of 16 ng/mL, whereas WAs have a level of 26 ng/mL. From preliminary meta-analyses of serum 25(OH)D level-disease outcome from observational studies, differences in serum 25(OH)D level for AAs and WAs can explain many of the health disparities. The ratios of mortality rates for AAs to WAs for female breast cancer, colorectal cancer, cardiovascular disease, and all-cause mortality rate in 2006 were 1.34, 1.43, 1.29, and 1.26, respectively. The 25(OH)D level-disease outcome ratios for 16 ng/mL versus 26 ng/mL for the same diseases were 1.26, 1.44, 1.27, and 1.26, respectively. The close agreement between these 2 sets of numbers suggests that low serum 25(OH)D level is an important health risk for AAs. Given the widespread vitamin D deficiency in the AA population and the potential widespread health benefits that accompany adequate replacement, we believe that addressing this issue may be the single most important public health measure that can be undertaken.

Ultraviolet exposure and mortality among women in Sweden

BACKGROUND

Ecological studies have reported possible effects of sunlight on the risk of several diseases. Little evidence is available on the association between mortality and solar and artificial UV exposure by individual level from prospective studies.

METHODS

The Swedish Women's Lifestyle and Health cohort study included women aged 30 to 49 years in 1991-1992. Participants completed a questionnaire and were followed-up through linkages to national registries until the end of 2006. Cox models were used to estimate adjusted HRs and 95% CIs for all-cause mortality and for cancer and cardiovascular disease (CVD) mortality.

RESULTS

During 15 years of follow-up, among the 38,472 women included in the present study, 754 deaths occurred: 457 due to cancer and 100 due to CVD. When combining the information on sun exposure from age 10 to 39 years, women who got sunburned twice or more per year during adolescence had a reduced all-cause mortality, compared with women who had been sunburned once or less. A reduced risk for all-cause and CVD mortality was observed in women who went on sunbathing vacations more than once a year over three decades. Solarium use once or more per month for at least one decade increased the risk of all-cause mortality, when compared with women who never used a solarium.

CONCLUSIONS

Solar UV exposure was associated with reduced overall and CVD mortality, whereas artificial UV exposure was associated with increased overall and cancer mortality among Swedish women.

IMPACT

Moderate sun exposure may protect against cause-specific mortality.

Role of vitamin d in the prevention of pancreatic cancer

Pancreatic cancer is a malignancy of poor prognosis which is mostly diagnosed at advanced stages. Current treatment modalities are very limited creating great interest for novel preventive and therapeutic options. Vitamin D seems to have a protective effect against pancreatic cancer by participating in numerous proapoptotic, antiangiogenic, anti-inflammatory, prodifferentiating, and immunomodulating mechanisms. 25-hydroxyvitamin D [25(OH)D] serum concentrations are currently the best indicator of vitamin D status. There are three main sources of vitamin D: sun exposure, diet,and dietary supplements. Sun exposure has been associated with lower incidence of pancreatic cancer in ecological studies. Increased vitamin D levels seem to protect against pancreatic cancer, but caution is needed as excessive dietary intake may have opposite results. Future studies will verify the role of vitamin D in the prevention and therapy of pancreatic cancer and will lead to guidelines on adequate sun exposure and vitamin D dietary intake.

Vitamin d and pancreatic cancer-an update

The non-classical actions of vitamin D, namely anti-proliferation, pro-differentiation, immune function modulation, and anti-inflammation, have received great attention during the past decade, in particular, the potential of vitamin D analogs alone or in combination with other anticancer agents for the treatment of a variety of cancers. The association between vitamin D status and the higher incidence of many forms of cancer has suggested that vitamin D may play a role in the etiology of these types of cancer. Although it is still controversial whether this association exists for pancreatic cancer, biochemical evidence clearly indicates pancreatic cancer cells are responsive to the inhibitory effect of vitamin D and its analogs. In this review, we discuss briefly the origin and current therapy of pancreatic cancer, the history, source, metabolism and functions of vitamin D, the recent progress in the epidemiological studies of sunlight, and vitamin D status, and biochemical studies of vitamin D analogs in the prevention and treatment of pancreatic cancer.

Rediscovering vitamin D

Over the past 2 years there has been a radical change in standard clinical practice with respect to vitamin D. As a result of a growing body of knowledgeable physicians are assessing the vitamin D nutritional status of their patients and prescribing aggressive repletion regimens of a vitamin D supplement. The present paper summarizes some basic information about this essential nutrient and reviews some of the more recent data implicating vitamin D deficiency in disease etiology with an emphasis on cardiovascular disease and cancer. Finally a rational approach to the dosing of vitamin D in different patient populations is provided.

Prevention of colorectal cancer with vitamin D

The fact that colorectal cancer (CRC) is the second leading cause of cancer mortality in the United States emphasizes the need for more effective preventive and therapeutic modalities. There is growing evidence that vitamin D may reduce the incidence of CRC. Results of epidemiologic, in vitro, in vivo animal and clinical studies suggest that a low serum vitamin D level may be a serious risk factor for CRC and a high serum vitamin D level may reduce the risk of CRC. On a molecular level, vitamin D suppresses CRC development and growth by affecting cell proliferation, differentiation, apoptosis, and angiogenesis. Vitamin D insufficiency and CRC are common in the elderly population. Vitamin D insufficiency is simple to screen for and treatable with vitamin D supplementation. Serum 25-hydroxyvitamin D (calcidiol) is the best measure of vitamin D status and should be checked routinely for individuals with risk factors for CRC. Maintaining serum concentrations of calcidiol above 32 ng/ml (80 nmol/l) in individuals whose serum calcidiol level is low may help prevent CRC as well as osteoporosis, fractures, infections, and cardiovascular disease. Daily calcidiol intake of 1000 International Units can increase serum vitamin D to sufficient levels in most elderly persons and, based on available data, may substantially lower the incidence of CRC with minimal risks.

A systematic literature review of vitamin D and ovarian cancer

OBJECTIVE

We assessed the evidence supporting a reduction in risk for ovarian cancer occurrence or mortality with greater vitamin D exposures.

STUDY DESIGN

This review followed standard guidelines for systematic literature reviews. The diverse study designs precluded a quantitative metaanalysis. Therefore studies are summarized via tables and abstracted information.

RESULTS

Approximately half of the ecologic and case-control studies reported reductions in incidence or mortality with increasing geographic latitude, solar radiation levels, or dietary/supplement consumption of vitamin D, whereas the other half reported null associations. The cohort studies reported no overall risk reduction with increasing dietary/supplement consumption of vitamin D or with plasma levels of vitamin D prior to diagnosis, although vitamin D intakes were relatively low in all studies.

CONCLUSION

There is no consistent or strong evidence to support the claim made in numerous review articles that vitamin D exposures reduce the risk for ovarian cancer occurrence or mortality.

Circulating 25-hydroxyvitamin D and risk of pancreatic cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers

Results from epidemiologic studies examining pancreatic cancer risk and vitamin D intake or 25-hydroxyvitamin D (25(OH)D) concentrations (the best indicator of vitamin D derived from diet and sun) have been inconsistent. Therefore, the authors conducted a pooled nested case-control study of participants from 8 cohorts within the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers (VDPP) (1974-2006) to evaluate whether prediagnostic circulating 25(OH)D concentrations were associated with the development of pancreatic cancer. In total, 952 incident pancreatic adenocarcinoma cases occurred among participants (median follow-up, 6.5 years). Controls (n = 1,333) were matched to each case by cohort, age, sex, race/ethnicity, date of blood draw, and follow-up time. Conditional logistic regression analysis was used to calculate smoking-, body mass index-, and diabetes-adjusted odds ratios and 95% confidence intervals for pancreatic cancer. Clinically relevant 25(OH)D cutpoints were compared with a referent category of 50-<75 nmol/L. No significant associations were observed for participants with lower 25(OH)D status. However, a high 25(OH)D concentration (> or =100 nmol/L) was associated with a statistically significant 2-fold increase in pancreatic cancer risk overall (odds ratio = 2.12, 95% confidence interval: 1.23, 3.64). Given this result, recommendations to increase vitamin D concentrations in healthy persons for the prevention of cancer should be carefully considered.

Ultraviolet B irradiance and vitamin D status are inversely associated with incidence rates of pancreatic cancer worldwide

OBJECTIVES

To determine if an inverse association exits between latitude, ultraviolet B (UVB) irradiance and incidence rates of pancreatic cancer worldwide.

METHODS

Multiple linear regression was used to investigate the relationship and between UVB irradiance incidence rates of pancreatic cancer and while controlling for cigarette, alcohol and sugar consumption, and proportion overweight. Serum 25-hydroxyvitamin D [25(OH)D] levels were estimated, and their association with incidence rates also was analyzed.

RESULTS

Incidence rates were higher at higher latitudes (R2 for latitude for men, 0.51; P < 0.001; R2 for latitude for women, 0.32; P < 0.001). Ultraviolet B irradiance also was independently inversely associated with incidence in men (P < 0.01) and women (P = 0.02). Alcohol (P < 0.0001) and cigarette (P < or = 0.01) consumption were positively associated with incidence in men (R2 for overall model for men, 0.76; P < 0.0001). Alcohol (P < 0.0001) and sugar (P = 0.001) consumption were positively associated with incidence rates in women (R2 for overall model for women, 0.64; P < 0.0001). Incidence rates were half as high in countries with estimated serum 25(OH)D >30 ng/mL (75 nmol/L) than in those with < or =30 ng/mL.

CONCLUSIONS

Countries with lower UVB irradiance had higher incidence rates of pancreatic cancer in both hemispheres, with occasional exceptions.

Independent and joint effects of serum 25-hydroxyvitamin D and calcium on ovarian cancer risk: a prospective nested case-control study

INTRODUCTION

Ovarian cancer has very few known modifiable risk factors but dietary studies suggest a role for vitamin D and calcium in the prevention of ovarian cancer. Thus, we investigated the association between pre-diagnostic serum calcium and 25-hydroxyvitamin D (25-OHD) on the risk of later development of ovarian cancer.

METHODS

We conducted a population-based nested case-control study within the Finnish Maternity Cohort (FMC). The cohort subset comprised 172 ovarian cancer cases with 172 matched controls (age ± 1 year, parity and season of blood donation ± 2 weeks).

RESULTS

We observed a significant inverse association between calcium and ovarian cancer risk. Relative risk (estimated as odds ratio, OR) comparing the highest quartile to the lowest quartile was significantly decreased; 0.41 [95% confidence interval (CI) 0.19-0.85, P-trend 0.004]. Even though a comparable association between 25-OHD and ovarian cancer did not reach statistical significance (OR 0.57, 95% CI 0.26-1.24, P-trend 0.07), having sufficient (> 75 nmol/L) serum 25-OHD levels compared to insufficient serum 25-OHD was associated with a significantly decreased risk of ovarian cancer (OR 0.32; 95% CI 0.12-0.91, p-value 0.03). No synergistic protective interaction between high levels of calcium and 25-OHD against ovarian cancer was observed, the joint effect being just multiplicative.

CONCLUSION

Calcium and vitamin D act independently to reduce the risk of ovarian cancer. The decreased risk of ovarian cancer associated with pre-diagnostic serum calcium and vitamin D needs to be evaluated further for possible new insights into ovarian cancer prevention.

Relation between prediagnostic serum 25-hydroxyvitamin D level and incidence of breast, colorectal, and other cancers

The evidence is increasing that higher serum 25-hydroxyvitamin D [25(OH)D] levels reduce the risk of many types of cancer. Ecological and observational studies yield the strongest evidence, with support from studies of mechanisms. A key question is identifying the relation between serum 25(OH)D level and cancer incidence. Meta-analyses of such studies is a reasonable approach to determine the serum 25(OH)D level-cancer incidence relation. This paper reports new meta-analyses for breast and colorectal cancers. Currently, the journal literature offers seven prospective breast cancer and ten prospective colorectal cancer studies that can be used. The data for these studies graphed and compared. Data from some of the studies were multiplied by factors to bring all the studies into reasonable agreement with a tentative dose-response relation. The data were fit with a variety of functions; the best fits were nonlinear functions that tended to asymptotically reach a lower odds ratio at higher serum 25(OH)D levels. These analyses estimated that the 50% reduction in incidence occurs for a value of 78 nmol/L compared with the value at 24 nmol/L for breast cancer, and a value of 60 nmol/L compared with the value at 15 nmol/L for colorectal cancer. Although these results are reasonable, some concern exists that a single serum 25(OH)D level, measured years prior to diagnosis of cancer, does not adequately represent the serum levels for the entire period before diagnosis. Future prospective studies should include more serum 25(OH)D level measurements during the study course.

Predicted vitamin D status and pancreatic cancer risk in two prospective cohort studies

Background:

Studies evaluating vitamin D status in relation to pancreatic cancer risk have yielded inconsistent results.

Methods:

We prospectively followed 118 597 participants in the Nurses' Health Study and Health Professionals Follow-up Study from 1986 to 2006. We calculated a 25-hydroxyvitamin D (25(OH)D) score from known predictors of vitamin D status for each individual and then examined the predicted 25(OH)D levels in relation to pancreatic cancer risk. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models adjusted for age, sex, race, height, smoking, and diabetes. We then further adjusted for body mass index (BMI) and physical activity in a sensitivity analysis.

Results:

During 20 years of follow-up, we identified 575 incident pancreatic cancer cases. Higher 25(OH)D score was associated with a significant reduction in pancreatic cancer risk; compared with the lowest quintile, participants in the highest quintile of 25(OH)D score had an adjusted RR of 0.65 (95% CI=0.50–0.86; P_trend=0.001). Results were similar when we further adjusted for BMI and physical activity.

Conclusions:

Higher 25(OH)D score was associated with a lower risk of pancreatic cancer in these two prospective cohort studies.

Dr. Frank caldwell garland, june 20, 1950-august 17, 2010

Frank Caldwell Garland, Ph.D., died August 17, 2010 after a year-long battle with cancer. He will be remembered for his seminal work with his brother Cedric F. Garland in proposing the ultraviolet-B (UVB)-vitamin D-cancer hypothesis to explain the geographical variation of colon cancer mortality rates in the United States in 1980. This hypothesis has been extended to about 20 types of cancer using the ecological approach, and supported strongly by observational studies of prediagnostic serum 25-hydroxyvitamin D [25(OH) D] for incidence of breast, colorectal and ovarian cancer, and a randomized controlled trial that used sufficient vitamin D (1,150 IU/day) to and found a strongly beneficial effect on cancer incidence. The UVB-vitamin D-cancer hypothesis is also supported by studies that used as the index of solar UVB irradiance the amount of sunlight exposure in childhood or incidence of non-melanoma skin cancer. Survival after diagnosis was increased for individuals with higher serum 25(OH)D levels at the time of cancer diagnosis for six types of cancer: breast, colorectal, lung and prostate cancer; melanoma and non-Hodgkin's lymphoma. The ecological study approach is ideally suited to studying cancer risk-modifying factors since the lag between cancer initiation and detection or death can be 20-40 years or more, making ordinary observational studies difficult. The impact on vitamin D research by both Frank Garland and Cedric Garland has been immense. Health policy leaders will realize this in the near future, providing a rich legacy for humanity.

An ecological study of cancer incidence and mortality rates in France with respect to latitude, an index for vitamin D production

France has unexplained large latitudinal variations in cancer incidence and mortality rates. Studies of cancer rate variations in several other countries, as well as in multicountry studies, have explained such variations primarily in terms of gradients in solar ultraviolet-B (UVB) doses and vitamin D production. To investigate this possibility in France, I obtained data on cancer incidence and mortality rates for 21 continental regions and used this information in regression analyses with respect to latitude. This study also used dietary data. Significant positive correlations with latitude emerged for breast, colorectal, esophageal (males), lung (males), prostate, both uterine cervix and uterine corpus, all and all less lung cancer. Although correlations with latitude were similar for males and females, the regression variance for all and all less lung cancer was about twice as high for males than for females. Lung cancer incidence and mortality rates for females had little latitudinal gradient, indicating that smoking may have also contributed to the latitudinal gradients for males. On the basis of the available dietary factor, micro- and macronutrient data, dietary differences do not significantly affect geographical variation in cancer rates. These results are consistent with solar UVB's reducing the risk of cancer through production of vitamin D. In the context of serum 25-hydroxyvitamin D level-cancer incidence relations, cancer rates could be reduced significantly in France if everyone obtained an additional 1,000 IU/day of vitamin D. Many other benefits of vitamin D exist as well.

An ecological study of cancer mortality rates in the United States with respect to solar ultraviolet-B doses, smoking, alcohol consumption and urban/rural residence

The Cohort Consortium Vitamin D Polling Project of Rarer Cancers (VDPP ) study failed to find a beneficial role of prediagnostic serum 25-hydroxyvitamin D [25(OH)D] levels on risk of seven types of rarer cancer: endometrial, esophageal, gastric, kidney, ovarian and pancreatic cancer and non-Hodgkin's lymphoma (NHL). However, ecological studies and studies of oral vitamin D intake have generally found solar ultraviolet B (UVB) and oral vitamin D inversely correlated with incidence and/or mortality rates of these cancers. To explore the discrepancy, I conducted an ecological study of cancer mortality rates for white Americans in the United States for 1950-1994 with data for 503 state economic areas in multiple linear regression analyses with respect to UVB for July, lung cancer, alcohol consumption and urban/rural residence. UVB was significantly inversely correlated with six types of cancer (not pancreatic cancer) in both periods. However, the adjusted R(2) values were much lower for cancers with lower mortality rates than those in an earlier ecological study that used state-averaged data. This finding suggests that the VDPP study may have had too few cases. Thus, the VDPP study should not be considered as providing strong evidence against the solar UVB-vitamin D-cancer hypothesis.

Meta-analysis of longitudinal studies: Serum vitamin D and prostate cancer risk

AIM

To review and summarize evidence from longitudinal studies on the association between serum 25-hydroxyvitamin D (25(OH)D) and the risk of prostate cancer (PC).

METHODS

Relevant prospective cohort studies and nested case-control studies published until July 2009 were identified by systematically searching Ovid Medline, EMBASE, and ISI Web of Knowledge databases and by cross-referencing. The following data were extracted in a standardized manner from eligible studies: first author, publication year, country, study design, characteristics of the study population, duration of follow-up, PC incidence/PC mortality according to serum vitamin D status and the respective risk ratios, and covariates adjusted for in the analysis. Due to the heterogeneity of studies in categorizing serum vitamin D levels, all results were recalculated for an increase in serum 25(OH)D by 10ng/ml. Summary odds ratios (ORs) were calculated using meta-analysis methods.

RESULTS

Overall, eleven original articles were included, ten of which reported on the association between serum vitamin D levels and PC incidence and one article reported on the association with PC mortality. Meta-analysis of studies on PC incidence resulted in a summary OR (95% confidence interval, CI) of 1.03 (0.96-1.11) associated with an increase of 25(OH)D by 10ng/ml (P=0.362). No indication for heterogeneity and publication bias was found.

CONCLUSIONS

According to available evidence from longitudinal studies, serum 25(OH)D is not associated with PC incidence.

Critique of the U-shaped serum 25-hydroxyvitamin D level-disease response relation

Previous work has suggested an optimal serum 25-hydroxyvitamin D [25(OH)D] level near 20-30 ng/mL, above which disease risk may increase. Although based primarily on a prostate cancer study in Nordic countries, examples include esophageal, and pancreatic cancer, cardiovascular disease, and all-cause mortality rate. However, these studies apparently are not representative of the findings in the literature for these diseases or disease outcome in general. The prostate cancer study was from Nordic countries and used serum 25(OH)D levels from more than 15 years prior to cancer diagnosis for about half of the cases. Most studies of prediagnostic serum 25(OH)D find no significant correlation with risk of prostate cancer. Many risk-modifying factors for prostate cancer exist that observational studies generally do not include. The esophageal cancer data were from a region of China with high incidence of esophageal cancer. The pancreatic study was conducted on smokers in Finland. Both the esophageal and pancreatic studies are at odds with many ecological and observational studies in various countries. When several studies for cardiovascular disease, and all-cause mortality rate are combined in preliminary meta-analyses, the best fits to the data show a monotonic decrease of hazard ratio with increasing logarithm of serum 25(OH)D. Thus, little support exists for the U-shaped serum 25(OH)D level-disease response relation, and the few studies that do should not be used in forming public health policies regarding vitamin D and ultraviolet-B irradiance.

Duration of vitamin D synthesis from weather model data for use in prospective epidemiological studies

In order to investigate the influence of solar radiation on vitamin D status and its association with different health outcomes in population based studies, appropriate estimates of the subjects' UV radiation exposure are needed. This unique study describes a method that estimates the daily number of vitamin D effective hours (VD-hours) at arbitrary ground locations throughout the period 1957-2002. The method is particularly suited for large-scale prospective epidemiological studies with questionnaire-based information on sun exposure, and where blood measures of vitamin D status are not available. The model takes total cloud cover fraction and total ozone column at noon as input from the ERA-40 data series (i.e. the 40 + year European Centre for Medium-Range Weather Forecasts Re-Analysis archive). By comparing the model results against high accuracy measurements at two different locations in Norway, we found the method for estimating the number of VD-hours to be accurate within 2.5 +/- 7% or better for moderate solar zenith angles (< 65 degrees). For higher solar zenith angles (> 65 degrees) the results are more variable, but the contribution to a population's vitamin D level from solar radiation when the sun is this low in the sky is rather small. The program code to compute VD-hours from ERA-40 files is written in Perl (v 5.8.7) and may be obtained free of charge by contacting corresponding author.

In defense of the sun: An estimate of changes in mortality rates in the United States if mean serum 25-hydroxyvitamin D levels were raised to 45 ng/mL by solar ultraviolet-B irradiance

Emerging scientific evidence strongly supports the beneficial role of vitamin D in reducing the risk of incidence and death from many chronic and infectious diseases. This study estimates increases in melanoma and nonmelanoma skin cancer mortality rates and decreases in chronic and infectious disease mortality rates in the US from the standpoint of approximately doubling population doses of solar UVB to increase mean serum 25-hydroxyvitamin D levels from 16 ng/mL for black Americans and 25 ng/mL for white Americans to 45 ng/mL. The primary benefits are expected to come from reductions in cancer and cardiovascular diseases. Although a few thousand excess deaths per year might occur from melanoma and skin cancer, the avoided premature death rate could be near 400,000/ year, with most of the avoided deaths coming late in life. While oral sources of vitamin D could be used instead of UVB or when UVB irradiance is not available, public health policies do not yet recommend the 3,000-4,000 IU/day required to raise serum 25-hydroxyvitamin D levels to the levels required for optimal health, which would be required before vitamin D fortification levels in food can be raised. Until then, moderate solar UVB irradiance remains an import source, and the health benefits greatly outweigh the risks.

A population-based cohort study on sun habits and endometrial cancer

Background:

No large cohort study has examined the risk of endometrial cancer in relation to sun exposure.

Methods:

A population-based cohort study of 29 508 women who answered a questionnaire in 1990–92, of whom 24 098 responded to a follow-up enquiry in 2000–02. They were followed for an average of 15.5 years.

Results:

Among the 17 822 postmenopausal women included, 166 cases of endometrial cancer were diagnosed. We used a multivariate Cox regression analysis adjusting for age and other selected demographic variables to determine the risk of endometrial cancer. Women using sun beds >3 times per year reduced their hazard risk (HR) by 40% (0.6, 95% confidence interval (CI) 0.4–0.9) or by 50% when adjusting for body mass index or physical activity (HR 0.5, 95% CI 0.3–0.9), and those women who were sunbathing during summer reduced their risk by 20% (HR 0.8 95% CI 0.5–1.5) compared with women who did not expose themselves to the sun or to artificial sun (i.e., sun beds).

Conclusion:

Exposure to artificial sun by the use of sun beds >3 times per year was associated with a 40% reduction in the risk of endometrial cancer, probably by improving the vitamin D levels during winter.

Vitamin D receptor polymorphisms in differentiated thyroid carcinoma

BACKGROUND

Vitamin D receptor (VDR) expression has been shown to be upregulated in several tumors and is supposed to represent an important endogenous response to tumor progression. To investigate the role of the VDR gene and its influence on 25(OH)D(3) and 1,25(OH)(2)D(3) plasma levels in thyroid carcinoma, we analyzed four VDR polymorphisms in patients and healthy controls (HC).

METHODS

Patients with thyroid carcinoma (n = 172) (n = 132 for papillary and n = 40 for follicular) and HC (n = 321) were genotyped for the ApaI (rs7975232), TaqI (rs731236), BsmI (rs1544410), and FokI (rs10735810) polymorphisms within the VDR gene and correlated with 25(OH)D(3) and 1,25(OH)(2)D(3) plasma levels.

RESULTS

The genotypes AA of the ApaI (rs7975232) and FF of the FokI (rs10735810) polymorphisms were significantly less frequent (12.5% vs. 35.2% and 25% vs. 42.1%, respectively, both corrected p [p(c)] = 0.04) in patients with follicular thyroid cancer (FTC) than in HC. Additionally, the haplotypes, Ta (57.5% vs. 41.4%; p(c) = 0.0207), af (24.6% vs. 14.3%; p(c) = 0.0116), Tab (51.1% vs. 36.8%; p(c) = 0.0495), and Tabf (18.7% vs. 13.6%; p(c) = 0.0240) were more frequent, whereas the haplotypes AF (17.1% vs. 37.2%; p(c) = 0.0008), BF (11.4% vs. 31.9%; p(c) = 0.012), tF (7.9% vs. 25.5%; p(c) = 0.0016), and tABF (7.6% vs. 23%; p(c) = 0.0115) were less frequent in the FTC patients compared to HC. Neither genotype nor haplotype frequencies differed between patients with papillary thyroid cancer (PTC) and HC. Further, individuals with PTC and FTC had a significantly lower level of circulating 1,25(OH)(2)D(3) compared to controls. In contrast, no differences of the 25(OH)D(3) concentration between patients and HC were observed. VDR polymorphisms were not associated with 25(OH)D(3) and 1,25(OH)(2)D(3) plasma levels.

CONCLUSIONS

Lower circulating levels of 1,25(OH)(2)D(3) are observed in patients with differentiated thyroid carcinoma. Further, while the alleles AA and FF of the ApaI (rs7975232) and FokI (rs10735810) VDR polymorphisms and the haplotype tABF confer to protection from follicular carcinoma, the haplotype Tabf appeared to be associated with an increased FTC risk. Since this is the first report associating VDR polymorphisms with thyroid carcinoma, these findings need to be confirmed in studies with larger numbers of patients.

Ecological studies of ultraviolet B, vitamin D and cancer since 2000

PURPOSE

The purpose of this review is to summarize ecological studies of solar ultraviolet B (UVB), vitamin D and cancer since 2000.

METHODS

The journal literature is surveyed and summarized.

RESULTS

The ecological approach has been the primary tool used during the past two decades to extend the applicability of the UVB-vitamin D-cancer theory to include at least 18 types of cancer. Many of these studies were conducted in the United States, which has the advantages of availability of reliable age-standardized cancer incidence and mortality rate data for geographic areas at various spatial resolutions, and an asymmetric solar UVB dose pattern, with higher UVB irradiance in the west and lower in the east, at any particular latitude. In addition, indices for other cancer risk-modifying factors are readily available including those for smoking, alcohol consumption, ethnic background, urban/rural residence, socioeconomic status, air pollution, and in limited fashion, diet. The ecological approach has also been used to identify latitudinal variations in cancer mortality rates in Australia, China, Japan, and Spain, and in multicountry studies. It has been used to investigate the relative roles of solar UVB and dietary factors on a global scale. The ecological approach has also been applied to cancer survival. Studies in Norway and England found that individuals diagnosed with cancer in summer or fall, when serum 25-hydroxyvitamin D levels are highest, had a milder clinical course and longer survival than those diagnosed in winter or spring.

CONCLUSION

These findings provide strong evidence that vitamin D status plays an important role in controlling the outcome of cancer. Support for the UVB-vitamin D-cancer theory is now scientifically strong enough to warrant use of vitamin D in cancer prevention, and as a component of treatment. More research studies would help to explore whether there are benefits beyond the substantial effects that have been observed.

Estimated benefit of increased vitamin D status in reducing the economic burden of disease in western Europe

Vitamin D has important benefits in reducing the risk of many conditions and diseases. Those diseases for which the benefits are well supported and that have large economic effects include many types of cancer, cardiovascular diseases, diabetes mellitus, several bacterial and viral infections, and autoimmune diseases such as multiple sclerosis. Europeans generally have low serum 25-hydroxyvitamin D [25(OH)D] levels owing to the high latitudes, largely indoor living, low natural dietary sources of vitamin D such as cold-water ocean fish, and lack of effective vitamin D fortification of food in most countries. Vitamin D dose-disease response relations were estimated from observational studies and randomized controlled trials. The reduction in direct plus indirect economic burden of disease was based on increasing the mean serum 25(OH)D level to 40 ng/mL, which could be achieved by a daily intake of 2000-3000 IU of vitamin D. For 2007, the reduction is estimated at euro187,000 million/year. The estimated cost of 2000-3000 IU of vitamin D3/day along with ancillary costs such as education and testing might be about euro10,000 million/year. Sources of vitamin D could include a combination of food fortification, supplements, and natural and artificial UVB irradiation, if properly acquired. Additional randomized controlled trials are warranted to evaluate the benefits and risks of vitamin D supplementation. However, steps to increase serum 25(OH)D levels can be implemented now based on what is already known.

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

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

Solar ultraviolet irradiance and cancer incidence and mortality

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

Solar UV exposure and mortality from skin tumors

Solar ultraviolet radiation (UVR) exposure is clearly associated with increased mortality from nonmelanoma skin cancer--usually squamous cell carcinoma. However, the association with cutaneous melanoma is unclear from the evidence in ecologic studies and the few analytic studies show that high levels of intermittent UV exposure prior to diagnosis are somehow associated with improved survival from melanoma. Understanding this conundrum is critical to present coherent public health messages and to improve the mortality rates from melanoma.

How strong is the evidence that solar ultraviolet B and vitamin D reduce the risk of cancer?: An examination using Hill's criteria for causality

The ultraviolet-B (UVB)-vitamin D-cancer hypothesis was proposed in 1980. Since then, several ecological and observational studies have examined the hypothesis, in addition to one good randomized, controlled trial. Also, the mechanisms whereby vitamin D reduces the risk of cancer have been elucidated. This report aims to examine the evidence to date with respect to the criteria for causality in a biological system first proposed by Robert Koch and later systematized by A. Bradford Hill. The criteria of most relevance are strength of association, consistency, biological gradient, plausibility/mechanisms and experimental verification. Results for several cancers generally satisfy these criteria. Results for breast and colorectal cancer satisfy the criteria best, but there is also good evidence that other cancers do as well, including bladder, esophageal, gallbladder, gastric, ovarian, rectal, renal and uterine corpus cancer, as well as Hodgkin's and non-Hodgkin's lymphoma. Several cancers have mixed findings with respect to UVB and/or vitamin D, including pancreatic and prostate cancer and melanoma. Even for these, the benefit of vitamin D seems reasonably strong. Although ecological and observational studies are not generally regarded as able to provide convincing evidence of causality, the fact that humanity has always existed with vitamin D from solar UVB irradiance means that there is a wealth of evidence to be harvested using the ecological and observational approaches. Nonetheless, additional randomized, controlled trials are warranted to further examine the link between vitamin D and cancer incidence, survival and mortality.

A critical review of Vitamin D and Cancer: A report of the IARC Working Group

The International Agency for Research on Cancer (IARC) released a report, Vitamin D and Cancer, on November 25, 2008. The report focused on the current state of knowledge and level of evidence of a causal association between vitamin D status and cancer risk. Although presenting and evaluating evidence for the beneficial role of UVB and vitamin D in reducing the risk of cancer, it discounted or omitted important evidence in support of the efficacy of vitamin D. The report largely dismissed or ignored ecological studies on the grounds that confounding factors might have affected the findings. The report accepted a preventive role of vitamin D in colorectal cancer but not for breast cancer.The only randomized controlled trial (RCT) on cancer incidence that used a sufficiently high dose of vitamin D (1,100 IU/day) and calcium (1,400-1,500 mg/day) found a 77% reduction in the risk of all-cancer incidence in postmenopausal women who received both, of which approximately 35% reduction in risk was attributed to vitamin D alone. Unfairly, the report dismissed these findings on the basis of a flawed critique.The report called for RCTs of vitamin D supplementation to settle the issue. Although RCTs theoretically would be beneficial, development of sound and effective public health policies does not necessarily depend on them, and the field of vitamin D, calcium and chronic disease has reached the point where RCTs may not be ethical.The IARC report should therefore not form the basis for public health policy decisions.