Tanning and skin cancer

Photoaging: Current Concepts on Molecular Mechanisms, Prevention, and Treatment

Photoaging is the consequence of chronic exposure to solar irradiation, encompassing ultraviolet (UV), visible, and infrared wavelengths. Over time, this exposure causes cumulative damage, leading to both aesthetic changes and structural degradation of the skin. These effects manifest as rhytids, dyschromia, textural changes, elastosis, volume loss, telangiectasias, and hyperkeratosis, collectively contributing to a prematurely aged appearance that exceeds the skin's chronological age. The hallmarks of photoaging vary significantly by skin phototype. Skin of color tends to exhibit dyschromia and features associated with "intrinsic" aging, such as volume loss, while white skin is more prone to "extrinsic" aging characteristics, including rhytids and elastosis. Moreover, susceptibility to different wavelengths within the electromagnetic spectrum also differs by skin phototype, influencing the clinical presentation of photoaging, as well as prevention and treatment strategies. Fortunately, photoaging-and its associated adverse effects-is largely preventable and, to some extent, reversible. However, effective prevention and treatment strategies require careful tailoring to an individual's skin type. In this review, we summarize molecular mechanisms underlying photoaging, examine its clinical manifestations, outline risk factors and prevention strategies, and highlight recent advancements in its treatment.

Current insights and future perspectives of ultraviolet radiation (UV) exposure: Friends and foes to the skin and beyond the skin

Ultraviolet (UV) radiation is ubiquitous in the environment, which has been classified as an established human carcinogen. As the largest and outermost organ of the body, direct exposure of skin to sunlight or UV radiation can result in sunburn, inflammation, photo-immunosuppression, photoaging and even skin cancers. To date, there are tactics to protect the skin by preventing UV radiation and reducing the amount of UV radiation to the skin. Nevertheless, deciphering the essential regulatory mechanisms may pave the way for therapeutic interventions against UV-induced skin disorders. Additionally, UV light is considered beneficial for specific skin-related conditions in medical UV therapy. Recent evidence indicates that the biological effects of UV exposure extend beyond the skin and include the treatment of inflammatory diseases, solid tumors and certain abnormal behaviors. This review mainly focuses on the effects of UV on the skin. Moreover, novel findings of the biological effects of UV in other organs and systems are also summarized. Nevertheless, the mechanisms through which UV affects the human organism remain to be fully elucidated to achieve a more comprehensive understanding of its biological effects.

Next-generation sequencing reveals the biological significance of the N(2),3-ethenoguanine lesion in vivo

Etheno DNA adducts are a prevalent type of DNA damage caused by vinyl chloride (VC) exposure and oxidative stress. Etheno adducts are mutagenic and may contribute to the initiation of several pathologies; thus, elucidating the pathways by which they induce cellular transformation is critical. Although N(2),3-ethenoguanine (N(2),3-εG) is the most abundant etheno adduct, its biological consequences have not been well characterized in cells due to its labile glycosidic bond. Here, a stabilized 2'-fluoro-2'-deoxyribose analog of N(2),3-εG was used to quantify directly its genotoxicity and mutagenicity. A multiplex method involving next-generation sequencing enabled a large-scale in vivo analysis, in which both N(2),3-εG and its isomer 1,N(2)-ethenoguanine (1,N(2)-εG) were evaluated in various repair and replication backgrounds. We found that N(2),3-εG potently induces G to A transitions, the same mutation previously observed in VC-associated tumors. By contrast, 1,N(2)-εG induces various substitutions and frameshifts. We also found that N(2),3-εG is the only etheno lesion that cannot be repaired by AlkB, which partially explains its persistence. Both εG lesions are strong replication blocks and DinB, a translesion polymerase, facilitates the mutagenic bypass of both lesions. Collectively, our results indicate that N(2),3-εG is a biologically important lesion and may have a functional role in VC-induced or inflammation-driven carcinogenesis.

U.S. Food and Drug Administration approval: vismodegib for recurrent, locally advanced, or metastatic basal cell carcinoma

The data and regulatory considerations leading to the U.S. Food and Drug Administration (FDA) January 30, 2012 approval of Erivedge (vismodegib) capsules for the treatment of patients with recurrent, locally advanced, or metastatic basal cell carcinoma (BCC) are described. The FDA's approval decision was based primarily on the results observed in a single-arm, parallel cohort, international trial of vismodegib, administered orally at 150 mg daily until disease progression, in patients with pathologically confirmed, recurrent, locally advanced basal cell carcinoma (laBCC) or metastatic basal cell carcinoma (mBCC). An independent review committee confirmed an overall response rate (ORR) of 30.3% [95% confidence interval (CI): 15.6-48.2] in 33 patients with mBCC and an ORR of 42.9% (95% CI: 30.5-56.0) in 63 patients with laBCC; median response durations were 7.6 months and 7.6 months for patients with mBCC and laBCC, respectively. The most common adverse reactions were muscle spasms, alopecia, dysgeusia, weight loss, fatigue, nausea, diarrhea, decreased appetite, constipation, cough, arthralgias, vomiting, headache, ageusia, insomnia, and upper respiratory tract infection. Animal toxicology studies confirmed that vismodegib is a potent teratogenic agent. Approval was based on durable objective tumor responses supported by knowledge of the pathologic role of Hedgehog signaling in BCC and acceptable toxicity in a population without effective alternative therapies.

Epigenetic changes in Basal Cell Carcinoma affect SHH and WNT signaling components

Background

The genetic background of Basal Cell Carcinoma (BCC) has been studied extensively, while its epigenetic makeup has received comparatively little attention. Epigenetic alterations such as promoter hypermethylation silence tumor suppressor genes (TSG) in several malignancies.

Objective

We sought to analyze the promoter methylation status of ten putative (tumor suppressor) genes that are associated with Sonic Hedgehog (SHH), WNT signaling and (hair follicle) tumors in a large series of 112 BCC and 124 healthy control samples by methylation-specific PCR.

Results

Gene promoters of SHH (P = 0.016), adenomatous polyposis coli (APC) (P = 0.003), secreted frizzled-related protein 5 (SFRP5) (P = 0.004) and Ras association domain family 1A (RASSF1A) (P = 0.023) showed significantly more methylation in BCC versus normal skin. mRNA levels of these four genes were reduced for APC and SFRP5 in BCC (n = 6) vs normal skin (n = 6). Down regulation of SHH, APC and RASSF1A could be confirmed on protein level as well (P<0.001 for all genes) by immunohistochemical staining. Increased canonical WNT activity was visualized by β-catenin staining, showing nuclear β-catenin in only 28/101 (27.7%) of BCC. Absence of nuclear β-catenin in some samples may be due to high levels of membranous E-cadherin (in 94.1% of the samples).

Conclusions

We provide evidence that promoter hypermethylation of key players within the SHH and WNT pathways is frequent in BCC, consistent with their known constitutive activation in BCC. Epigenetic gene silencing putatively contributes to BCC tumorigenesis, indicating new venues for treatment.

Epidemiology of basal cell carcinoma

Basal cell carcinoma is the most common malignant neoplasm in humans and its incidence has increased over the last decades. Its high frequency significantly burdens the health system, making the disease a public health issue. Despite the low mortality rates and the rare occurrence of metastases, the tumor may be locally invasive and relapse after treatment, causing significant morbidity. Exposure to ultraviolet radiation is the main environmental risk factor associated with its cause. However, other elements of risk are described, such as light skin phototypes, advanced age, family history of skin carcinoma, light eyes and blond hair, freckles in childhood and immunosuppression. Behavioral aspects such as occupational sun exposure, rural labor and sunburns at a young age also play a role. Between 30% and 75% of the sporadic cases are associated with patched hedgehog gene mutation, but other genetic changes are also described. The tumor is commonly found in concomitance with skin lesions related to chronic sun exposure, such as actinic keratoses, solar lentigines and facial telangiectasia. The prevention of basal cell carcinoma is based on the knowledge of risk factors, early diagnosis and treatment, as well as on the adoption of specific measures, particularly in susceptible populations. The authors present a review of the epidemiology of basal cell carcinoma.

Demographic and Tumor Characteristics of Patients Diagnosed with Nonmelanoma Skin Cancer: 13-Year Retrospective Study

Background:

The incidence of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) is increasing worldwide; however, this varies by region. To date, there are limited data about trends of nonmelanoma skin cancer (NMSC) in Canada.

Objective:

To determine the demographic and tumor characteristic changes in patients diagnosed with BCC and SCC from 1993 to 2005 in a dermatology practice in Vancouver, British Columbia.

Method:

A retrospective chart review was conducted on patients with biopsy-confirmed NMSC between 1993 and 2005. Demographic and tumor characteristics were documented for the first two incident BCCs and SCCs per patient, and a descriptive data analysis was undertaken.

Results:

A total of 1,177 NMSCs were identified from 885 patient charts. The number of BCCs increased from 1993 to 2003 and then decreased until 2005. BCCs and SCCs were generally diagnosed in older people (60+ years); however, an important group of younger patients (20–39 years) was also diagnosed with BCCs. BCCs and SCCs were most commonly seen on the head and neck, but the leg was a common location for SCC in women.

Conclusion:

NMSC is prevalent in British Columbia. These results highlight the fact that NMSC can affect individuals younger than 40 years old. Prevention strategies are warranted to reduce the burden of NMSC in British Columbia.

Geography, facilities, and promotional strategies used to encourage indoor tanning in New York City

There is emerging evidence for the relationship between indoor tanning and melanoma. Eighty-five indoor tanning facilities in New York City were observed to determine number of tanning machines, pricing, promotions, products, and hours. Census data by zip code was used to determine population density, gender, race, age, percent living in poverty, percent unemployed, and percent college educated of areas in which tanning facilities were located. Pricing varied by the type of machine, number of sessions purchased, and single versus bundled sessions. Facilities were located in areas that had greater population density and slightly greater median age. Compared with the zip code areas with no facilities, those with tanning facilities had a higher proportion of white residents; a lower proportion of residents living in poverty and unemployed; and a higher proportion of residents with a college education. Our data suggest that the strategic location of facilities and promotions used in NYC seek to maximize patronage by those with comparatively high levels of income and education and who may be more influenced by the social desirability of artificial tanning. Long-term interventions aimed at changing social norms regarding tan skin are needed.

The potential carcinogenic risk of tanning beds: clinical guidelines and patient safety advice

INTRODUCTION

In 2009, the WHO listed ultraviolet (UV) radiation as a group 1 carcinogen. In spite of this, each year, millions of people tan indoor in Western countries. The aim of this review is to summarize evidence of tanning bed carcinogenesis and to present guidelines for use of tanning beds and patient safety advice.

METHODS

A narrative review of the literature was conducted based on both PubMed and Medline searches and on literature review of the retrieved papers.

RESULTS

Use of indoor tanning beds represents a significant and avoidable risk factor for the development of both melanoma and nonmelanoma skin cancers. Frequent tanners are more often adolescent females. Tanning beds have additional potential adverse effects such as burns, solar skin damage, infection, and possibly also addictive behavior.

DISCUSSION

The effort in preventing UV light-induced carcinogenesis should currently be aimed at developing new strategies for public health information. Tanning beds are one preventable source of UV radiation. In the majority of people solar UV radiation continues to be the major factor and therefore anti-tanning campaigns must always include sunbathers.

Basal cell carcinoma: what's new under the sun

Basal cell carcinoma (BCC) is the most common skin cancer in white populations with an increasing incidence worldwide, thereby imposing an important public health problem. Its etiology is still unclear, but existing data indicate that the risk for BCC development is of multifactorial origin and results from the interplay of both constitutional and environmental factors. Yet, UV radiation (UVR) is believed to be the predominant causative risk factor in the pathogenesis of BCC. For years, BCC and squamous cell carcinoma (SCC) have been grouped together as "nonmelanoma skin cancer." However, it seems that there are considerable biologic differences between BCC and SCC, and thus each type of epithelial cancer should be addressed separately. The present review provides an overview of the intriguing etiologic link of BCC with UVR and attempts a comprehensive review of recent epidemiologic and molecular evidence that supports this association.

Classifying ambiguous melanocytic lesions with FISH and correlation with clinical long-term follow up

Recently, initial studies describing the use of multicolor fluorescence in situ hybridization (FISH) for classifying melanocytic skin lesions have been published demonstrating a high sensitivity and specificity in discriminating melanomas from nevi. However, the majority of these studies included neither histologically ambiguous lesions nor a clinical long-term follow up. This study was undertaken to validate a special multicolor FISH test in histologically ambiguous melanocytic skin lesions with known clinical long-term follow up. FISH was scored by three independent pathologists in a series of 22 melanocytic skin lesions, including 12 ambiguous cases using four probes targeting chromosome 6p25, centromere 6, 6q23, and 11q13. The FISH results were compared with array comparative genomic hybridization data and correlated to the clinical long-term follow up (mean: 65 months). Pair-wise comparison between the interpretations of the observers showed a moderate to substantial agreement (kappa 0.47-0.61). Comparing the FISH results with the clinical behavior reached an overall sensitivity of 60% and a specificity of 50% (chi(2)=0.25; P=0.61) for later development of metastases. Comparison of array comparative genomic hybridization data with FISH analyses did not yield significant results but array comparative genomic hybridization data demonstrated that melanocytic skin lesions with the development of metastases showed significantly more chromosomal aberrations (P<0.01) compared with melanocytic skin lesions without the development of metastases. The FISH technique with its present composition of locus-specific probes for RREB1/MYB and CCND1 did not achieve a clinically useful sensitivity and specificity. However, a reassessment of the probes and better standardization of the method may lead to a valuable diagnostic tool.

[Update on photoprotection in children]

Children are one of the population groups in which the photo-protection must be maximised. Firstly, because they take part in outdoor activities more often than adults. Secondly, because the principal risk factor for all types of skin cancer is ultraviolet radiation, and in particular, cumulative exposure during childhood. Hence, decreasing exposure to ultraviolet radiation in childhood has the potential to significantly lower the incidence of most forms of skin cancer. Photoprotection includes behavioural measures to protect the skin from sun exposure, e.g. sun protective clothes, hats, sunglasses, and sunscreens. It is necessary to provide information on aphotoprotection to parents, and, above all, to children, using educational campaigns to increase knowledge of photoprotection to help change attitudes towards sun exposure. Dermatologists and Paediatricians play a essential role in this educational work. In this article we review the latest information regarding paediatric sun protection, the new sunscreens, and the recent sun protection educational programs.

Vitamin D: bone and beyond, rationale and recommendations for supplementation

Adequate vitamin D status is necessary and beneficial for health, although deficiency plagues much of the world's population. In addition to reducing the risk for bone disease, vitamin D plays a role in reduction of falls, as well as decreases in pain, autoimmune diseases, cancer, heart disease, mortality, and cognitive function. On the basis of this emerging understanding, improving patients' vitamin D status has become an essential aspect of primary care. Although some have suggested increased sun exposure to increase serum vitamin D levels, this has the potential to induce photoaging and skin cancer, especially in patients at risk for these conditions. Vitamin D deficiency and insufficiency can be both corrected and prevented safely through supplementation.

Tanning behavior of London-area youth

BACKGROUND

The World Health Organization recommends that tanning parlors not be used by individuals under age 18 years. The impact of self-tanners on tanning parlor and sunscreen use by Canadian teens is unknown.

OBJECTIVE

To determine teens' use of, knowledge of, attitudes toward, and behavior regarding tanning parlors, self-tanning products, and sunscreen.

METHODS

Self-report questionnaire of grade 10 students in Thames Valley district, Ontario.

RESULTS

Indoor tanning parlors were used by 14%, self-tanners by 28%, and sunscreen daily or most days by 36%. Use was more common in females. There was a strong association between parental and child use of tanning parlors and use of self-tanners. Sixty-two percent believe that self-tanners give adequate photoprotection.

CONCLUSIONS

Further education is required to address teen tanning parlor use, infrequent sunscreen use, and lack of knowledge about the safety of tanning parlors and self-tanning products.

Indoor tanning use among adolescents in the US, 1998 to 2004

BACKGROUND

A recent meta-analysis found that indoor tanning use before the age of 35 years increases the risk of melanoma, supporting policies to restrict indoor tanning use among adolescents. The objectives of the current study were to provide a national assessment of prevalence and trends of indoor tanning use among US adolescents, to examine changes in the prevalence of indoor tanning use from 1998 to 2004 in relation to state policies on minors' access, and to assess the prevalence of burns, rashes, and infections among users.

METHODS

Two cross-sectional population-based surveys of US youths ages 11 to 18 years and their parents/guardians conducted in 1998 (N=1196) and 2004 (N=1613) used identical questions to assess use of indoor tanning and correlates of this behavior.

RESULTS

The prevalence of indoor tanning use by adolescents within the past year changed little from 1998 to 2004 (10% to 11%). In states with policies regarding minors' access to indoor tanning, the prevalence stayed the same or decreased from 1998 to 2004, whereas it increased in states without such policies. Neither trend was found to be statistically significant. Youth tanning attitudes, parental indoor tanning use, and parents' permission were strongly associated with youth use of indoor tanning. Fifty-eight percent of users reported burns from indoor tanning.

CONCLUSIONS

The presence of state legislation restricting minors' access to indoor tanning appears to have limited effectiveness, perhaps because most states' policies permit use with parental consent. Multipronged approaches are needed to reduce indoor tanning use in youths.

Prognostic criteria for squamous cell cancer of the skin

BACKGROUND

Non-well-differentiated cutaneous squamous cell carcinomas may display a more aggressive behavior. It is important to better define prognostic criteria for these tumors.

METHODS

This was a retrospective case-control analysis of a squamous cell carcinoma database. Patients with non-well-differentiated and well-differentiated tumors were matched based on site of tumor, age, and immunocompromised status. Comparisons included demographics, histology, immunohistochemical protein expressions (Ki-67, p53, E-cadherin, cyclin D1), and clinical outcomes.

RESULTS

Demographic features were similar between cases (n=30) and controls (n=30). Non-well-differentiated tumors were larger (1.8 cm versus 1.3 cm, P=0.08), deeper (0.81 cm versus 0.32 cm, P<0.0001), and had greater recurrence (P=0.003). Non-well-differentiated tumors showed increased proliferation rate, Ki-67 index (77% versus 61%, P=0.001); no significant difference in activity of p53, E-cadherin, and cyclin D1 between the two groups.

CONCLUSIONS

Tumor differentiation and depth are important pathologic and prognostic criteria for cutaneous squamous cell carcinoma. Immunohistochemistry helps describe patterns of biomarker protein expression and may exemplify aggressive subtypes.

UV and pigmentation: molecular mechanisms and social controversies

Ultraviolet radiation (UVR) is an essential risk factor for the development of premalignant skin lesions as well as of melanoma and non-melanoma skin cancer. UVR exerts many effects on the skin, including tanning, carcinogenesis, immunomodulation, and production of vitamin D. Vitamin D (vit D) is important in the maintenance of healthy bones as well as other purported beneficial effects, amongst which is the potential for reducing risk of malignancy--though oral supplementation is fully capable of maintaining systemic levels. The known medical harm from UV exposure relates primarily to cancer of the skin--the most common organ in man to be affected by cancer. In this review, we summarize the knowledge about the ultraviolet (UV) response in regards to inflammation, immunosuppression, carcinogenesis and the tanning response. We also discuss vit D and UV, as well as public health implications of tanning behavior and commercial interests related to the promotion of UV exposure. As the most ubiquitous human carcinogen, UVR exposure represents both a challenge and enormous opportunity in the realm of skin cancer prevention.

Sirolimus reduces the incidence and progression of UVB-induced skin cancer in SKH mice even with co-administration of cyclosporine A

Transplant immunosuppressants have been implicated in the increased incidence of non-melanoma skin cancer in transplant recipients, most of whom harbor considerable UVB-induced DNA damage in their skin prior to transplantation. This study was designed to evaluate the effects of two commonly used immunosuppressive drugs, cyclosporine A (CsA) and sirolimus (SRL), on the development and progression of UVB-induced non-melanoma skin cancer. SKH-1 hairless mice were exposed to UVB alone for 15 weeks, and then were treated with CsA, SRL, or CsA+SRL for 9 weeks following cessation of UVB treatment. Compared with vehicle, CsA treatment resulted in enhanced tumor size and progression. In contrast, mice treated with SRL or CsA+SRL had decreased tumor multiplicity, size, and progression compared with vehicle-treated mice. CsA, but not SRL or combined treatment, increased dermal mast cell numbers and TGF-beta1 levels in the skin. These findings demonstrate that specific immunosuppressive agents differentially alter the cutaneous tumor microenvironment, which in turn may contribute to enhanced development of UVB-induced skin cancer in transplant recipients. Furthermore, these results suggest that CsA alone causes enhanced growth and progression of skin cancer, whereas co-administration of SRL with CsA causes the opposite effect. JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article please go to http://network.nature.com/group/jidclub

Targeting mutant p53 shows promise for sunscreens and skin cancer

Chronic exposure to UV light is a risk factor for skin cancer in which signature mutations in the p53 tumor suppressor gene occur due to DNA damage and contribute to cancer development. In this issue of the JCI, Tang et al. report on their study of a nonimmunodeficient mouse model of UVB-induced skin cancer and human skin carcinoma cells and show that the mutant p53 conformation-modifying drug CP-31398 not only treats these tumors but also prevents them (see the related article beginning on page 3753). These studies have important implications for chemoprevention as well as therapy of common, mutant p53-driven tumors.

Epidemiology of nonmelanoma skin cancer (NMSC) in Europe: accurate and comparable data are needed for effective public health monitoring and interventions

Nonmelanoma skin cancer (NMSC) is the most common malignancy occurring in white populations. It is currently becoming an important challenge in terms of public health management as the increasing incidence rates will probably have a tremendous impact on healthcare costs. Possible factors driving this rise in NMSC numbers are increases in both acute and prolonged UV exposure together with increasing numbers of older people in the population. A better understanding of NMSC epidemiology in Europe is essential if an evidence-based European-wide public health policy is to be developed. It is obvious this can only be achieved by recording and analysing comparative epidemiological data. Finally, by improving the skin examination training for physicians, developing guidelines and exchanging best practices, a high level of healthcare could be provided for NMSC.

UV light abuse and high-risk tanning behavior among undergraduate college students

BACKGROUND

The failure of skin cancer prevention efforts to alter tanning behaviors may be a result of the addictive nature of UV light.

OBJECTIVE

This study attempts to determine the prevalence of UV light substance-related disorder (SRD).

METHODS

A survey was administered to undergraduate college students. The cut down, annoyed, guilty, eye-opener questionnaire was used to determine existence of SRD.

RESULTS

Of 385 respondents, 12% scored positively on the cut down, annoyed, guilty, eye-opener indicating SRD. Women, indoor tanners, students with tanning family and friends, and frequent tanners were significantly more likely than their peers to score positively.

LIMITATIONS

The small size is a limitation of this study as results may not be generalizable to larger populations. There also may be self-report bias.

CONCLUSIONS

A significant proportion of college students demonstrate evidence of SRD with respect to UV light.

A polypeptide from Chlamys farreri abolishes UV-induced apoptosis in murine thymocytes in vitro

Previously we reported that a polypeptide from Chlamys farreri (PCF) was a potent photoprotective agent against ultraviolet (UV) irradiation in vitro. To understand the mechanism by which PCF protects cells from irradiation, we studied anti-apoptotic effects of PCF against UV irradiation on the murine thymocytes in vitro. MTT and flow cytometric analysis assays showed that 2h pretreatment with PCF completely abolished UV induced cell death. TEM examination showed that PCF fully protected the ultrastructure of thymocytes exposed to UV irradiation. Lipid peroxidation and intracellular reactive oxygen species assays indicated that PCF efficiently blocked production of reactive oxygen intermediates induced by UV irradiation. Further, PCF protected UV-irradiated thymocytes from losing mitochondrial transmembrane potential and DNA fragmentation. Based on these observations we propose that PCF is a potent anti-apoptotic factor, which protects cells from irradiation at multiple steps.