UVA-induced melanocytic lesions

Association of sunbed use with skin cancer risk factors in Europe: an investigation within the Euromelanoma skin cancer prevention campaign

INTRODUCTION

Sunbed use has been significantly associated with increased risk of melanoma and non-melanoma skin cancer (NMSC), but its relationship with melanoma's risk factors such as high nevus count, atypical nevi and lentigines is poorly studied. Euromelanoma is a skin cancer prevention campaign conducted all over Europe. It offers a once-a-year screening during which participants' data, including sunbed use and phenotype, are collected via questionnaires.

OBJECTIVES

To investigate the association of sunbed use with nevus count, atypical nevi, lentigines and suspicion of skin cancer.

METHODS

To ensure reliability of the data, we defined inclusion and exclusion criteria for countries' eligibility for the risk analysis. Multivariate logistic regression models (including age, gender, education, skin type, family history of melanoma, personal history of skin cancer, any sun exposure and any sunscreen use) were used to calculate summary odds ratios (SORs) of each clinical endpoint for ever sunbed use.

RESULTS

Overall, 227 888 individuals from 30 countries completed the Euromelanoma questionnaire. After the data quality check, 16 countries were eligible for the multivariate analysis, for a total of 145 980 participants (64.8% females; median age 43 years; 62.3% highly educated; 28.5% skin type I-II; 11.0% ever sunbed use). Ever sunbed use was independently associated with nevus count >50 [SOR = 1.05 (1.01-1.10)], atypical nevi [SOR = 1.04 (1.00-1.09)], lentigines [SOR = 1.16 (1.04-1.29)] and suspicion of melanoma [SOR = 1.13 (1.00-1.27)]. Conversely, no significant association was found between ever sunbed use and suspicion of NMSC [SOR = 1.00 (0.91-1.10)].

CONCLUSIONS

Indoor tanning is significantly associated with well-recognized risk factors for melanoma (including high nevus count, presence of atypical nevi and lentigines) as well as suspicion of melanoma within the Euromelanoma screenees. In order to reduce the prevalence of melanoma risk factors, avoidance/discontinuation of sunbed use should always be encouraged, especially but not exclusively for individuals with high-risk phenotypes.

Ultraviolet and laser radiation safety

Both ultraviolet radiation and laser radiation occupy pmt of the Spectrum designated "optical radiation". Thus, measurement techniques are similar and the same organs (eyes and skin) are at risk from accidental exposure. However, the equipment used to produce ultraviolet and laser radiation differs substantially and the harm caused by each type of radiation is also different. Another significant difference arises from the fact that ultraviolet radiation is natural with associated general population exposure. Consequently, the present article reviews the current status of both ultraviolet and laser radiation with the material divided into two sections where each hazard is considered separately.

Ultraviolet A and melanoma: a review

The incidence and mortality rates of melanoma have risen for many decades in the United States. Increased exposure to ultraviolet (UV) radiation is generally considered to be responsible. Sunburns, a measure of excess sun exposure, have been identified as a risk factor for the development of melanoma. Because sunburns are primarily due to UVB (280-320 nm) radiation, UVB has been implicated as a potential contributing factor to the pathogenesis of melanoma. The adverse role of UVA (320-400 nm) in this regard is less well studied, and currently there is a great deal of controversy regarding the relationship between UVA exposure and the development of melanoma. This article reviews evidence in the English-language literature that surrounds the controversy concerning a possible role for UVA in the origin of melanoma. Our search found that UVA causes DNA damage via photosensitized reactions that result in the production of oxygen radical species. UVA can induce mutations in various cultured cell lines. Furthermore, in two animal models, the hybrid Xiphophorus fish and the opossum (Mondelphis domestica), melanomas and melanoma precursors can be induced with UVA. UVA radiation has been reported to produce immunosuppression in laboratory animals and in humans. Some epidemiologic studies have reported an increase in melanomas in users of sunbeds and sunscreens and in patients exposed to psoralen and UVA (PUVA) therapy. There is basic scientific evidence of the harmful effects of UVA on DNA, cells and animals. Collectively, these data suggest a potential role for UVA in the pathogenesis of melanoma. To date evidence from epidemiologic studies and clinical observations are inconclusive but seem to be consistent with this hypothesis. Additional research on the possible role of UVA in the pathogenesis of melanoma is required.

Tanning salon exposure and molecular alterations

BACKGROUND

Human studies of the short-term cellular effects of tanning salon exposures are lacking. Findings of such studies may prove extremely helpful in educating consumers considering or currently attending tanning salons.

OBJECTIVE

Our purpose was to determine whether tanning salon exposure causes DNA alterations and p53 protein expression in epidermal keratinocytes and/or circulating peripheral lymphocytes.

METHODS

Eleven subjects received 10 full-body tanning salon exposures over a 2-week period. UV-induced DNA cyclobutane pyrimidine dimers and p53 protein expression were examined, comparing pretreatment peripheral blood lymphocytes and epidermal biopsy specimens with analogous specimens obtained after the 10 tanning salon exposures.

RESULTS

Cyclobutane pyrimidine dimers in DNA and p53 protein expression were detected in epidermal keratinocytes, but were absent in lymphocytes.

CONCLUSION

Similar to outdoor sun exposure, short-term recreational tanning salon exposure causes molecular alterations believed essential in the development of skin cancer.

The effect of suntan parlor exposure on delayed and contact hypersensitivity

Cutaneous and systemic immune function are believed to play an important role in cutaneous carcinogenesis. We therefore sought to determine whether the suntan parlor radiation sources commonly used in the United States cause measurable qualitative suppression of immune function and quantitative alterations in circulating T cell subpopulations. Subjects (n = 22) were recruited and randomly assigned to receive suntan parlor exposures (10 full-body UV exposures over a 2 week period, shielding only the right flexural arm) or no exposure. Baseline circulating T lymphocyte subpopulations (T helper lymphocyte, CD4; T suppressor/cytotoxic lymphocyte, CD8) were measured. Two weeks later (upon completion of UV exposures for those in this group), circulating T cell subpopulations were measured and dinitrochlorobenzene (DNCB) sensitization (in the UV group, on the UV-exposed buttock) was performed. Subsequent DNCB elicitation was performed in a bilateral fashion (in the UV group, on the right UV-shielded and the left UV-exposed upper arm). We found that subjects in the UV group demonstrated localized suppression of contact hypersensitivity sensitization and elicitation and also an increase in circulating CD8 cells when compared to the control group (P < or = 0.05). We conclude that suntan parlor exposures, as typically received in this country, suppress contact hypersensitivity and increase the circulating T suppressor/cytotoxic cell number quantity.

Risk of cutaneous malignant melanoma in relation to use of sunbeds: further evidence for UV-A carcinogenicity

In a population-based, matched, case-control study from southern Sweden of 571 patients with a first diagnosis of cutaneous malignant melanoma and 913 healthy controls aged 16-80 years, the association between sunbed use and malignant melanoma was evaluated. A total of 250 (44%) cases and 372 (41%) controls reported ever having used sunbeds. A significantly elevated odds ratio for developing malignant melanoma after regular exposure to sunbeds was found, adjusted for hair colour, raised naevi, skin type and number of sunburns (odds ratio (OR) 1.8, 95% confidence interval (CI) 1.2-2.7). A dose-response relationship between total number of sunbed uses and melanoma risk was only found up to the level of 250 times. The OR was higher in individuals younger than age 36 years (adjusted OR 8.1, 95% CI 1.3-49.5 for regular vs. never use). The association seemed to be true only for subjects with black/dark brown or light brown hair and among females. Lesions of the extremities showed the strongest association of increased risk with sunbed use. An increased risk was related to commercial exposure and to exposure during the winter. The results substantiate the hypothesis that exposure to sunbeds might increase the risk of developing malignant melanoma.

Indoor tanning: risks, benefits, and future trends

The indoor tanning industry is a $1 billion-a-year business in the United States, and use of these high-intensity UVA tanning devices continues to grow. Many members of the medical community are concerned about the safety of these largely unregulated devices, but tanning salon operators state such concerns are unfounded and unproved. A comprehensive review of current knowledge of the operation and effects of indoor tanning is presented. The effects of UV radiation (especially UVA) on experimental animals and human beings are examined. Both acute and chronic effects are delineated from experimental sources as well as from epidemiologic studies and clinical observations. Existing safety regulations are described. Information on operator knowledge and compliance with existing safety regulations is reviewed.

Multiple lentigines confined to psoriatic plaques

The development of naevus spilus-like hyperpigmentation at sites of resolving plaques of psoriasis has been reported previously. Although the mechanism is not understood, PUVA therapy has been implicated in most cases. We report an additional case in which lentigines, confined to sites of resolving psoriasis, occurred following oral PUVA. We also describe similar clinical features in two patients who had not received PUVA, which strengthens the observation that this treatment is not a prerequisite for development of this unusual pattern of pigmentation.

Pigmented lesions as a sign of photodamage

Chronic exposure to ultraviolet (UV) radiation causes skin changes, known as photodamage. Apart from damage to the connective tissue of the dermis and to keratinocytes, pigmented lesions, known as 'age spots', occur. There are several types, but the most common lesions are the senile lentigines. The main differential diagnoses include reticular seborrhoeic keratosis and lentigo maligna, and histopathological examination is required for exact differentiation. Variants of lentigo senilis with acute onset after intense UV radiation are sunburn freckles. Psoralens- and UVA-induced freckles, and lentigines occur after phototherapy with artificial UV sources or use of sunbeds for cosmetic tanning. Ephelids are common genetically determined pigment spots appearing during childhood in a distinct photodistribution. Exposure to UV radiation also seems to play a role in the manifestation of acquired nevi. Since pigmented lesions in sun-damaged skin represent more than one entity, they differ in their response to treatment. This should be taken into account when the efficacy of topical therapy is evaluated.

North Carolina tanning operators: hazard on the horizon?

BACKGROUND

Previous small studies have demonstrated that operators of commercial tanning equipment may not be adequately trained. Most states have no training requirements for tanning operators. This study was designed to assess the medically relevant knowledge of cosmetic tanning salon operators and relate these to demographic variables.

METHODS

A written, anonymous questionnaire was distributed to 984 attendees of the first required operator training seminars conducted in North Carolina. Between July 1990 and June 1991, proprietors and their employees of the commercial tanning industry who attended these seminars were surveyed. No conference attendee refused to complete the questionnaire. Demographic information and responses to the medical information section of the questionnaire were scored by computer.

RESULTS

Important findings included that 71% of surveyed operators had never received any training for their current position. Operators of cosmetic tanning equipment were often unaware of contraindications to tanning such as photosensitizing drugs and specific medical conditions. Few operators recognized methoxsalen (26%) or trisoralen (34%) or their respective proprietary names as contraindications to tanning. Operator knowledge was not related to their educational achievement, previous tanning salon experience, or prior tanning industry-sponsored training. Children younger than 10 years old were tanned by 2.6% of the operators.

CONCLUSION

These data suggest that the public may be at risk for UV light-induced diseases and burns because of operator lack of knowledge.

Pigmentary changes of the ageing skin

In subjects older than 25-30 years the number of enzymatically active melanocytes detectable by the dopa reaction decreases by about 10-20% per decade, with exposed skin having approximately twice as many pigment cells as unexposed skin. Chronic exposure to sunlight may stimulate the epidermal melanocyte system rather than accelerating chronological ageing. The number of melanocytic naevi declines with age. Despite the decreased melanocyte density, photoaged skin has irregular pigmentation and, frequently, there is hyperpigmentation. This may be due to greater positivity of dopa of chronically irradiated melanocytes. Heterogeneity in skin colour in exposed areas of skin is due to uneven distribution of pigment cells, a local loss of melanocytes, and a modification in the interactions between melanocytes and keratinocytes. The most common pigmented lesions in sun-exposed skin include ephelides, actinic lentigo, pigmented solar keratoses and seborrhoeic keratoses, and lentigo maligna. The white spots in aged skin are usually stellate pseudoscars or idiopathic guttate hypomelanosis. Greying of the hair is due to progressive loss of melanocytes from the hair follicles. In vivo and in vitro studies are necessary to increase overall understanding of the processes involved and to improve treatment of the pigmentary changes in ageing skin.

Tanning-bed lentigines: ultrastructural and histopathologic features

The development of unusual melanocytic lesions after exposure to UVA tanning beds has been reported recently. We studied one such case with the use of light and electron microscopy and found the appearance similar to the lentigines that may occur after psoralen photochemotherapy. Histologically, some melanocytes showed mild nuclear atypia. Ultrastructural examination showed features similar to those of other forms of lentigo.

Possible ultraviolet A-induced lentigines: a side effect of chronic tanning salon usage

A patient who developed lentigines after prolonged ultraviolet A (UVA) exposure in a tanning booth is described. The patient had no exposure to psoralens or furocoumarins. Histologic examination of a representative lentigo revealed melanocytic hyperplasia and cytologic atypia. Increased nevocytic activity with histologic dysplasia was present in several junctional nevi excised during the period of UVA exposure. Several studies have revealed significant effects of UVA on melanocytes. Patients should be cautioned to avoid tanning bed use in view of these potentially deleterious effects.