Overseas Sun Exposure, Nevus Counts, and Premature Skin Aging in Young English Women: A Population-Based Survey

Nevus Variations in the Jordanian Population: Effects of Age, Medical Conditions, Environment, Congenital, Inherited, and Genetic Factors

Background

Nevi is a common benign proliferation of melanin-producing cells. Many triggers can influence their transformation into either benign or malignant, thus it is important to understand these triggers and their incidence across different populations to take adequate prevention. Here, we aim to examine the different etiologies of nevi changes across the Jordanian population.

Methods

We carried out a cross-sectional observational study focusing on patients seeking dermatological consultation for normal nevi or nevi with minimal changes. Demographic and clinical variables were collected from the patient's case history. Nevi's characteristics were also recorded. A skilled dermatologist assessed nevi morphology and changes using the ABCDE criteria for potential signs of melanoma. Nevi biopsy samples were fixed in formalin and sent for histopathological analysis and were stained with hematoxylin and eosin (H&E).

Results

A total of 231 patients were enrolled, with a majority of females (85%) and a median age of 37. Past medical history was positive in 17% of the samples, with hypertension, endocrine diseases, and diabetes mellitus being the most common. The majority of patients (61%) had fewer than three nevi. Changes in nevus size, configuration, and color were reported in 10% of patients, with multiple changes observed in 36% of patients. Microscopic analysis revealed polypoidal intradermal melanocytic blue nevi as the most common histopathological finding (84%). Positive medical history and the number of nevi were significantly associated with nevi changes.

Conclusion

Our results report that the number of nevi, as well as medical history, is linked to changes in their appearance. Additionally, we provide a detailed account of the various types of observed changes and their occurrence rates.

Body Site Distribution of Acquired Melanocytic Naevi and Associated Characteristics in the General Population of Caucasian Adults: A Scoping Review

The number of melanocytic naevi is a major risk factor for melanoma. The divergent pathway hypothesis proposes that the propensity for naevus proliferation and malignant transformation may differ by body site and exposure to ultraviolet (UV) radiation. This scoping review aimed to summarise the evidence on the number and distribution of naevi (≥ 2 mm) on the body overall and by individual anatomical sites in Caucasian adults, and to assess whether studies used the International Agency for Research on Cancer (IARC) protocol to guide naevus counting processes. Systematic searches of Embase and PubMed identified 661 potentially relevant studies, and 12 remained eligible after full-text review. Studies varied widely in their counting protocols, reporting of naevus counts overall and by body sites, and used counting personnel with differing qualifications. Only one study used the IARC protocol. Studies reported that the highest number of naevi was on the trunk in males and on the arms in females. Body sites which receive intermittent exposure to UV radiation had higher density of naevi. Larger naevi (≥ 5 mm) were detected mostly on body sites intermittently exposed to UV radiation, and smaller naevi (< 5 mm) on chronically exposed sites. Studies reported that environmental and behavioural aspects related to UV radiation exposure, as well as genetic factors, all impact body site and size distribution of naevi. This review found that to overcome limitations of the current evidence, future studies should use consistent naevus counting protocols. Skin surface imaging could improve the reliability of findings. An updated IARC protocol is required that integrates these emerging standards and technologies to guide reliable and reproducible naevus counting in the future.

Weather-Related Human Outdoor Behavior with Respect to Solar Ultraviolet Radiation Exposure in a Changing Climate

Climate-related changes in human sun exposure behavior can be an important influence on future ultraviolet radiation (UVR) related disease risks. In particular, active leisure mobility and leisure activities are more dependent on weather conditions than routine activities. However, the direction and extent of the effects vary. For temperate and cold climates, the available studies provide indications that a possible increase in UVR exposure would primarily result from a reduction in clothing and only secondarily from changes in the time spent outdoors. Existing studies suggest a nonlinear, bell-shaped relationship with threshold value effects for the relationship between outdoor time and thermal conditions. If the local climate is already very warm and there are only minor seasonal differences, there is no statistically significant evidence of changes in behavior. If there is significant warm discomfort, there is a tendency to avoid being outdoors or in the sun. It is not justified to simply transfer and generalize results and conclusions to different climates and seasons and between different leisure activities and forms of active mobility. The geographical context must be considered also in terms of cultures and habits, adaptations, traffic and land use (urban, rural). In addition, changes in behavior can develop differently depending on individual characteristics of people such as heat affinity, leisure type, age and gender. Differentiated analyses are required that take into account and balance opposing effects.

Ultraviolet radiation and cutaneous melanoma: a historical perspective

In this article, we summarize the research that eventually led to the classification of the full ultraviolet (UV) radiation spectrum as carcinogenic to humans. We recall the pioneering works that led to the formulation of novel hypotheses on the reasons underlying the increasing burden of melanoma in light-skinned populations. It took long before having compelling evidence on the association between UV and melanoma, in particular, the importance of UV exposure during childhood for both the occurrence of melanoma and death. The role of UVA was established only after 2005. If molecular lesions caused by UV radiation are better known, the precise mechanism by which UV exposure drives melanoma occurrence and progression still needs to be elucidated. More research on the UV-melanoma relationships has led to more evidence-based sun-protection recommendations, especially for children, and to effective control of the artificial UV tanning fashion. Since around 1985-1995, the mortality because of melanoma has started to decrease in younger age groups in most light-skinned populations. If sun protection among children remain on top of public health agendas, there is a fairly great chance that melanoma mortality will stabilize and steadily decrease in all light-skinned populations. The introduction of effective therapies against metastatic disease will improve this reversal in mortality trends.

Body site-specific genetic effects influence naevus count distribution in women

Body site is highly relevant for melanoma: it affects prognosis and varies according to the patient's sex. The distribution of naevi, a major risk factor for melanoma, at different body sites also varies according to sex in childhood. Using naevus counts at different body sites in 492 unrelated adults from both sexes, we observed that women have an increased number of naevi on the lower limbs compared to men (p = 8.5 × 10^-5 ), showing that a high naevus count on this site persists from childhood throughout life. Then, using data from 3,232 twins, we observed, in women, the lowest naevus count heritability on the trunk (26%), and the highest on the lower limbs (69%). Finally, we showed that, in 2,864 women, six genomic loci previously associated with both naevus count and melanoma risk (IRF4, DOCK8, MTAP, 9q31.2, KITLG and PLA2G6) have an effect on naevus count that is body site-specific, but whose effect sizes are predominantly stronger on the lower limbs. Sex-specific genetic influence on naevus count at different sites may explain differences in site-specific melanoma incidence as well as prognosis between sexes.

Future reduction of cutaneous malignant melanoma due to improved sun protection habits and decreased common melanocytic nevi density among Swedish children?: A follow-up from 2002 to 2012

We have previously demonstrated significant improvements in sun protection regimens and significantly fewer common melanocytic nevi (CMN) among 7-year-old children in southern Sweden when comparing year 2007 with 2002. The aim of this study was to investigate whether the observed decreasing trend also can be observed at age 10 and, in addition, to compare the CMN density change between 7 and 10 years of age during two periods of time. Two open cohorts were used, cohort I with schoolchildren investigated in 2002 at age 7 and in 2005 at age 10 and cohort II with schoolchildren investigated in 2009 at age 7 and in 2012 at age 10. A significant decrease in CMN density (number/m² BSA) at age 10 from 2005 to 2012 was observed: 15.9 (14.7-17.2) and 11.4 (10.1-12.7), respectively. The density growth rate from 7 to 10 years was 2.8 (2.1-3.5) between 2002 and 2005 and decreased significantly to 0.9 (0.2-1.5) between 2009 and 2012. Significant increases were observed for 'often use of sunscreen', 'often staying in shade' and 'often staying indoors' from cohort I to cohort II: 65 vs 80%, 7.6 vs 13% and 7.3 vs 19%, respectively. The decrease in number of CMN among 10-year-old children confirms a current trend in Sweden. If this persists, a future reduction of cutaneous malignant melanoma incidence in Sweden might be anticipated. The results also indicate that CMN count could be used as an indicator of ultraviolet exposure.

Reliability and consistency of a validated sun exposure questionnaire in a population-based Danish sample

An important feature of questionnaire validation is reliability. To be able to measure a given concept by questionnaire validly, the reliability needs to be high.

The objectives of this study were to examine reliability of attitude and knowledge and behavioral consistency of sunburn in a developed questionnaire for monitoring and evaluating population sun-related behavior.

Sun related behavior, attitude and knowledge was measured weekly by a questionnaire in the summer of 2013 among 664 Danes. Reliability was tested in a test-retest design. Consistency of behavioral information was tested similarly in a questionnaire adapted to measure behavior throughout the summer.

The response rates for questionnaire 1, 2 and 3 were high and the drop out was not dependent on demographic characteristic. There was at least 73% agreement between sunburns in the measurement week and the entire summer, and a possible sunburn underestimation in questionnaires summarizing the entire summer. The participants underestimated their outdoor exposure in the evaluation covering the entire summer as compared to the measurement week. The reliability of scales measuring attitude and knowledge was high for majority of scales, while consistency in protection behavior was low.

To our knowledge, this is the first study to report reliability for a completely validated questionnaire on sun-related behavior in a national random population based sample. Further, we show that attitude and knowledge questions confirmed their validity with good reliability, while consistency of protection behavior in general and in a week's measurement was low.

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Objectively validated questionnaires tested for reliability/behavioral consistency.

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Strong reliability of the knowledge and attitude items was shown.

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Knowledge about behavioral consistency between questionnaire measurement periods

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A recommendable design for short term evaluation of skin cancer prevention campaigns

A Randomized Trial of an Advanced Sun Safety Intervention for Vacationers at 41 North American Resorts

Taking vacations in sunny locations is associated with the development of skin cancer. This study tested a multi-component sun protection intervention based on diffusion of innovations theory and transportation theory designed to increase vacationers' comprehensive sun protection, i.e., use of clothing, hats, and shade, and use, pre-application, and reapplication of sunscreen. The trial enrolled 41 warm weather resorts in North America in a pair-matched group randomized pretest-posttest design and assessed samples of adult vacationers at resort outdoor recreation venues regarding sun protection at pretest (n = 3,531) and posttest (n = 3,226). While results showed no overall effect of the intervention on comprehensive sun protection across venues, the intervention produced statistically significant improvements in sun protection at waterside venues (pools and beaches). The intervention's overall effects may have been impeded by a lack of uniformly robust implementation, low interest in skin cancer prevention by guests, or shortcomings of the theories used to create prevention messages. The intervention may have worked best with guests in the highest-risk recreation venue, i.e., waterside recreation where they exposed the most skin. Alternative approaches that alter resort organizations, such as through changes in policy, environmental features, or occupational efforts might be more effective than targeting vacationers with behavior-change messages.

Effect of an intervention on observed sun protection by vacationers in a randomized controlled trial at North American resorts

During vacations, many individuals receive high-risk sun exposure that is associated with skin cancer. Vacationers in outdoor recreation venues (pretest n=4347; posttest n=3986) at warm-weather destination resorts in North America (n=41) were enrolled in a pair-matched, group-randomized pretest-posttest controlled quasi-experimental design in 2012-14. Print, audiovisual, and online messages based on Transportation Theory and Diffusion of Innovation Theory and promoting advanced sun protection (e.g., use of clothing, hats, shade and pre-application/reapplication of sunscreen and reliable cues to high UV) were delivered through resort channels. Vacationers' sun protection practices observed by trained research staff (i.e., body coverage and shade use analyzed individually and in combined scores) did not differ by experimental condition (p>0.05) or intervention implementation (p>0.05). However, recreation venue moderated intervention impact. The intervention improved sun protection at waterside recreation venues (z-score composite: intervention pre=-22.74, post=-15.77; control pre=-27.24, post=-23.24) but not non-waterside venues (z-score composite: intervention pre=20.43, post=20.53; control pre=22.94, post=18.03, p<0.01). An additional analysis showed that resorts with greater program implementation showed more improvements in sun protection by vacationers at waterside (z=score composite: high implementation pre=-25.45, post=-14.05; low implementation pre=-24.70, post=-21.40) compared to non-waterside (z-score composite: high implementation pre=14.51, post=19.98; low implementation pre=24.03, post=18.98, p<0.01) recreation venues. The intervention appeared effective with the vacationers in recreation venues with the highest-risk for sun exposure, waterside venues. However, it was not effective throughout all the resort venues, possibly because of the sun-seeking desires of vacationers, information overload at the resorts, and constraints on clothing styles and sun protection by recreation activity.

Prevalence of Sun Protection at Outdoor Recreation and Leisure Venues at Resorts in North America

Background

Exposure to solar ultra violet radiation (UVR) is a primary risk factor for skin cancer. Vacationers often fail to protect themselves from harmful UVR.

Purpose

The study assessed the sun protection practices of resort guests in various outdoor leisure and recreation venues during warm-weather seasons.

Method

41 North American resorts were enrolled in a quasi-experimental randomized controlled trial. Adult guests were observed (n=4091) and surveyed (n=3694) in a cross sectional sample. Data collection was conducted in recreation and leisure venues with outdoors commons/reception areas acting as the comparison condition.

Results

The mean percent of vacationers at pools and beaches were more likely (p < 0.001) to wear sunscreen than in commons areas but less likely (p < 0.001) to wear cover-up clothing or use shade. In both samples, the combined sun protection scores were higher in commons areas compared to all venues except for outdoor dining (p < 0.001).

Discussion

Sun safety was suboptimal in all venues and was potentially mitigated by venue type.

Translation to Health Education Practice

Approaches are needed to encourage vacationers to practice comprehensive sun protection and to work with resorts to construct built environments that facilitate rather than act as barriers to sun safety.

Skin microtopography as a measure of photoaging and risk of squamous cell carcinoma of the skin in a US population

BACKGROUND

Skin microtopography as a measure of photoaging is a noninvasive approach to measuring chronic ultraviolet radiation exposure and reflects the degree of dermal elastosis in populations of European descent in the subtropics. Less is known about the utility of this approach in populations at different latitudes, and whether it relates to skin cancer risk.

METHODS

A population-based case-control study of 342 squamous cell carcinoma (SCC) cases and 331 age- and gender-matched controls were evaluated for histologic evidence of solar damage and severity of photoaging based on microtopography on a six-grade scale. Odds ratios (OR) for SCC associated with degree of photoaging were estimated using logistic regression analysis adjusted for potentially confounding factors.

RESULTS

After adjustment for known risk factors, SCC was associated with increasing photoaging grade (OR = 1.7, 95% CI = 0.9-3.0 for severe photoaging; OR = 2.8, 95% CI = 1.6-5.0 for very severe photoaging). Associations remained among those with actinic keratosis (OR = 3.4, 95% CI = 0.9-12.4 for severe photoaging, OR = 5.7, 95% CI = 1.7-19.6 for very severe photoaging).

LIMITATIONS

There was limited statistical power, particularly for subgroup analyses.

CONCLUSION

Our findings provide further evidence of microtopography as an independent, objective indicator of risk of SCC.

Defining "intermittent UVR exposure"

BACKGROUND

Cutaneous malignant melanoma (CMM) has been associated with "intermittent UVR exposure", which in previous studies has mainly been assessed by retrospective questionnaire data. Further, there is no uniform definition of the term "intermittent UVR exposure".

OBJECTIVES

We aimed to define and quantify "intermittent UVR exposure" by an objective measure.

METHODS

A broad study population of adults and children had data collected during a summer period. Data were personal UVR dosimetry measurements, from which the number of "intermittent days" was derived, sun behaviour diaries and retrospective questionnaires. Two definitions of intermittent UVR exposure were tested: (1) days when UVR dose exceeded 3 times individual average daily UVR dose, and (2) days when UVR dose exceeded individual constitutive skin type. Measures of nevi and lentigines were used as surrogates for CMM.

RESULTS

Using the first definition based solely on UVR dosimetry data we found 1241 "intermittent days" out of a total of 17 277 days (7.2%) among 148 participants. The numbers for nevi and lentigo density were significantly predicted by the number of intermittent days (R(2) = 0.15 and R(2) = 0.40, p < 0.001). The corresponding numbers for prediction of nevi and lentigo density by retrospective questionnaire data was lower (R(2) = 0.11, R(2) = 0.26, p < 0.001).

CONCLUSIONS

We introduce a well-defined objective measure of intermittent UVR exposure. This measure may provide a better prediction of solar skin damage and CMM than retrospective questionnaire data.

Environmental variables associated with vacationers' sun protection at warm weather resorts in North America

BACKGROUND

Vacationing at sunny, warm weather locations is a risk factor for excessive solar ultraviolet (UV) radiation exposure and skin cancer.

OBJECTIVES

This study examined the association of environmental variables related to UV levels with vacationers' sun protection.

METHODS

Vacationers at 41 summer resorts in 17 states and 1 Canadian Province were interviewed (n=3531) and observed (N=4347) during 2012 and 2013. Clothing coverage, sunglasses, and shade use were observed. Use of sunscreen and sunburns were self-reported. Environmental information was recorded by research staff or acquired from ground stations and the weather service.

RESULTS

Temperature was positively associated with sun protection behaviors; however clothing coverage was negatively associated with temperature. Cloud cover was negatively associated with sun protection, with the exception of clothing coverage which was positively associated with it. Elevation showed a mixed pattern of associations with vacationer's sun protection. Latitude of a resort was negatively associated with most sun protection behaviors, such that sun protection increased at more southerly resorts. Similarly, the farther south a vacationer traveled to the resort, the less sun protection they employed. The UV index showed a weak, positive relationship with some sun protection behaviors even when controlling for temperature.

CONCLUSIONS

Vacationers appeared aware that UV is higher at southern latitudes and may learn UV is intense when living in southern regions. However, many used temperature, an unreliable cue, to judge UV intensity and seemed to adjust clothing for warmth not UV protection. Efforts are needed to help individuals make more accurate sun safety decisions.

Rationale, design, samples, and baseline sun protection in a randomized trial on a skin cancer prevention intervention in resort environments

INTRODUCTION

Exposure to solar ultraviolet radiation during recreation is a risk factor for skin cancer. A trial evaluated an intervention to promote advanced sun protection (sunscreen pre-application/reapplication; protective hats and clothing; use of shade) during vacations.

MATERIALS AND METHODS

Adult visitors to hotels/resorts with outdoor recreation (i.e., vacationers) participated in a group-randomized pretest-posttest controlled quasi-experimental design in 2012-14. Hotels/resorts were pair-matched and randomly assigned to the intervention or untreated control group. Sun. protection (e.g., clothing, hats, shade and sunscreen) was measured in cross-sectional samples by observation and a face-to-face intercept survey during two-day visits.

RESULTS

Initially, 41 hotel/resorts (11%) participated but 4 dropped out before posttest. Hotel/resorts were diverse (employees=30 to 900; latitude=24° 78' N to 50° 52' N; elevation=2ft. to 9726ft. above sea level), and had a variety of outdoor venues (beaches/pools, court/lawn games, golf courses, common areas, and chairlifts). At pretest, 4347 vacationers were observed and 3531 surveyed. More females were surveyed (61%) than observed (50%). Vacationers were mostly 35-60years old, highly educated (college education=68%) and non-Hispanic white (93%), with high-risk skin types (22%). Vacationers reported covering 60% of their skin with clothing. Also, 40% of vacationers used shade; 60% applied sunscreen; and 42% had been sunburned.

CONCLUSIONS

The trial faced challenges recruiting resorts but result showed that the large, multi-state sample of vacationers were at high risk for solar UV exposure.

Connectedness to nature and public (skin) health perspectives: results of a representative, population-based survey among Austrian residents

Connectedness to nature (CN) influences motivation to have contact with outdoor natural environments. Spending leisure time in natural environments is beneficial for human health and well-being. Besides these positive effects, health risks of open-air activities are mainly related to unprotected sun light exposure-associated acute and chronic skin hazards. Thus, we conducted a cross-sectional, representative telephone survey among Austrian residents to study the association of perceived CN level with sun-exposure knowledge, tanning habits, and sun protective behaviour. In total, 1,500 study subjects (50.5% females) participated in this questionnaire survey. Although knowledge about tanning and motives to tan were similar among genders, females performed more photoprotective measures and were more connected to nature (all p < 0.001) compared to males. Older age and outdoor sport were significant gender-independent predictor variables influencing perceived CN level. Additionally, level of education was relevant in male CN, whereas non-smoking and higher knowledge were predictive of female CN. This survey provides so far unreported empirical data on the relationship between nature connectedness and skin health-relevant recreational habits of Austrian residents. The findings suggest to integrate hitherto neglected gender-specific Public (Skin) Health promotion when counselling on the manifold health advantages of outdoor activities.

Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin--a case-control study

BACKGROUND

Non-melanoma skin cancer (NMSC), comprised of basal (BCC) and squamous (SCC) cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type.

METHODS

A case-control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous) and timing (childhood vs. adulthood) of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers.

RESULTS

A history of blistering sunburn (a measure of intermittent sunlight exposure) was associated with both BCC (OR = 1.96, 95% CI = 1.27-3.03) and SCC (OR = 2.02, 95% CI = 1.22-3.33). Additionally, having a job in the sun for ≥ 3 months for 10 years or longer (a measure of continuous sunlight exposure) was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk.

CONCLUSIONS

Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous). The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC.

Vacations to sunny destinations, sunburn, and intention to tan: A cross-sectional study in Denmark, 2007-2009

Background: Denmark has experienced an increase in melanoma incidence since the 1960s. Exposure to ultraviolet radiation is the main preventable cause of this cancer. We examined current travel to, and sun-related behaviour of Danes at, sunny destinations in relation to their risk for sunburn. Method: A population-based sample of 11,158 respondents aged 15—59 years completed three questionnaires in 2007—2009 that included items on exposure to ultraviolet radiation. Using logistic regression analysis we examined the relations between sunny vacations, sun-related behaviour, demographic factors and risk for sunburn. Results: During 2007—2009, 44.8—45.8% of the respondents travelled to a sunny destination at least once a year; 24% became sunburnt, and 69% tanned intentionally. The odds ratio for sunburn in general for people who went on a sunny vacation as compared with those who did not was 1.6 (1.5—1.7). Sunscreen use (1.9; 1.4—2.6) and intentional tanning (3.4; 2.8—4.1) were positively associated with sunburn on vacation. Conclusions: Taking a vacation in a sunny place is a risk factor for sunburn, especially for young people. The recommendation for sunscreen use should be re-evaluated, as intention to tan is the most important factor in sunburn on vacation and should be targeted more strategically.

Melanocytic nevi, nevus genes, and melanoma risk in a large case-control study in the United Kingdom

BACKGROUND

Increased number of melanocytic nevi is a potent melanoma risk factor. We have carried out a large population-based case-control study to explore the environmental and genetic determinants of nevi and the relationship with melanoma risk.

METHODS

We report nevus phenotype in relation to differing patterns of sun exposure, inherited variation at loci shown in recent genome-wide association studies to be nevus genes, and risk.

RESULTS

Increased numbers of nevi were associated with holiday sun exposure, particularly on intermittently sun-exposed body sites (test for P(trend) < 0.0001). Large nevi were also associated with holiday sun exposure (P = 0.002). Single nucleotide polymorphisms (SNP) on chromosomes 9 and 22 were associated with increased numbers of nevi (P = 0.04 and P = 0.002 respectively) and larger nevi (P = 0.03 and P = 0.002), whereas that on chromosome 6 was associated only with large nevi (P = 0.01). Melanoma risk was associated with increased nevus count, large nevi, and atypical nevi for tumors in all body sites (including rare sites) irrespective of age. The risk persisted when adjusted for inheritance of nevus SNPs.

CONCLUSIONS

The at-risk nevus phenotype is associated with behaviors known to increase melanoma risk (holiday sun exposure). Although SNPs on chromosomes 6, 9, and 22 were shown to be nevus genes, they explained only a small proportion of melanoma risk and nevus phenotype; therefore, several nevus genes likely remain to be identified.

IMPACT

This article confirms the importance of nevi in melanoma pathogenesis and increases understanding of their genetic determinants.

Latitude gradient for melanoma incidence by anatomic site and gender in Norway 1966-2007

Latitude gradients and time trends for cutaneous malignant melanoma (CMM) were analyzed using incident cases from the Norwegian Cancer Registry for the period 1966-2007. Sex and various anatomic regions of the body were taken into account, for better understanding of the role of ultraviolet radiation in CMM etiology. There is a latitude gradient for CMM on all body sites included in the present study, with 2-2.5 times higher incidence rates in the south. The latitude gradients seem to be largest for the trunk. Melanomas on sites intermittently exposed to the sun (like the trunk) dominate both in the north and in the south and this distribution has not changed over the years. A leveling off of the incidence rates are observed for both sexes and for all sites studied, after 1985-1995, slightly more in the south than in the north, except for the head and neck where the incidence rates have continued to increase slowly in the north as well as in the south. The leveling off of melanoma trend is probably associated with melanoma prevention campaigns and with increasing awareness, although vitamin D could play a role.

Zebrafish have a competent p53-dependent nucleotide excision repair pathway to resolve ultraviolet B-induced DNA damage in the skin

Ultraviolet (UV) light is a primary environmental risk factor for melanoma, a deadly form of skin cancer derived from the pigmented cells called melanocytes. UVB irradiation causes DNA damage, mainly in the form of pyrimidine dimers (cis-syn cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts), and organisms have developed complex multiprotein repair processes to cope with the DNA damage. Zebrafish is becoming an important model system to study the effects of UV light in animals, in part because the embryos are easily treated with UV irradiation, and the DNA damage repair pathways appear to be conserved in zebrafish and mammals. We are interested in exploring the effects of UV irradiation in young adult zebrafish, so that we can apply them to the study of gene-environment interactions in models of skin cancer. Using the Xiphophorus UV melanoma model as a starting point, we have developed a UV irradiation treatment chamber, and established UV treatment conditions at different ages of development. By translating the Xiphophorus UV treatment methodology to the zebrafish system, we show that the adult zebrafish skin is competent for nucleotide excision DNA damage repair, and that like in mammalian cells, UV treatment promotes phosphorylation of H2AX and a p53-dependent response. These studies provide the groundwork for exploring the role of UV light in melanoma development in zebrafish.

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.