The Effect of Sunscreen on Melanoma Risk

Review of the comparative pathological and immunohistochemical features of human and canine cutaneous melanocytic neoplasms

Melanocytic neoplasms originate from melanocytes and melanoma, the malignant form, is a common canine neoplasm and the most aggressive human skin cancer. Despite many similarities between these neoplasms in both species, only a limited number of studies have approached these entities in a comparative manner. Therefore, this review compares benign and malignant melanocytic neoplasms in dogs and humans, exclusively those arising in the haired skin, with regard to their clinicopathological, immunohistochemical and molecular aspects. Shared features include spontaneous occurrence, macroscopic features and microscopic findings when comparing human skin melanoma in the advanced/invasive stage and canine cutaneous melanoma, immunohistochemical markers and several histopathological prognostic factors. Differences include the apparent absence of active mutations in the BRAF gene in canine cutaneous melanoma and less aggressive clinical behaviour in dogs than in humans. Further studies are required to elucidate the aetiology and genetic development pathways of canine cutaneous melanocytic neoplasms. Evaluation of the applicability of histopathological prognostic parameters commonly used in humans for dogs are also needed. The similarities between the species and the recent findings regarding genetic mutations in canine cutaneous melanomas suggest the potential utility of dogs as a natural model for human melanomas that are not related to ultraviolet radiation.

Skin cancer prevention behaviors, beliefs, distress, and worry among hispanics in Florida and Puerto Rico

BACKGROUND

Incidence of skin cancer has been increasing among U.S. Hispanics, who often are diagnosed with larger lesions and at later stage disease. Behaviors to decrease exposure to ultraviolet radiation can reduce risk of skin cancer. We describe skin cancer prevention behaviors and psychosocial variables among Hispanic participants recruited into a skin cancer prevention trial.

METHODS

Self-reported Hispanic participants from eight primary care clinics in Tampa, Florida and Ponce, Puerto Rico were recruited into a randomized controlled prevention trial. Information on demographics, sun-related behaviors, and psychosocial variables were collected before intervention materials were provided. Multivariable regression models were used to compare baseline sun-related behaviors and psychosocial variables across groups defined by geographic location and language preference.

RESULTS

Participants reported low levels of intentional outdoor tanning, weekday and weekend sun exposure, and very low levels of indoor tanning. However, only a minority of participants practiced sun-protective behaviors often or always, and about 30% experienced a sunburn in the past year. Participants had low levels of recent worry and concern about skin cancer, modest levels of perceived risk and severity, and high levels of response efficacy and self-efficacy. When comparing across groups defined by geographic location and language preference, English-preferring Tampa residents (hereafter referred to as Tampeños) had the highest proportion who were sunburned (35.9%) and tended toward more risky behavior but also had higher protective behavior than did Spanish-preferring Tampeños or Puerto Ricans. Spanish-preferring Puerto Ricans had higher recent concern about skin cancer, comparative chance of getting skin cancer, and response efficacy compared to either English- or Spanish-preferring Tampeños. Spanish-preferring Tampeños had the highest levels of familism and recent distress about skin cancer.

CONCLUSIONS

Our results mirror previous observations of low levels of sun-protective behavior among U.S. Hispanics compelling the need for culturally appropriate and translated awareness campaigns targeted to this population. Because Hispanics in Tampa and Puerto Rico reported modest levels of perceived risk and severity, and high levels of response efficacy and self-efficacy, interventions aiming to improve skin cancer prevention activities that are anchored in Protection Motivation Theory may be particularly effective in this population subgroup.

Retention and Evaluation of Precision and Generic Prevention Materials for Melanoma: A Qualitative Study Comparing Young Adults and Adults

A randomized trial was conducted to examine whether providing precision prevention materials incorporating melanocortin-1 receptor genetic risk information would increase intention to practice melanoma preventive behaviors. Here, we determine retention/evaluation of prevention materials for adolescent and young adults (AYA) 18 to 39 years old versus adults aged 40+ at 6 and 12 months as an a priori adjunct analysis to the primary research question. Using qualitative methodology, open-ended questions probing most important information from prevention materials and additional comments were collected at 6 and 12 months after baseline. Descriptive statistics were performed on demographic/self-reported characteristics. Two independent researchers applied qualitative thematic content analysis to identify major themes in open-ended questions. Of the 1,134 participants randomized, 906 completed at least one of the follow-up surveys and contributed to analyses of intervention efficacy. Five major thematic categories emerged from the open-ended response data: (i) tips and tricks for sun protection; (ii) cancer prevention; (iii) risk factors and genetics; (iv) general information; and (v) intervention comments. Across all ages, the most important information retained were sun protection techniques in the generic prevention materials group and identifying the importance of genetic risk factors/implementing lifestyle behavior changes in the precision prevention materials group. For additional comments, AYA participants in the generic prevention materials group preferred more scientific information including statistics and citations for references while adults were more likely to state they already knew cancer prevention techniques. Results provide unique qualitative evaluation of AYA versus adult retention of prevention materials for melanoma that enhance quantitative findings.

PREVENTION RELEVANCE

It is important to evaluate information within groups defined by periods of the life trajectory, e.g., AYA and adults, to best inform preferences, knowledge, and motivation for behavior change. By assessing retention, evidence-based interventions can be designed to better support public health messaging and encourage positive health behaviors.

A Randomized Trial of Precision Prevention Materials to Improve Primary and Secondary Melanoma Prevention Activities among Individuals with Limited Melanoma Risk Phenotypes

Simple Summary

Inherited genetic variation at the MC1R gene is associated with increased risk of melanoma among non-Hispanic whites (NHWs), especially among those with skin and pigmentation characteristics that are associated with average to lower melanoma risk, for whom MC1R genetic testing may reveal unrecognized melanoma risk. We conducted a randomized trial to examine whether providing MC1R genetic risk information together with precision prevention materials would increase primary and secondary melanoma preventive behaviors compared to providing generic prevention materials only. We found that among participants with MC1R variants associated with higher risk of melanoma, the intervention increased shade-seeking or using an umbrella, increased wearing sleeved shirts, and decreased sunburns among their young children. We conclude that MC1R genetic testing and precision prevention materials may increase the practice of some sun-protective behaviors.

Abstract

Inherited variation at MC1R is associated with elevated melanoma risk among non-Hispanic whites (NHWs). MC1R genetic testing may unmask previously unrecognized disease risk, especially among individuals with few melanoma phenotypic risk factors. We recruited NHW individuals with limited phenotypic risk factors from two primary care clinics in west-central Florida. Participants (n = 1134) were randomized within MC1R genotype risk group (average/higher) to receive mailed precision prevention (i.e., intervention) or generic prevention materials. Participants reported hours of weekday and weekend sun exposure, frequency of intentional outdoor tanning and sun protection behaviors, number of sunburns, indoor tanning episodes, and skin examinations at baseline, and after 6 and 12 months. Among MC1R higher-risk participants, the intervention increased the likelihood of often or always wearing a shirt with sleeves (OR = 1.49, p = 0.03) and seeking shade or using an umbrella (OR = 1.42, p = 0.046), and it decreased the number of sunburns among their young children (β = −0.13, p = 0.03). Intervention effects were not noted among MC1R average-risk participants. Moderation analyses identified intervention effects within subgroups in average-risk and higher-risk participants. Precision prevention information conveying MC1R testing results can increase the practice of some sun protection behaviors among at-risk individuals with limited melanoma risk phenotypes and may provide a cross-generational tool to counteract increasing incidence of melanoma.

Pharmacologic manipulation of skin pigmentation

Skin complexion is among the most recognizable phenotypes between individuals and is mainly determined by the amount and type of melanin pigment deposited in the epidermis. Persons with dark skin complexion have more of a brown/black pigment known as eumelanin in their epidermis whereas those with fair skin complexions have less. Epidermal eumelanin acts as a natural sunblock by preventing incoming UV photons from penetrating into the skin and therefore protects against UV mutagenesis. By understanding the signaling pathways and regulation of pigmentation, strategies can be developed to manipulate skin pigmentation to improve UV resistance and to diminish skin cancer risk.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Non-use of sunscreen among adults and the elderly in southern Brazil

Background

One of the main prevention methods against skin cancer is the use of sunscreen; however, incidence of this disease has not declined despite prevention campaigns.

Objective

Investigate the prevalence of non-use of sunscreen and its associated factors.

Method

A population-based cross-sectional study with individuals aged 18 years or over living in the urban area. Conducted between April and July of 2016. Participants were interviewed about socioeconomic, demographic, and behavioral questions. Non-use of sunscreen was considered as the outcome. For multivariate analysis, Poisson regression with robust adjustment for variance was used.

Results

Among the 1300 participants, prevalence of non-use of sunscreen was 38.2% (95% CI: 34.6–41.8). The variables independently associated with the outcome were male sex, older age, brown or black skin color, lower income, fewer years of education, no physical activity in leisure time, no medical consultations in the last year, and self-perception of health as regular or poor.

Study limitations

The prevalence may be underestimated by reports of more use of sunscreen than actually used, which could increase the figure in the outcome.

Conclusion

It was estimated that about four out of ten adults and elderly do not use sunscreen in this sample. Prevention strategies are needed to advance health policy and ensure that sun protection options are easily accessible.

Malignant melanoma clinically mimicking pyogenic granuloma: comparison of clinical evaluation and histopathology

Amelanotic melanomas (AMMs) account for a small proportion of all melanomas. They pose a risk of delayed diagnosis and, consequently, poor prognosis. AMMs may atypically present as a pyogenic granuloma-like lesion. This study sought to investigate the prevalence and clinical and histological features of AMM masquerading as pyogenic granuloma. The database of a tertiary medical center was screened for all patients pathologically diagnosed with melanoma in 2005-2016. Those with a suspected primary (i.e. pre-excision) clinical diagnosis of pyogenic granuloma were identified, and their demographic, clinical, histologic, and outcome data were collected from the medical files. Of 2038 patients diagnosed with melanoma, 10 (∼0.5%) had a pyogenic granuloma-like AMM. The mean±SD age at lesion presentation was 56±18.9 years and the mean time from lesion appearance to diagnosis was 91.5±117.1 months. Nine tumors were located on the skin surface, and one on the oral mucosa. The mean lesion size was 19.6±14.1 mm and the mean Breslow's depth was 6.47±3.1 mm; all tumors presented in the vertical growth phase. Seven (70%) patients had lymph node involvement or metastasis at diagnosis. Two patients died of the disease within 1 year of diagnosis. Given the potential lethality of AMM and the benign nature of pyogenic granuloma, clinician recognition of pyogenic granuloma-like AMMs is crucial. In the presence of a pyogenic granuloma-like lesion, findings of older patient age and large tumor size should raise the index of suspicion and prompt a biopsy study, thereby ensuring early and accurate treatment.

UVA1 impairs the repair of UVB-induced DNA damage in normal human melanocytes

The exact correlation between melanoma and sun-light is still a controversially debated issue. Although natural sunlight contains various ratios of UVA and UVB, most investigators so far focused on the effects of single solar wavebands and neglected possible interactions. Therefore, in this study primary human melanocytes of three donors were simultaneously exposed to physiologic doses of UVA1 and UVB. Effects on apoptosis were analysed using annexin V assays and cell death ELISAs, and effects on DNA damage were investigated using southwestern slot blots. While UVA1 did not influence UVB-induced apoptosis, UVA1 impaired the repair of UVB-induced cyclobutane pyrimidine dimers (CPD) as the amount of CPD was 1.8 times higher in UVA1 + UVB than in UVB only exposed melanocytes six hours after irradiation. We conclude that UVA1 might contribute to melanomagenesis as it partially inhibits the repair of UVB-induced CPD in human melanocytes while it does not affect UVB-mediated apoptosis.

Sun protection for preventing basal cell and squamous cell skin cancers

BACKGROUND

'Keratinocyte cancer' is now the preferred term for the most commonly identified skin cancers basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), which were previously commonly categorised as non-melanoma skin cancers (NMSC). Keratinocyte cancer (KC) represents about 95% of malignant skin tumours. Lifestyle changes have led to increased exposure to the sun, which has, in turn, led to a significant increase of new cases of KC, with a worldwide annual incidence of between 3% and 8%. The successful use of preventive measures could mean a significant reduction in the resources used by health systems, compared with the high cost of the treatment of these conditions. At present, there is no information about the quality of the evidence for the use of these sun protection strategies with an assessment of their benefits and risks.

OBJECTIVES

To assess the effects of sun protection strategies (i.e. sunscreen and barrier methods) for preventing keratinocyte cancer (that is, basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) of the skin) in the general population.

SEARCH METHODS

We searched the following databases up to May 2016: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We also searched five trial registries and the bibliographies of included studies for further references to relevant trials.

SELECTION CRITERIA

We included randomised controlled clinical trials (RCTs) of preventive strategies for keratinocyte cancer, such as physical barriers and sunscreens, in the general population (children and adults), which may provide information about benefits and adverse events related to the use of solar protection measures. We did not include trials focused on educational strategies to prevent KC or preventive strategies in high-risk groups. Our prespecified primary outcomes were BCC or cSCC confirmed clinically or by histopathology at any follow-up and adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for eligibility using Early Review Organizing Software (EROS). Similarly, two review authors independently used predesigned data collection forms to extract information from the original study reports about the participants, methods of randomisation, blinding, comparisons of interest, number of participants originally randomised by arm, follow-up losses, and outcomes, and they assessed the risk of bias. We resolved any disagreement by consulting a third author and contacted trial investigators of identified trials to obtain additional information. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included one RCT (factorial design) that randomised 1621 participants.This study compared the daily application of sunscreen compared with discretionary use of sunscreen, with or without beta-carotene administration, in the general population. The study was undertaken in Australia; 55.2% of participants had fair skin, and they were monitored for 4.5 years for new cases of BCC or cSCC assessed by histopathology. We found this study to be at low risk of bias for domains such as allocation, blinding, and incomplete outcome data. However, we found multiple unclear risks related to other biases, including an unclear assessment of possible interactions between the effects of the different interventions evaluated (that is, sunscreen and beta-carotene). We found no difference in terms of the number of participants developing BCC (n = 1621; risk ratio (RR) 1.03, 95% confidence interval (CI) 0.74 to 1.43) or cSCC (n = 1621; RR 0.88, 95% CI 0.50 to 1.54) when comparing daily application of sunscreen with discretionary use, even when analyses were restricted to groups without beta-carotene supplementation. This evidence was of low quality, which means that there is some certainty that future studies may alter our confidence in this evidence.We reported adverse events in a narrative way and included skin irritation or contact allergy.We identified no studies that evaluated other sun protection measures, such as the use of sun-protective clothing, sunglasses, or hats, or seeking the shade when outdoors.

AUTHORS' CONCLUSIONS

In this review, we assessed the effect of solar protection in preventing the occurrence of new cases of keratinocyte cancer. We only found one study that was suitable for inclusion. This was a study of sunscreens, so we were unable to assess any other forms of sun protection. The study addressed our prespecified primary outcomes, but not most of our secondary outcomes. We were unable to demonstrate from the available evidence whether sunscreen was effective for the prevention of basal cell carcinoma (BCC) or cutaneous squamous cell carcinoma (cSCC).Our certainty in the evidence was low because there was a lack of histopathological confirmation of BCC or cSCC in a significant percentage of cases. Amongst other sources of bias, it was not clear whether the study authors had assessed any interaction effects between the sunscreen and beta-carotene interventions. We think that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

Occupational sunscreen use among US Hispanic outdoor workers

Background

Occupational ultraviolet radiation (UVR) exposure is a risk factor for skin cancer, and Hispanic individuals are over-represented in a number of outdoor occupations (e.g., farming, landscaping). This study examined predictors of occupational sunscreen use in a group of US Hispanic adults who work outdoors.

Results

A population-based sample of outdoor workers (n = 149, 85 % male) completed survey measures regarding their demographics, melanoma risk, perceived skin cancer risk, skin cancer knowledge, and their occupational sunscreen use. Sixty-nine percent of the sample reported never or rarely wearing sunscreen while working outdoors. Being female (p = .02), having a higher level of education (p = .03), and residing at a higher latitude (p = .04) were associated with more frequent sunscreen use.

Conclusions

This study highlights the importance of interventions to promote sun protection behaviors among US Hispanic outdoor workers, and identifies potential intervention targets.

Sunburn, Thermal, and Chemical Injuries to the Skin

Sunburn, thermal, and chemical injuries to the skin are common in the United States and worldwide. Initial management is determined by type and extent of injury with special care to early management of airway, breathing, and circulation. Fluid management has typically been guided by the Parkland formula, whereas some experts now question this. Each type of skin injury has its own pathophysiology and resultant complications. All primary care physicians should have at least a basic knowledge of management of acute and chronic skin injuries.

Transtheoretical Model Constructs' Longitudinal Prediction of Sun Protection Over 24 Months

PURPOSE

This research examined dynamic transtheoretical model (TTM) constructs for adopting sun protection practices. This secondary data analysis pooled four large population-based TTM-tailored intervention studies and examined use of constructs across three groups, organized by longitudinal progress: maintainers, relapsers, and stable non-changers.

METHODS

A total of 3463 adults, in the USA, who met criteria for unsafe sun exposure at baseline received a TTM-tailored computerized intervention at baseline, 6 months, and 12 months. The final analytic sample consisted of 1894 participants; the majority were female, White, married, and middle-aged. The three groups were assessed with reliable and valid scales assessing use of TTM constructs at baseline, 6 months, 12 months, and 24 months. Analyses included a MANOVA followed by a series of ANOVAs, with Tukey follow-up tests assessing differences in use of TTM constructs across the three groups at each timepoint.

RESULTS

Findings demonstrated that relapsers and maintainers were similar in their use of most TTM processes of change at baseline, with the exception of Consciousness Raising, Stimulus Control, Reinforcement Management, and Self-Liberation.

CONCLUSIONS

These findings suggest that although relapsers reverted to unsafe sun practices, their overall greater use of processes of change indicates that their change efforts remain better than that of stable non-changers.

Assessing the current market of sunscreen: a cross-sectional study of sunscreen availability in three metropolitan counties in the United States

Sunscreen use is recommended for the prevention of sunburn and skin cancer. Little is known regarding sunscreen availability in high versus low income communities. We analyzed sunscreen availability in three large metropolitan counties to determine the relationship between availability and community demographics. We included sun care products in all pharmacies and supermarkets open as of July 2013 in representative high and low income zip codes in Cook County, Illinois, Miami-Dade County, Florida, and San Diego County, California. We recorded the percentage of tanning oil, sunscreens with a sun protection factor (SPF) < 15, SPF > 15, physical sunscreens, spray sunscreens, mean price per ounce (PPO), and mean SPF. Of the total products assessed, 11.0% were tanning oils, with physical sunscreens accounting for only 3.4% of the available sunscreens and 46.2% of sunscreens being spray-on. A comparison between higher and lower income zip codes demonstrated a significantly increased percentage of sunscreens with SPF < 15 in high income zip codes. Lower income zip codes had higher percentages of sunscreens with SPF > 15 and higher PPO, even when taking into account SPF. Further studies of sunscreen usage patterns in different populations must take into account sunscreen availability and price, as these significantly differ based on the community demographic.

Transient receptor potential vanilloid 4 (TRPV4) is downregulated in keratinocytes in human non-melanoma skin cancer

A subgroup of the transient receptor potential (TRP) channels, including vanilloid 1 (TRPV1), TRPV2, TRPV3, TRPV4, and TRP ankyrin 1 (TRPA1), is expressed in cutaneous peptidergic somatosensory neurons, and has been found in skin non-neuronal cells, such as keratinocytes. Different cancer cells express TRPs, where they may exert either pro- or antitumorigenic roles. Expression and function of TRPs in skin cancers have been, however, poorly investigated. Here, we have studied the distribution and expression of TRPs by immunohistochemistry and messenger RNA (mRNA) in human healthy skin and human keratinocytic tumors, including intraepidermal proliferative disorders (solar keratosis (SK) and Bowen's disease), and non-melanoma skin cancer (NMSC; basal cell and squamous cell carcinomas). Similar TRPV1, TRPV2, and TRPV3 staining was found in keratinocytes from healthy and tumor tissues. TRPA1 staining was increased solely in SK samples. However, the marked TRPV4 staining and TRPV4 mRNA expression, observed in healthy or inflamed skin, was abrogated both in premalignant lesions and NMSC. In a human keratinocyte cell line (HaCaT), TRPV4 stimulation released IL-8, which in turn downregulated TRPV4 expression. Selective reduction in TRPV4 expression could represent an early biomarker of skin carcinogenesis. Whether the cytokine-dependent, autocrine pathway that results in TRPV4 downregulation contributes to NMSC mechanism remains to be determined.

UVB-irradiated keratinocytes induce melanoma-associated ganglioside GD3 synthase gene in melanocytes via secretion of tumor necrosis factor α and interleukin 6

Although expression of gangliosides and their synthetic enzyme genes in malignant melanomas has been well studied, that in normal melanocytes has been scarcely analyzed. In particular, changes in expression levels of glycosyltransferase genes responsible for ganglioside synthesis during evolution of melanomas from melanocytes are very important to understand roles of gangliosides in melanomas. Here, expression of glycosyltransferase genes related to the ganglioside synthesis was analyzed using RNAs from cultured melanocytes and melanoma cell lines. Quantitative RT-PCR revealed that melanomas expressed high levels of mRNA of GD3 synthase and GM2/GD2 synthase genes and low levels of GM1/GD1b synthase genes compared with melanocytes. As a representative exogenous stimulation, effects of ultraviolet B (UVB) on the expression levels of 3 major ganglioside synthase genes in melanocytes were analyzed. Although direct UVB irradiation of melanocytes caused no marked changes, culture supernatants of UVB-irradiated keratinocytes (HaCaT cells) induced definite up-regulation of GD3 synthase and GM2/GD2 synthase genes. Detailed examination of the supernatants revealed that inflammatory cytokines such as TNFα and IL-6 enhanced GD3 synthase gene expression. These results suggest that inflammatory cytokines secreted from UVB-irradiated keratinocytes induced melanoma-associated ganglioside synthase genes, proposing roles of skin microenvironment in the promotion of melanoma-like ganglioside profiles in melanocytes.

Skin cancer: role of ultraviolet radiation in carcinogenesis

UV radiation is a carcinogen known to play a role in the development of non-melanoma and melanoma skin cancers. Acute and chronic exposure to UV radiation causes clinical and biological effects that promote the unregulated proliferation of skin cells. In recent decades, changes in climate and increased air pollution have led to environmental changes that increase UV light transmission. In this chapter, we discuss sources of UV radiation that are relevant to human health, as well as the acute and chronic effects that result from UV radiation exposure.