Nevus density and melanoma risk in women: a pooled analysis to test the divergent pathway hypothesis

The Risk of Melanoma due to Exposure to Sun and Solarium Use in Poland: A Large-Scale, Hospital Based Case - Control Study

OBJECTIVE

The incidence of skin cancer is constantly growing, it is considered a serious problem of public health. Most cases of skin cancer are caused by a combination of non-modifiable genetic, and modifiable environmental risk factors. The study objective was to analyse the correlation between pigmentation traits, excessive sunlight exposure, solarium use and the risk of melanoma development.

METHODS

The study included 480 patients diagnosed with melanoma and 400 within the control group. Subjects diagnosed with the melanoma confirmed by histopathology were invited to take part in the study. The research was based on a clinical, direct, individual, structured, in-depth and focused interview.

RESULTS

The mean age of the study subjects was 44.3 ± 7.86, while in the control group 59.5 (7.93) Most frequently, melanoma was located on the upper extremities (64%). A family history of neoplastic diseases was found in 55% of the patients. The assessment of sunburns showed that only 15%  of the respondents never experienced sunburn, 49% of the study subjects never used solarium. Among patients with multiple sunburns, the risk of developing skin cancer was 1.27 (AOR = 1,27; 95% CI, 1.07-1.55) compared with non-sunburns subjects.

CONCLUSIONS

Risky behaviours including excessive exposure to UV radiation, both natural and artificial, are of special significance in women with fair complexion and fair hair. Indoor tanning is a probable factor of increased skin cancer incidence in younger women, as compared to men.

Skin Cancer Management: Current Scenario And Future Perspectives

Skin cancer is a life-threatening disease and has caused significant loss to human health across the globe. Its prevalence has been increasing every year and is one of the common malignancies in the case of organ transplant recipients, of which 95% constitute basal cell and squamous cell carcinomas. The prime factor causing skin cancer is UV radiation. Around the 20th century, sunlight was the primary cause of skin cancer. A novel hypothesis by US scientists stated that cutaneous melanoma was mainly due to recurrent exposure to the sun, whereas keratinocyte cancer occurred due to progressive accumulation of sun exposure. Management of skin cancer is done via various approaches, including cryotherapy, radiotherapy, and photodynamic therapy. Post-discovery of X-rays, radiotherapy has proven to treat skin cancers to some extent, but the indications are uncertain since it depends upon the type of tumour and surgical treatment required for the patient. Due to various limitations of skin cancer treatment and increased severity, there is a requirement for cost-effective, novel, and efficient treatment. Various nanocarriers such as SLNs, magnetic nanoparticles, gold nanoparticles, carbon nanotubes, etc., are the potential carriers in the management and prognosis of both non-melanoma and melanoma skin cancer. Various research and review databases and patent reports have been studied, and information compiled to extract the results. The review also discusses the role of various nanocarriers in treating and diagnosing skin cancer.

Analyzing the Spatial Randomness in the Distribution of Acquired Melanocytic Neoplasms

On the basis of the clinical impression and current knowledge, acquired melanocytic nevi and melanomas may not occur in random localizations. The goal of this study was to identify whether their distribution on the back is random and whether the location of melanoma correlates with its adjacent lesions. Therefore, patient-level and lesion-level spatial analyses were performed using the Clark‒Evans test for complete spatial randomness. A total of 311 patients with three-dimensional total body photography (average age of 40.08 [30‒49] years; male/female ratio: 128/183) with 5,108 eligible lesions in total were included in the study (mean sum of eligible lesions per patient of 16.42 [3‒199]). The patient-level analysis revealed that the distributions of acquired melanocytic neoplasms were more likely to deviate toward clustering than dispersion (average z-score of ‒0.55 [95% confidence interval = ‒0.69 to ‒0.41; P < 0.001]). The lesion-level analysis indicated a higher portion of melanomas (n = 57 of 72, 79.2% [95% confidence interval = 69.4‒88.9%]) appearing in proximity to neighboring melanocytic neoplasms than to nevi (n = 2,281 of 5,036, 45.3% [95% confidence interval = 43.9‒46.7%]). In conclusion, the nevi and melanomas' distribution on the back tends toward clustering as opposed to dispersion. Furthermore, melanomas are more likely to appear proximally to their neighboring neoplasms than to nevi. These findings may justify various oncogenic theories and improve diagnostic methodology.

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.

Melanoma therapeutics: a literature review

Melanoma is a relentless type of skin cancer which involves myriad signaling pathways which regulate many cellular processes. This makes melanoma difficult to treat, especially when identified late. At present, therapeutics include chemotherapy, surgical resection, biochemotherapy, immunotherapy, photodynamic and targeted approaches. These interventions are usually administered as either a single-drug or in combination, based on tumor location, stage, and patients' overall health condition. However, treatment efficacy generally decreases as patients develop treatment resistance. Genetic profiling of melanocytes and the discovery of novel molecular factors involved in the pathogenesis of melanoma have helped to identify new therapeutic targets. In this literature review, we examine several newly approved therapies, and briefly describe several therapies being assessed for melanoma. The goal is to provide a comprehensive overview of recent developments and to consider future directions in the field of melanoma.

Magnetic nanoparticles in theranostics of malignant melanoma

Malignant melanoma is an aggressive tumor with a tendency to metastasize early and with an increasing incidence worldwide. Although in early stage, melanoma is well treatable by excision, the chances of cure and thus the survival rate decrease dramatically after metastatic spread. Conventional treatment options for advanced disease include surgical resection of metastases, chemotherapy, radiation, targeted therapy and immunotherapy. Today, targeted kinase inhibitors and immune checkpoint blockers have for the most part replaced less effective chemotherapies. Magnetic nanoparticles as novel agents for theranostic purposes have great potential in the treatment of metastatic melanoma. In the present review, we provide a brief overview of treatment options for malignant melanoma with different magnetic nanocarriers for theranostics. We also discuss current efforts of designing magnetic particles for combined, multimodal therapies (e.g., chemotherapy, immunotherapy) for malignant melanoma.

Genetically determined cutaneous nevi and risk of cancer

Numerous epidemiologic studies have reported positive associations between higher nevus counts and internal cancers. Whether this association represents a true relationship or is due to bias or confounding by factors associated with both nevus counts and cancer remains unclear. We used germline genetic variants for nevus count to test whether this phenotypic trait is a risk-marker for cancer. We calculated polygenic risk scores (PRS) for nevus counts using individual-level data in the UK Biobank (n = 394 306) and QSkin cohort (n = 17 427). The association between the nevus PRS and each cancer site was assessed using logistic regression adjusted for the effects of age, sex and the first five principal components. In both cohorts, those in the highest nevus PRS quartile had higher risks of melanoma than those in the lowest quartile (UK Biobank odds ratio [OR] 1.42, 95% confidence interval [CI]: 1.29-1.55; QSkin OR 1.58, 95% CI: 1.29-1.94). We also observed increases in risk of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) associated with higher nevus PRS quartiles (BCC UK Biobank OR 1.38, 95% CI: 1.33-1.44; QSkin OR 1.20, 95% CI: 1.05-1.38 and SCC UK Biobank OR 1.41, 95% CI: 1.28-1.55; QSkin OR 1.44, 95% CI: 1.19-1.77). We found no consistent evidence that nevus count PRS were associated with risks of developing internal cancers. We infer that associations between nevus counts and internal cancers reported in earlier observational studies arose because of unmeasured confounding or other biases.

Dermatologic Follow-up and Assessment of Suspicious Lesions

As our knowledge and understanding of melanoma evolve, melanoma surveillance guidelines will reflect these findings. Currently, there is no consensus across international guidelines for melanoma follow-up. However, it is accepted that more aggressive surveillance is recommended for more advanced disease. When examining high-risk individuals, a systematic approach should be followed. Future considerations include the use of noninvasive imaging techniques, 'liquid biopsies,' and artificial intelligence to enhance detection of melanomas.

Differences in Melanoma Between Canada and New South Wales, Australia: A Population-Based Genes, Environment, and Melanoma (GEM) Study

In an effort to understand the difference between melanomas diagnosed in Australia (New South Wales) and Canada, where the incidence in New South Wales is almost three times greater than in Canada, and mortality is twice as high although survival is slightly more favorable, we had one pathologist review 1,271 melanomas from British Columbia and Ontario, Canada, to compare these to melanomas in New South Wales, Australia. We hypothesized that histopathologic characteristics might provide insight into divergent pathways to melanoma development. We found a number of differences in risk factors and tumor characteristics between the two geographic areas. There were higher mole counts and darker phenotypes in the Canadian patients, while the Australian patients had greater solar elastosis, more lentigo maligna melanomas, and more tumor infiltrating lymphocytes. We hypothesize that the differences observed may illustrate different etiologies – the cumulative exposure pathway among Australian patients and the nevus pathway among Canadian patients. This is one of the largest studies investigating the divergent pathway hypothesis and is particularly robust due to the evaluation of all lesions by one dermatopathologist.

On Naevi and Melanomas: Two Sides of the Same Coin?

Benign naevi are closely linked to melanoma, as risk factors, simulators, or sites of melanoma formation. There is a heavy genetic overlap between the two lesions, a shared environmental influence of ultraviolet radiation, and many similar cellular features, yet naevi remain locally situated while melanomas spread from their primary site and may progress systemically to distal organs. Untangling the overlapping contributors and predictors of naevi and melanoma is an ongoing area of research and should eventually lead to more personalized prevention and treatment strategies, through the development of melanoma risk stratification tools and early detection of evolving melanomas. This will be achieved through a range of complementary strategies: risk-adjusted primary prevention counseling; the use of lesion imaging technologies such as sequential 3D total body photography and consumer-performed lesion imaging; artificial intelligence deep phenotyping and clinical assistance; a better understanding of genetic drivers of malignancy, risk variants, clinical genetics, and polygenic effects; and the interplay between genetics, phenotype and the environment.

Parkinson's Disease and Melanoma: Co-Occurrence and Mechanisms

Parkinson's disease (PD) is a neurodegenerative disorder that is characterized by loss of dopaminergic neurons in the substantia nigra pars compacta, depletion of dopamine in the striatum and the presence of Lewy bodies. Cancer is uncontrolled growth of cells in the body and migration of these cells from their site of origin to other parts of the body. PD and cancer are two opposite diseases, one arising from cell proliferation and the other from cell degeneration. This fundamental difference is consistent with inverse comorbidity between most cancers and neurodegenerative diseases. However, a positive association of PD and melanoma has been reported which has recently become of significant interest. A link between PD and cancer has been supported by many epidemiological studies, most of which show that PD patients have a lower risk of developing most cancers than the general population. However, the mechanisms underlying this epidemiological observation are not known. In this review we focus on epidemiological studies correlating PD and melanoma and the possible mechanisms underlying the co-occurrence of the two diseases. We explore possible explanations for the important observations that more PD patients develop melanoma that would otherwise be expected and vice-versa.

Associations of pigmentary and naevus phenotype with melanoma risk in two populations with comparable ancestry but contrasting levels of ambient sun exposure

BACKGROUND

People at high risk of developing melanoma are usually identified by pigmentary and naevus phenotypes.

OBJECTIVE

We examined whether associations of these phenotypes with melanoma risk differed by ambient sun exposure or participant characteristics in two population-based, case-control studies with comparable ancestry but different ambient sun exposure.

METHODS

Data were analysed from 616 cases and 496 controls from the Australian Melanoma Family Study and 2012 cases and 504 controls from the Leeds (UK) case-control study. Questionnaire, interview and dermatological skin examination data were collected using the same measurement protocols. Relative risks were estimated as odds ratios using unconditional logistic regression, adjusted for potential confounders.

RESULTS

Hair and skin colour were the strongest pigmentary phenotype risk factors. All associations of pigmentary phenotype with melanoma risk were similar across countries. The median number of clinically assessed naevi was approximately three times higher in Australia than Leeds, but the relative risks for melanoma associated with each additional common or dysplastic naevus were higher for Leeds than Australia, especially for naevi on the upper and lower limbs. Higher naevus counts on the head and neck were associated with a stronger relative risk for melanoma for women than men. The two countries had similar relative risks for melanoma based on self-reported naevus density categories, but personal perceptions of naevus number differed by country. There was no consistent evidence of interactions between phenotypes on risk.

CONCLUSIONS

Classifying people at high risk of melanoma based on their number of naevi should ideally take into account their country of residence, type of counts (clinical or self-reported), body site on which the naevus counts are measured and sex. The presence of naevi may be a stronger indicator of a genetic predisposition in the UK than in Australia based on less opportunity for sun exposure to influence naevus development.

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.

Association of Phenotypic Characteristics and UV Radiation Exposure With Risk of Melanoma on Different Body Sites

Importance

Two pathways have been hypothesized for the development of cutaneous melanoma: one typically affects the head and neck, a site with chronic sun damage, and the other affects the trunk, which is less exposed to the sun. However, the possible cause of limb melanomas is less studied under this hypothesis.

Objective

To investigate the association between phenotypic characteristics, pattern of UV radiation exposure, and risk of melanoma on different body sites.

Design, Setting, and Participants

This study used data on 161 540 women with information on phenotypic characteristics and UV radiation exposure who were part of the Norwegian Women and Cancer study, a population-based prospective study established in 1991 with exposure information collected by questionnaires at baseline and every 4 to 6 years during follow-up through 2015. Data analysis was performed from October 2017 through May 2018.

Exposures

Participants reported hair color, eye color, untanned skin color, number of small symmetric and large asymmetric nevi, and freckling, as well as histories of sunburns, sunbathing vacations, and indoor tanning in childhood, adolescence, and adulthood.

Main Outcomes and Measures

The Norwegian Women and Cancer study was linked to the Cancer Registry of Norway for data on cancer diagnosis and date of death or emigration. Primary melanoma site was categorized as head and neck, trunk, upper limbs, and lower limbs.

Results

During follow-up of the 161 540 women in the study (mean age at study entry, 50 years [range, 34-70 years]; mean age at diagnosis, 60 years [range, 34-87 years]), 1374 incident cases of melanoma were diagnosed. Having large asymmetric nevi was a significant risk factor for all sites and was strongest for the lower limbs (relative risk [RR], 3.38; 95% CI, 2.62-4.38) and weakest for the upper limbs (RR, 1.96; 95% CI, 1.22-3.17; P = .02 for heterogeneity). Mean lifetime number of sunbathing vacations was significantly associated with risk of trunk melanomas (RR, 1.14; 95% CI, 1.07-1.22) and lower limb melanomas (RR, 1.12; 95% CI, 1.05-1.19) but not upper limb melanomas (RR, 0.98; 95% CI, 0.88-1.09) and head and neck melanomas (RR, 0.87; 95% CI, 0.73-1.04; P = .006 for heterogeneity). Indoor tanning was associated only with trunk melanomas (RR for the highest tertile, 1.49; 95% CI, 1.16-1.92) and lower limb melanomas (RR for the highest tertile, 1.33; 95% CI, 1.00-1.76; P = .002 for heterogeneity). Skin color, hair color, small symmetric nevi, and history of sunburns were associated with risk of melanoma on all sites.

Conclusions and Relevance

These results appear to support the hypothesis of divergent pathways to melanoma and that recreational sun exposure and indoor tanning are associated with melanoma on the lower limbs, the most common site of melanoma in women. These findings appear to have important preventive implications.

Personal history of keratinocyte carcinoma is associated with reduced risk of death from invasive melanoma in men

BACKGROUND

Previous studies have found an increased risk for invasive cutaneous melanoma (CM) among those with a history of keratinocyte carcinoma (KC).

OBJECTIVE

The aim of this study was to evaluate the risk of CM death after KC.

METHODS

The study was based on the Health Professionals Follow-up Study. A Cox proportional hazards model was used to examine the hazard ratio (HR) of death due to CM associated with personal history of KC among the entire study population (primary analysis) and among participants with invasive CM (secondary analysis), respectively.

RESULTS

We documented a total of 908 participants with invasive CM over a total of 0.7 million person-years of follow-up. Among all participants, the risk for development of either lethal or nonlethal invasive CM increased for those with a history of KC. The risk for death due to melanoma based on KC history was not significantly increased, with an HR of 1.53 (95% confidence interval, 0.95-2.46). In the case-only analysis, those with a history of KC had a significantly lower risk for death due to melanoma than those with no such history (HR, 0.60; 95% confidence interval, 0.35-0.94).

LIMITATIONS

Because the population covered by the Health Professionals Follow-up Study consists exclusively of male health professionals, the results of this study may not be extended to the entire population.

CONCLUSION

Personal history of KC is associated with a decreased risk for melanoma-specific death among male patients with invasive CM.

Iris pigmented lesions as a marker of cutaneous melanoma risk: an Australian case-control study

BACKGROUND

Iris naevi and iris freckles have a frequency of 4% and 50% in the European population, respectively. They are associated with dysplastic naevi, but few studies have examined their link to cutaneous melanoma.

OBJECTIVES

To assess whether iris pigmented lesions are a predictive indicator for cutaneous melanoma.

METHODS

This is a melanoma case-control study of 1254 European-background Australians. Sun exposure and melanoma history, a saliva sample for DNA analysis and eye photographs taken with a digital camera were collected from 1117 participants. Iris images were assessed by up to four trained observers for the number of iris pigmented lesions. The data were analysed for correlations between iris pigmented lesions and melanoma history.

RESULTS

Case participants over the age of 40 had similar numbers of iris pigmented lesions to age matched controls (mean 5·7 vs. 5·2, P = 0·02), but in younger case and control participants there was a greater difference (mean 3·96 vs. 2·19, P = 0·004). A logistic regression adjusted for age, sex, skin, hair and eye colour, skin freckling and naevus count found that the presence of three or more iris pigmented lesions increases the melanoma risk 1·45-fold [95% confidence interval (CI) 1·07-1·95]. HERC2/OCA2 rs12913832 and IRF4 rs12203592 influenced both eye colour and the number of iris pigmented lesions. On the HERC2/OCA2 A/A and A/G genotype background there was an increasing proportion of blue eye colour when carrying the IRF4 T allele (P = 3 × 10^-4 ) and a higher number of iris pigmented lesions with the IRF4 T/T homozygote (P = 3 × 10^-9 ).

CONCLUSIONS

Iris pigmented lesion count provides additional predictive information for melanoma risk above that from conventional risk factors.

Cutaneous melanoma: From pathogenesis to therapy (Review)

In less than 10 years, melanoma treatment has been revolutionized with the approval of tyrosine kinase inhibitors and immune checkpoint inhibitors, which have been shown to have a significant impact on the prognosis of patients with melanoma. The early steps of this transformation have taken place in research laboratories. The mitogen‑activated protein kinase (MAPK) pathway, phosphoinositol‑3‑kinase (PI3K) pathway promote the development of melanoma through numerous genomic alterations on different components of these pathways. Moreover, melanoma cells deeply interact with the tumor microenvironment and the immune system. This knowledge has led to the identification of novel therapeutic targets and treatment strategies. In this review, the epidemiological features of cutaneous melanoma along with the biological mechanisms involved in its development and progression are summarized. The current state‑of‑the‑art of advanced stage melanoma treatment strategies and the currently available evidence of the use of predictive and prognostic biomarkers are also discussed.

Cutaneous melanoma primary site is linked to nevus density

There are at least two pathways driving cutaneous melanoma; one is linked to an inherent melanoma susceptibility to nevi development and the second to environmental cumulative ultraviolet light exposure. In this study, we examined the relation between nevus density, accrued sun damage and the site of primary melanoma excision. In a series of 888 consecutive cutaneous melanoma patients, melanomas appearing in skin areas with a high relative nevus density were most prominent in men, with an elevated nevus count, at sites without solar elastosis, but with an epidemiological history of previous sunburn. The present study associates melanoma development to sites with high nevus density. Our study supports more careful surveillance of body areas with increased nevus density in patients with high total body number of nevi, especially when they report a history of sunburns at these sites.

Melanoma Arising in a Melanocytic Nevus

The association of melanoma with a preexisting melanocytic nevus varies considerably between series, depending on whether the association is based on histological signs (4%-72%) or a clinically evident lesion (42%-85%). Histological association with a nevus correlates with favorable prognostic factors, whereas a clinical association correlates with unfavorable factors. In this review, we discuss the characteristics of nevus-associated melanoma from different perspectives: Whiteman's divergent pathway hypothesis for the development of cutaneous melanoma; and the factors involved in nevogenicity, including both the genetic and molecular factors involved in the development of the melanoma and its precursor lesions. Finally, a cumulative analysis of the 16 162 cases reported in the literature revealed that 29.8% of melanomas are histologically associated with a melanocytic nevus.

History of Keratinocyte Carcinoma and Risk of Melanoma: A Prospective Cohort Study

Background

The association between history of keratinocyte carcinoma (KC, also known as nonmelanoma skin cancer) and risk of developing invasive melanoma has not been assessed comprehensively using prospective data.

Methods

We followed 91 846 women in the Nurses' Health Study (NHS; 1984-2010), 114 918 women in the NHSII (1989-2011), and 48 946 men in the Health Professionals Follow-up Study (1986-2010) for diagnoses of KC and melanoma biennially. Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) of melanoma associated with history of KC, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). All statistical tests were two-sided.

Results

We documented 1949 melanomas, 38 842 BCCs, and 7462 SCCs over 6.4 million person-years of follow-up. After adjustment for other risk factors, a personal history of KC was associated with an increased risk of melanoma (meta-analysis HR = 2.22, 95% CI = 1.73 to 2.85). The association was more apparent among participants with a history of both BCC and SCC (HR = 3.40, 95% CI = 1.60 to 7.19) than among participants with a history of BCC only (HR = 2.20, 95% CI = 1.80 to 2.70) or SCC only (HR = 1.56, 95% CI = 0.98 to 2.46), and there was a strong risk-increasing trend associated with a higher number of reported KCs removed by surgery ( P trend < .001). In women, KC history was more strongly associated with head/neck melanomas (HR = 4.17, 95% CI = 2.77 to 6.27) than with trunk or limb melanomas (both HRs < 2.50, P heterogeneity = .04).

Conclusions

Our results provide novel insights for the relationship between KC history and risk of developing melanoma, which may be important for melanoma prevention.

Higher Nevus Count Exhibits a Distinct DNA Methylation Signature in Healthy Human Skin: Implications for Melanoma

High nevus count is the strongest risk factor for melanoma, and although gene variants have been discovered for both traits, epigenetic variation is unexplored. We investigated 322 healthy human skin DNA methylomes associated with total body nevi count, incorporating genetic and transcriptomic variation. DNA methylation changes were identified at genes involved in melanocyte biology, such as RAF1 (P = 1.2 × 10^-6) and CTC1 (region: P = 6.3 × 10^-4), and other genes including ARRDC1 (P = 3.1 × 10^-7). A subset exhibited coordinated methylation and transcription changes within the same biopsy. The total analysis was also enriched for melanoma-associated DNA methylation variation (P = 6.33 × 10^-6). In addition, we show that skin DNA methylation is associated in cis with known genome-wide association study single nucleotide polymorphisms for nevus count, at PLA2G6 (P = 1.7 × 10^-49) and NID1 (P = 6.4 × 10^-14), as well as melanoma risk, including in or near MC1R, MX2, and TERT/CLPTM1L (P < 1 × 10^-10). Our analysis using a uniquely large dataset comprising healthy skin DNA methylomes identified known and additional regulatory loci and pathways in nevi and melanoma biology. This integrative study improves our understanding of predisposition to nevi and their potential contribution to melanoma pathogenesis.

Ultraviolet Radiation Exposure and Its Impact on Skin Cancer Risk

OBJECTIVES

To review research and evidence-based resources on skin cancer prevention and early detection and their importance for oncology nurses.

DATA SOURCES

Journal articles, federal reports, cancer surveillance data, behavioral surveillance data.

CONCLUSION

Most cases of skin cancer are preventable. Survivors of many types of cancer are at increased risk of skin cancers.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses can play an important role in protecting their patients from future skin cancer morbidity and mortality.

Caffeine Intake, Coffee Consumption, and Risk of Cutaneous Malignant Melanoma

BACKGROUND

Caffeine has been shown to prevent ultraviolet radiation-induced carcinogenesis and to inhibit growth of melanoma cells in experimental studies. We evaluated the association among caffeine intake, coffee consumption, and melanoma risk among three large cohort studies.

METHODS

The analysis used data from 89,220 women in the Nurses' Health Study II (1991-2009), 74,666 women in the Nurses' Health Study (1980-2008), and 39,424 men in the Health Professionals Follow-up Study (1986-2008). We used Cox proportional hazards models to estimate the hazard ratios (HR) with 95% confidence intervals (CIs) of melanoma associated with dietary intakes.

RESULTS

We documented 2,254 melanoma cases over 4 million person-years of follow-up. After adjustment for other risk factors, higher total caffeine intake was associated with a lower risk of melanoma (≥393 mg/day vs. <60 mg/day: HR = 0.78, 95% CI = 0.64, 0.96; Ptrend = 0.048). The association was more apparent in women (≥393 mg/day vs. <60 mg/day: HR = 0.70, 95% CI = 0.58, 0.85; Ptrend = 0.001) than in men (HR = 0.94, 95% CI = 0.75, 1.2; Ptrend = 0.81), and more apparent for melanomas occurring on body sites with higher continuous sun exposure (head, neck, and extremities; ≥393 mg/day vs. <60 mg/day: HR = 0.71, 95% CI = 0.59, 0.86; Ptrend = 0.001) than for melanomas occurring on body sites with lower continuous sun exposure (trunk including shoulder, back, hip, abdomen, and chest; HR = 0.90, 95% CI = 0.70, 1.2; Ptrend = 0.60). This pattern of association was similar to that for caffeinated coffee consumption, whereas no association was found for decaffeinated coffee consumption and melanoma risk.

CONCLUSIONS

Increasing caffeine intake and caffeinated coffee consumption is associated with decreased risk of cutaneous malignant melanomas.

Association of nevus count with prevention attitudes and behaviors before melanoma diagnosis

Although melanoma risk factors are commonly known to healthcare professionals, the extent to which the at-risk public is either aware of these factors or perceives their risk accordingly has rarely been studied. We sought to investigate whether the presence of known melanoma risk factors, such as high total nevus and atypical nevus counts, was associated with increased prevention attitudes and behaviors, such as skin self-examinations and physician skin examinations. This was a retrospective study of 566 individuals recently diagnosed with melanoma in two large academic centers. Most prevention attitudes and behaviors did not vary on the basis of total nevi or atypical nevi counts. However, younger patients (<60 years) with many total nevi (>50) were more likely than those with fewer nevi (<20) to believe that they were at-risk for melanoma (42 vs. 23%; P<0.05), and more likely to state that they had been instructed on the signs of melanoma (36 vs. 21%; P<0.05). Patient and health provider recognition of the impact of nevus count on melanoma risk presents a unique and mostly untapped opportunity for earlier detection.

Association Between Indoor Tanning and Melanoma in Younger Men and Women

IMPORTANCE

In the United States and Minnesota, melanoma incidence is rising more steeply among women than men younger than 50 years. To our knowledge, no study has examined age- and sex-specific associations between indoor tanning and melanoma to determine if these trends could be due to greater indoor tanning use among younger women.

OBJECTIVE

To examine associations between indoor tanning and melanoma among men and women younger than 50 years.

DESIGN, SETTING, AND PARTICIPANTS

Population-based case-control study conducted in Minnesota of 681 patients (465 [68.3%] women) diagnosed as having melanoma between 2004 and 2007, and 654 controls (446 [68.2%] women), ages 25 to 49 years.

EXPOSURE

Indoor tanning, defined as any use, first age of use, and total sessions.

MAIN OUTCOMES AND MEASURES

Crude and adjusted odds ratios (ORs) and 95% CIs were calculated for melanoma in relation to indoor tanning exposure for men and women by diagnosis or reference age (<30, 30-39, 40-49 years). Sex-specific associations for indoor tanning and melanoma by anatomic site were examined.

RESULTS

Compared with women aged 40 to 49 years, women younger than 40 years initiated indoor tanning at a younger age (16 vs 25 years, P < .001) and reported more frequent indoor tanning (median number of sessions, 100 vs 40, P < .001). Women younger than 30 years were 6 times more likely to be in the case than the control group if they tanned indoors (crude OR, 6.0; 95% CI, 1.3-28.5). Odds ratios were also significantly elevated among women, ages 30 to 49 years (adjusted OR, 3.5; 95% CI, 1.2-9.7 for women 30-39 years; adjusted OR, 2.3; 95% CI, 1.4-3.6 for women 40-49 years); a dose response was observed among women regardless of age. Among men, results by age were inconsistent. The strongest OR for indoor tanning by anatomic site was for melanomas arising on the trunk of women (adjusted OR, 3.7; 95% CI, 1.9-7.2).

CONCLUSIONS AND RELEVANCE

Indoor tanning is a likely factor for the steeper increase in melanoma rates in the United States among younger women compared with men, given the timing of when women initiated indoor tanning relative to diagnosis. The melanoma epidemic can be expected to continue unless indoor tanning is restricted and reduced.

Association of Interferon Regulatory Factor-4 Polymorphism rs12203592 With Divergent Melanoma Pathways

BACKGROUND

Solar elastosis and neval remnants are histologic markers characteristic of divergent melanoma pathways linked to differences in age at onset, host phenotype, and sun exposure. However, the association between these pathway markers and newly identified low-penetrance melanoma susceptibility loci remains unknown.

METHODS

In the Genes, Environment and Melanoma (GEM) Study, 2103 Caucasian participants had first primary melanomas that underwent centralized pathology review. For 47 single-nucleotide polymorphisms (SNPs) previously identified as low-penetrant melanoma risk variants, we used multinomial logistic regression to compare melanoma with solar elastosis and melanoma with neval remnants simultaneously to melanoma with neither of these markers, excluding melanomas with both markers. All statistical tests were two-sided.

RESULTS

IRF4 rs12203592 was the only SNP to pass the false discovery threshold in baseline models adjusted for age, sex, and study center. rs12203592*T was associated positively with melanoma with solar elastosis (odds ratio [OR] = 1.47, 95% confidence interval [CI] = 1.18 to 1.82) and inversely with melanoma with neval remnants (OR = 0.65, 95% CI = 0.48 to 0.87) compared with melanoma with neither marker (P global = 3.78 x 10(-08)). Adjusting for phenotypic characteristics and total sun exposure hours did not materially affect rs12203592's associations. Distinct early- and late-onset age distributions were observed in patients with IRF4 rs12203592 [CC] and [TT] genotypes, respectively.

CONCLUSIONS

Our findings suggest a role of IRF4 rs12203592 in pathway-specific risk for melanoma development. We hypothesize that IRF4 rs12203592 could underlie in part the bimodal age distribution reported for melanoma and linked to the divergent pathways.

High nevus counts confer a favorable prognosis in melanoma patients

A high number of nevi is the most significant phenotypic risk factor for melanoma and is in part genetically determined. The number of nevi decreases from middle age onward but this senescence can be delayed in patients with melanoma. We investigated the effects of nevus number count on sentinel node status and melanoma survival in a large cohort of melanoma cases. Out of 2,184 melanoma cases, 684 (31.3%) had a high nevus count (>50). High nevus counts were associated with favorable prognostic factors such as lower Breslow thickness, less ulceration and lower mitotic rate, despite adjustment for age. Nevus count was not predictive of sentinel node status. The crude 5- and 10-year melanoma-specific survival rate was higher in melanomas cases with a high nevus count compared to those with a low nevus count (91.2 vs. 86.4% and 87.2 vs. 79%, respectively). The difference in survival remained significant after adjusting for all known melanoma prognostic factors (hazard ratio [HR] = 0.43, confidence interval [CI] = 0.21-0.89). The favorable prognostic value of a high nevus count was also seen within the positive sentinel node subgroup of patients (HR = 0.22, CI = 0.08-0.60). High nevus count is associated with a better melanoma survival, even in the subgroup of patients with positive sentinel lymph node. This suggests a different biological behavior of melanoma tumors in patients with an excess of nevi.

Melanoma density and relationship with the distribution of melanocytic naevi in an Italian population: a GIPMe study--the Italian multidisciplinary group on melanoma

The most frequent site for melanoma is the back in men and the lower limbs in women, where intermittent sun exposure has been reported to be an environmental agent, although studies on age-specific incidence have suggested that melanoma in chronically sun-exposed areas, such as the face, increases with age. To identify the preferential development of melanoma in chronically or intermittently sun-exposed areas and the relationship between body site distribution and parameters such as sex, age, distribution of melanocytic naevi, atypical naevi and actinic keratoses, a prospective epidemiological multicentre study was carried out on all the consecutive melanoma cases diagnosed in a 2-year period from 27 Italian GIPMe centres (GIPMe: the Italian Multidisciplinary Group on Melanoma). Both the relative density of melanoma (RDM), defined as the ratio between observed and expected melanoma for a specific body site, and the average nevi density were identified. The most common melanoma site was the back, a factor that was not affected by either age or sex, even if men had higher density values. Statistically significant higher RDM values were observed in women aged more than 50 years for leg lesions and in the anterior thighs for young women (<50 years), whereas the lowest values were observed in the posterior thighs in women of any age. Facial RDM was statistically significantly higher than expected in both male and female patients more than 50 years of age. Melanoma was associated with a significantly higher atypical naevi density only for the back, chest and thighs. Indeed, facial melanoma was related to the presence of more than four actinic keratoses and not naevi density. To the best of our knowledge, the RDM method was applied for the first time together with naevus density calculation to obtain these data, which strongly substantiate the 'divergent pathway' hypothesis for the development of melanoma, but not find a direct correlation between melanoma and nevi for each anatomical site.

Differences in clinicopathological features and distribution of risk factors in Italian melanoma patients

BACKGROUND

No studies are available in the literature on the distribution of different melanoma features and risk factors in the Italian geographical areas.

OBJECTIVE

To identify the differences in clinical-pathological features of melanoma, the distribution of risk factors and sun exposure in various Italian macro-areas.

METHODS

Multicentric-observational study involving 1,472 melanoma cases (713 north, 345 centre, 414 south) from 26 referral centres belonging to the Italian Multidisciplinary Group for Melanoma.

RESULTS

Melanoma patients in northern regions are younger, with thinner melanoma, multiple primaries, lower-intermediate phototype and higher counts of naevi with respect to southern patients; detection of a primary was mostly connected with a physician examination, while relatives were more involved in the south. Northern patients reported a more frequent use of sunbeds and occurrence of sunburns before melanoma despite sunscreen use and a lower sun exposure during the central hours of the day.

CONCLUSIONS

The understanding of differences in risk factors distribution could represent the basis for tailored prevention programmes.

Development of a melanoma risk prediction model incorporating MC1R genotype and indoor tanning exposure: impact of mole phenotype on model performance

Background

Identifying individuals at increased risk for melanoma could potentially improve public health through targeted surveillance and early detection. Studies have separately demonstrated significant associations between melanoma risk, melanocortin receptor (MC1R) polymorphisms, and indoor ultraviolet light (UV) exposure. Existing melanoma risk prediction models do not include these factors; therefore, we investigated their potential to improve the performance of a risk model.

Methods

Using 875 melanoma cases and 765 controls from the population-based Minnesota Skin Health Study we compared the predictive ability of a clinical melanoma risk model (Model A) to an enhanced model (Model F) using receiver operating characteristic (ROC) curves. Model A used self-reported conventional risk factors including mole phenotype categorized as “none”, “few”, “some” or “many” moles. Model F added MC1R genotype and measures of indoor and outdoor UV exposure to Model A. We also assessed the predictive ability of these models in subgroups stratified by mole phenotype (e.g. nevus-resistant (“none” and “few” moles) and nevus-prone (“some” and “many” moles)).

Results

Model A (the reference model) yielded an area under the ROC curve (AUC) of 0.72 (95% CI = 0.69, 0.74). Model F was improved with an AUC = 0.74 (95% CI = 0.71–0.76, p<0.01). We also observed substantial variations in the AUCs of Models A & F when examined in the nevus-prone and nevus-resistant subgroups.

Conclusions

These results demonstrate that adding genotypic information and environmental exposure data can increase the predictive ability of a clinical melanoma risk model, especially among nevus-prone individuals.

Emerging trends in the epidemiology of melanoma

Cutaneous melanoma (CM) is one of the most rapidly growing cancers worldwide, with a consistent increase in incidence among white populations over the past four decades. Despite the early detection of primarily thin melanomas and the improved survival rates observed in several countries, the rate of thick melanomas has remained constant or continues to increase, especially in the older age group. Current considerations in the epidemiology of melanoma focus on the observed survival benefit of females vs. males, the contributing role of indoor tanning in melanoma risk and the diverse effect of sun exposure in the development of different types of melanoma with respect to their clinical and mutational profile. Certain well-known risk factors, such as skin, hair and eye pigmentation and melanocytic naevi have been validated in large-scale association studies, while additional lifestyle factors and iatrogenic exposures, such as immunosuppressive agents and nonsteroidal anti-inflammatory drugs are being investigated. In addition, genome-wide association studies have revealed genetic loci that underlie the genetic susceptibility of melanoma, some of which are related to known risk factors. Recently, an interesting association of melanoma with Parkinson disease has been noted, with a higher than expected frequency of melanoma in patients with Parkinson disease and vice versa. This review article provides an update in the epidemiology of cutaneous melanoma and discusses recent developments in the field.

Site-specific determinants of cutaneous melanoma: a case-case comparison of patients with tumors arising on the head or trunk

BACKGROUND

Cutaneous melanomas have been hypothesized to arise through different pathways according to phenotype, body site, and sun exposure. To further test this hypothesis, we explored associations between phenotype and melanoma at different sites using a case-case comparative approach.

METHODS

Melanoma patients (n = 762) aged 18 to 79 years and diagnosed from 2007 to 2010 were ascertained from pathology laboratories in Brisbane, Australia. Patients reported phenotypic information and a dermatologist counted melanocytic nevi and solar keratoses. We compared data for patients with trunk melanoma (n = 541, the reference group), head/neck melanoma (n = 122), or lentigo maligna melanoma (LMM) of the head/neck (n = 69). ORs and 95% confidence intervals were calculated using classical or polytomous logistic regression models.

RESULTS

Compared with trunk melanoma patients, those with head/neck melanoma were significantly less likely to have high nevus counts (≥135: OR = 0.27; Ptrend = 0.0004). Associations between category of nevus count and LMM head/neck were weaker and significantly different (≥135: OR = 1.09; Ptrend = 0.69; Phomogeneity = 0.02). Patients with head/neck melanoma were more likely than those with truncal melanoma to have high solar keratosis counts (≥7: OR = 1.78, Ptrend = 0.04). Again, associations with LMM head/neck were weaker, albeit not significantly different (≥7: OR = 1.61; Ptrend = 0.42; Phomogeneity = 0.86).

CONCLUSION

Trunk melanomas are more strongly associated with nevus counts than head/neck melanomas, but are less strongly associated with number of solar keratoses, a marker of chronic sun exposure.

IMPACT

These findings underscore the notion that melanomas on the trunk typically arise through a causal pathway associated with nevus propensity, whereas melanomas on the head/neck arise through a pathway associated with cumulative sun exposure.

Melanoma risk loci as determinants of melanoma recurrence and survival

Background

Steadily high melanoma mortality rates urge for the availability of novel biomarkers with a more personalized ability to predict melanoma clinical outcomes. Germline risk variants are promising candidates for this purpose; however, their prognostic potential in melanoma has never been systematically tested.

Methods

We examined the effect of 108 melanoma susceptibility single nucleotide polymorphisms (SNPs), associated in recent GWAS with melanoma and melanoma-related phenotypes, on recurrence-free survival (RFS) and overall survival (OS), in 891 prospectively accrued melanoma patients. Cox proportional hazards models (Cox PH) were used to test the associations between 108 melanoma risk SNPs and RFS and OS adjusted by age at diagnosis, gender, tumor stage, histological subtype and other primary tumor characteristics.

Results

We identified significant associations for rs7538876 (RCC2) with RFS (HR = 1.48, 95% CI = 1.20-1.83, p = 0.0005) and rs9960018 (DLGAP1) with both RFS and OS (HR = 1.43, 95% CI = 1.07-1.91, p = 0.01, HR = 1.52, 95% CI = 1.09-2.12, p = 0.01, respectively) using multivariable Cox PH models. In addition, we developed a logistic regression model that incorporates rs7538876, rs9960018, primary tumor histological type and stage at diagnosis that has an improved discriminatory ability to classify 3-year recurrence (AUC = 82%) compared to histological type and stage alone (AUC = 78%).

Conclusions

We identified associations between melanoma risk variants and melanoma outcomes. The significant associations observed for rs7538876 and rs9960018 suggest a biological implication of these loci in melanoma progression. The observed predictive patterns of associated variants with clinical end-points suggest for the first time the potential for utilization of genetic risk markers in melanoma prognostication.

Risk factors for limb melanomas compared with trunk melanomas in Queensland

The objective of this study was to investigate the risk factors for melanoma on the arms and legs in comparison with well-known risk factors for trunk melanoma. The study was a population-based case-control study of 77 individuals with limb (25 arm; 52 leg) and 86 with trunk melanoma, who were representative of all the individuals newly-diagnosed with primary limb melanomas in Queensland during 1979-1980 and 232 controls. A single physician interviewed and examined all individuals and assessed complexion type, sun exposure history and other potential risk factors and clinical features. After multivariate analysis, the strongest risk factor for both limb and trunk melanomas was the presence of more than 10 naevi on the arm (odds ratio limb melanoma=41.4, 95% confidence interval 10.4-164), though on histology, a preexisting naevus was more strongly associated with trunk than limb melanoma (P<0.004). Associations with blonde/light brown hair, propensity to freckle and sunburn were similar for melanoma on both sites. A lifetime history of painful sunburns significantly raised the risk of trunk but not limb melanoma, whereas solar keratoses on the arm or face were more strongly associated with limb than with trunk melanoma (marginally significant, P(homogeneity)=0.056). High ambient solar ultraviolet radiation in adolescence was also a stronger risk factor for limb than for trunk melanoma. In conclusion, this population-based investigation into specific differences in causes of limb versus melanomas of other sites suggests that the risk factor profile is intermediate between the profiles for head/neck melanoma (mostly cumulative sun damage) and for trunk melanomas (most strongly related to naevi).

Characterization of nonacral melanoma patients without typical risk factors

A divergent pathway model to cutaneous melanoma is commonly accepted: sun sensitivity/chronic sun exposure and melanocytic instability. Although this dual model explains the development of most melanomas, clinical experience suggests other possible routes. The aim of this study was to explore the characteristics of patients who do not fit with these two pathways. We selected 818 patients with nonacral cutaneous melanoma and defined three groups: nevus-prone individuals, sun-sensitive individuals, and non-nevus-prone and non-sun-sensitive individuals. This group included patients without identifiable melanoma risk factors and comprised 52 patients (5.5% of the overall nonacral melanoma population). These patients were more frequently women, were more likely to present melanoma at a very young age (13.5% before 25 years), to have less frequent personal history of melanoma and remnants of pre-existing nevi, and to present tumors on the trunk and legs. We have identified a group of patients with fewer risk factors for melanoma that needs further studies to increase our understanding of melanoma development.

A prospective, population-based study of 40,000 women regarding host factors, UV exposure and sunbed use in relation to risk and anatomic site of cutaneous melanoma

Prospective cohort studies about cutaneous melanoma (CM) risk are still few. Host factor- and UVR exposure data were collected prospectively by questionnaire in this population-based cohort study including 40,000 Swedish born women, aged 25-64 years at enrolment (1990). Risk for CM (Cox regression and Stepwise Cox regression [SCR], hazard ratios [HRs] with 95% Confidence Intervals [CI]) in relation to risk factors, age groups (older or younger than 40 years) and primary site, were analyzed. In 29,520 women with complete follow-up through 2007, 155 invasive and 60 in situ CM were recorded. High numbers of nevi (HR, 2.9; 95% CI, 1.7-5.0) and heredity (HR, 3.7; 95% CI, 2.0-6.8) were associated with risk for CM. SCR analysis added red hair as a risk factor. Sunbed use >10 times/year increased risk for women <40 years (HR, 2.5; 95% CI, 1.0-6.2) and a trend for risk associated with sunbathing vacations (HR, 1.4; 95% CI, 1.0-2.0) was shown for women >40 years. Trunk melanoma showed correlations with high numbers of nevi (HR, 3.0; 95% CI, 1.2-7.3) and heredity (HR, 3.2; 95% CI, 1.1-9.4). Head/neck site was correlated to sunbathing vacations (HR, 2.5; 95% CI, 1.2-5.3) and heredity (HR, 7.6; 95% CI, 1.8-31.8). Our study supports divergent etiologic pathways to CM, with high numbers of nevi correlated to increased risk for trunk CM. Furthermore, it confirms that high numbers of nevi, red hair and heredity for CM are the most important risk factors and frequent sunbed use might be a risk factor for younger women.

The melanomas: a synthesis of epidemiological, clinical, histopathological, genetic, and biological aspects, supporting distinct subtypes, causal pathways, and cells of origin

Converging lines of evidence from varied scientific disciplines suggest that cutaneous melanomas comprise biologically distinct subtypes that arise through multiple causal pathways. Understanding the respective relationships of each subtype with etiologic factors such as UV radiation and constitutional factors is the first necessary step toward developing refined prevention strategies for the specific forms of melanoma. Furthermore, classifying this disease precisely into biologically distinct subtypes is the key to developing mechanism-based treatments, as highlighted by recent discoveries. In this review, we outline the historical developments that underpin our understanding of melanoma heterogeneity, and we do this from the perspectives of clinical presentation, histopathology, epidemiology, molecular genetics, and developmental biology. We integrate the evidence from these separate trajectories to catalog the emerging major categories of melanomas and conclude with important unanswered questions relating to the development of melanoma and its cells of origin.

Pathways to melanoma

Melanoma is one of the most aggressive and yet poorly understood of human malignancies. Advances in genomics has allowed a more nuanced understanding of the disease, moving beyond the traditional dysplastic nevus-to-melanoma model and identifying multiple divergent oncogenic pathways leading to melanoma. An understanding of the molecular mechanisms driving melanoma has opened the doors for the development of targeted therapeutic approaches. As we enter the era of personalized medicine, it will be critical for clinicians to both appreciate and be able to determine the molecular profile of their patients' melanoma because this profile will guide risk stratification, genetic counseling, and treatment customization. A review of the divergent pathways of melanoma development is presented here, with a particular emphasis on recently identified mutations, and their implications for patient care.

The association between Parkinson's disease and melanoma

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a loss of melanin-positive, dopaminergic neurons in the substantia nigra. Although there is convincing epidemiologic evidence of a negative association between PD and most cancers, a notable exception to this is that melanoma, a malignant tumor of melanin-producing cells in skin, occurs with higher-than-expected frequency among subjects with PD and that melanoma patients are more likely to have PD. A clear biological explanation for this epidemiological observation is lacking. Here, we present a comprehensive review of published literature exploring the association between PD and melanoma. On the basis of published findings, we conclude that (i) changes in pigmentation including melanin synthesis and/or melanin synthesis enzymes, such as tyrosinase and tyrosine hydroxylase, play important roles in altered vulnerability for both PD and melanoma; (ii) changes of PD-related genes such as Parkin, LRRK2 and α-synuclein may increase the risk of melanoma; (iii) changes in some low-penetrance genes such as cytochrome p450 debrisoquine hydroxylase locus, glutathione S-transferase M1 and vitamin D receptor could increase the risk for both PD and melanoma and (iv) impaired autophagy in both PD and melanoma could also explain the association between PD and melanoma. Future studies are required to address whether altered pigmentation, PD- or melanoma-related gene changes and/or changes in autophagy function induce oncogenesis or apoptosis. From a clinical point of view, early diagnosis of melanoma in PD patients is critical and can be enhanced by periodic dermatological surveillance, including skin biopsies.

The human health effects of ozone depletion and interactions with climate change

Depletion of the stratospheric ozone layer has led to increased solar UV-B radiation (280-315 nm) at the surface of the Earth. This change is likely to have had an impact on human exposure to UV-B radiation with consequential detrimental and beneficial effects on health, although behavioural changes in society over the past 60 years or so with regard to sun exposure are of considerable importance. The present report concentrates on information published since our previous report in 2007. The adverse effects of UV radiation are primarily on the eye and the skin. While solar UV radiation is a recognised risk factor for some types of cataract and for pterygium, the evidence is less strong, although increasing, for ocular melanoma, and is equivocal at present for age-related macular degeneration. For the skin, the most common harmful outcome is skin cancer, including melanoma and the non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma. The incidence of all three of these tumours has risen significantly over the past five decades, particularly in people with fair skin, and is projected to continue to increase, thus posing a significant world-wide health burden. Overexposure to the sun is the major identified environmental risk factor in skin cancer, in association with various genetic risk factors and immune effects. Suppression of some aspects of immunity follows exposure to UV radiation and the consequences of this modulation for the immune control of infectious diseases, for vaccination and for tumours, are additional concerns. In a common sun allergy (polymorphic light eruption), there is an imbalance in the immune response to UV radiation, resulting in a sun-evoked rash. The major health benefit of exposure to solar UV-B radiation is the production of vitamin D. Vitamin D plays a crucial role in bone metabolism and is also implicated in protection against a wide range of diseases. Although there is some evidence supporting protective effects for a range of internal cancers, this is not yet conclusive, but strongest for colorectal cancer, at present. A role for vitamin D in protection against several autoimmune diseases has been studied, with the most convincing results to date for multiple sclerosis. Vitamin D is starting to be assessed for its protective properties against several infectious and coronary diseases. Current methods for protecting the eye and the skin from the adverse effects of solar UV radiation are evaluated, including seeking shade, wearing protective clothing and sunglasses, and using sunscreens. Newer possibilities are considered such as creams that repair UV-induced DNA damage, and substances applied topically to the skin or eaten in the diet that protect against some of the detrimental effects of sun exposure. It is difficult to provide easily understandable public health messages regarding "safe" sun exposure, so that the positive effects of vitamin D production are balanced against the negative effects of excessive exposure. The international response to ozone depletion has included the development and deployment of replacement technologies and chemicals. To date, limited evidence suggests that substitutes for the ozone-depleting substances do not have significant effects on human health. In addition to stratospheric ozone depletion, climate change is predicted to affect human health, and potential interactions between these two parameters are considered. These include altering the risk of developing skin tumours, infectious diseases and various skin diseases, in addition to altering the efficiency by which pathogenic microorganisms are inactivated in the environment.

Biologic markers of sun exposure and melanoma risk in women: pooled case-control analysis

A model has been proposed whereby melanomas arise through two distinct pathways dependent on the relative influence of host susceptibility and sun exposure. Such pathways may explain site-specific patterns of melanoma occurrence. To explore this model, we investigated the relationship between melanoma risk and general markers of acute (recalled sunburns) and chronic (prevalent solar keratoses) sun exposure, stratified by anatomic site and host phenotype. Our working hypothesis was that head and neck melanomas have stronger associations with solar keratoses and weaker associations with sunburn than trunk melanomas. We conducted a collaborative analysis using original data from women subjects of 11 case-control studies of melanoma (2,575 cases, 3,241 controls). We adjusted for potential confounding effects of sunlamp use and sunbathing. The magnitude of sunburn associations did not differ significantly by melanoma site, nevus count or histologic subtype of melanoma. Across all sites, relative risk of melanoma increased with an increasing number of reported lifetime "painful" sunburns, lifetime "severe" sunburns and "severe" sunburns in youth (p(trend) < 0.001), with pooled odds ratios (pORs) for the highest category of sunburns versus no sunburns of 3.22 [95% confidence interval (CI) 2.04-5.09] for lifetime "painful" sunburns, 2.10 (95%CI 1.30-3.38) for lifetime "severe" sunburns and 2.43 (95%CI 1.61-3.65) for "severe" sunburns in youth. Solar keratoses strongly increased the risk of head and neck melanoma (pOR 4.91, 95%CI 2.10-11.46), but data were insufficient to assess risk for other sites. Reported sunburn is strongly associated with melanoma on all major body sites.

Estimating the attributable fraction for melanoma: a meta-analysis of pigmentary characteristics and freckling

Epidemiologic research has demonstrated convincingly that certain pigmentary characteristics are associated with increased relative risks of melanoma; however there has been no comprehensive review to rank these characteristics in order of their importance on a population level. We conducted a systematic review of the literature and meta-analysis to quantify the contribution of pigmentary characteristics to melanoma, estimated by the population-attributable fraction (PAF). Eligible studies were those that permitted quantitative assessment of the association between histologically confirmed melanoma and hair colour, eye colour, skin phototype and presence of freckling; we identified 66 such studies using citation databases, followed by manual review of retrieved references. We calculated summary relative risks using weighted averages of the log RR, taking into account random effects, and used these to estimate the PAF. The pooled RRs for pigmentary characteristics were: 2.64 for red/red-blond, 2.0 for blond and 1.46 for light brown hair colour (vs. dark); 1.57 for blue/blue-grey and 1.51 for green/grey/hazel eye colour (vs. dark); 2.27, 1.99 and 1.35 for skin phototypes I, II and III respectively (vs. IV); and 1.99 for presence of freckling. The highest PAFs were observed for skin phototypes 1/II (0.27), presence of freckling (0.23), and blond hair colour (0.23). For eye colour, the PAF for blue/blue-grey eye colour was higher than for green/grey/hazel eye colour (0.18 vs. 0.13). The PAF of melanoma associated with red hair colour was 0.10. These estimates of melanoma burden attributable to pigmentary characteristics provide a basis for designing prevention strategies for melanoma.