Measurement and perception of skin colour in a skin cancer survey

Questionnaire items to assess skin color and erythemal sensitivity: reliability, validity, and "the dark shift"

BACKGROUND

Skin pigmentation is a key factor for UV radiation exposure related cancers. To appropriately target cancer control activities related to this exposure and for better representation in epidemiologic studies, a valid and reliable assessment of skin color is required.

METHODS

The validity and reliability of two self-report measures were assessed: skin color and erythemal sensitivity. A sample of 289 university students categorized their unexposed skin color and photosensitivity via a questionnaire. Skin color was also measured by spectrophotometer. After 7 days, participants repeated the self-report assessment.

RESULTS

Significant correlations were found for both self-report items with objective measures, indicating that these items may be valid assessment tools (color: Spearman's rho=-0.75, P<0.001; photosensitivity: Spearman's rho=-0.64, P<0.001). No sex differences in validity were evident. Stronger correlations were found among those of European than those of non-European ethnicity (color: Spearman's rho=-0.78 versus -0.59, bootstrap P=0.007; photosensitivity: Spearman's rho=-0.63 versus -0.28, bootstrap P=0.001). Strong biases toward overestimation of skin pigmentation were evident, ranging from 36% in the self-identified fair skin group to 77% in the medium skin color group. Intrarater reliability of the questionnaire items was high (color: k=0.78, P<0.001; photosensitivity: k=0.77, P<0.001).

CONCLUSIONS

Study findings suggest that self-report may be a valid measurement strategy when assessing skin type, but there is a bias toward overestimation of skin color and, potentially, UV radiation resilience.

IMPACT

This bias has the potential to undermine the effectiveness of skin cancer prevention efforts and needs to be addressed in health promotion programs.

[Behaviors related to sunlight exposure versus protection in a random population sample from 15 Brazilian State capitals and the Federal District, 2002-2003]

This article examines region-specific relations between prevalence of protection against sunlight and socio-demographic and behavioral variables in Brazil. Data were derived from a cross-sectional population-based random sample. Information on sunlight exposure was available for a total of 16,999 individuals 15 years and older. Comparing the North and South of Brazil, crude differences between women and men in the use of "sunscreen" and "protective headwear" were +10.9% (95%CI: 7.1; 14.6) and -11.6% (95%CI: -17.0; -6.3) in the North and +21.3% (95%CI: 17.7; 24.9) and -16.0% (95%CI: -20.2; -12.5) in the South. Adjusted differences by selected variables confirmed that women use more sunscreen protection and less headwear protection as compared to men in both the North and South, but the difference was not homogeneous by region (interaction term p value < 0.05).

Updates from the British Association of Dermatologists 86th Annual Meeting, 4?7 July 2006, Manchester, U.K

Here we provide a synopsis of the main clinical and research advances in clinical, epidemiological and biological dermatology that were presented at the meeting of the British Association of Dermatologists (BAD) held during 4-7 July 2006, in Manchester, U.K. Only the more important advances or summaries of findings are mentioned. The meeting was held at the Manchester International Conference Centre (Fig. 1). The annual dinner was held at Manchester Town Hall, in the Great Hall decorated with magnificent murals by Ford Madox Brown, with Dr Susan Burge as host.

Genetic and environmental influences on skin pattern deterioration

Sun exposure has been known to cause histological changes in the dermal layer of the skin. Using deterioration in the fine reticular patterning of the epidermal stratum corneum (skin pattern, as measured on the Beagley-Gibson scale) as a proxy measure of histological changes in the dermal layer, previous studies have typically assumed that degradation of skin pattern is largely caused by sun exposure. A twin study comprising 332 monozygotic twin pairs and 488 dizygotic twin pairs at ages 12, 14, and 16 was used to investigate the etiology of variation in skin pattern, particularly in relation to measured sun exposure and skin color. Our results indicate that although self-reported sun exposure is a significant contributor to variation in skin pattern, its effect is small, explaining only 3.4% of variation in skin pattern at age 14. Additive genetic effects explain 86% of variation in skin pattern at age 12 but these effects reduce with age so that 75% of variation is due to additive genetic effects at age 14 and 72% at age 16. This trend of diminishing genetic influences continues into adulthood, with 62% of variation due to non-additive genetic factors in a smaller adult sample (aged 32-86). Skin color explains 10.4% of variation in skin pattern at age 12, which is due to additive genetic influences common to both. Melanin content appears to provide a protective effect against skin pattern deterioration, perhaps because of the structural differences in melanosomes between different skin types or the free radical scavenging properties of melanin.

Health status and plasma dioxin levels in chloracne cases 20 years after the Seveso, Italy accident

BACKGROUND

The Seveso, Italy accident of 1976 exposed a large population to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or simply dioxin). The accident resulted, mostly among children, in one of the largest ever-reported outbreaks of chloracne, the typical skin disorder due to halogenated-hydrocarbon compounds.

OBJECTIVES

Approximately 20 years after the accident, we conducted an epidemiological study in Seveso to investigate (a) the health status of chloracne cases; (b) TCDD-chloracne exposure-response relationship; and (c) factors modifying TCDD toxicity.

METHODS

From 1993 to 1998, we recruited 101 chloracne cases and 211 controls. Trained interviewers administered a structured questionnaire assessing, among other epidemiological variables, information on an extensive list of diseases. During the interview, individual pigmentary characteristics were determined. We measured plasma TCDD levels using high-resolution gas chromatography/mass spectrometry.

RESULTS

Plasma TCDD was still elevated (> 10 ppt) in 78 (26.6%) of the 293 subjects with adequate plasma samples, particularly in females, in subjects who had eaten home-grown animals, and in individuals with older age, higher body mass index and residence near the accident site. After 20 years, health conditions of chloracne cases were similar to those of controls from the Seveso area. Elevated plasma TCDD was associated with chloracne [odds ratio (OR) = 3.7, 95% confidence interval (CI) 1.6-8.8, adjusted for age, sex and residence]. Chloracne risk was higher in subjects younger than 8 years at the accident (OR = 7.4, 95% CI 1.8-30.3) and, contrary to previous hypotheses, did not increase at puberty onset or in teenage years. Subjects with elevated TCDD levels and light hair colour had higher relative odds of chloracne (OR = 9.2, 95% CI 2.6-32.5).

CONCLUSIONS

Dioxin toxicity in chloracne cases was confined to the acute dermatotoxic effects. Chloracne occurrence appeared related to younger age and light hair colour. Age-related dioxin elimination or dilution must be taken into account in interpreting these results.

Longitudinal assessment of the nevus phenotype in a melanoma kindred

Phenotypic characteristics of members of a melanoma prone kindred with a V126D CDKN2A gene mutation were monitored over approximately 15 y. Thirty-eight previously studied subjects were recruited. Participants underwent a complete skin examination by the same dermatologist who examined them initially. The size and location of all nevi were recorded on a body map diagram. Total nevus number (TNN) and total nevus density (TND) were determined. CDKN2A sequencing verified 13 mutation carriers and 16 non-carriers. Nine participants were spouse controls without a history of melanoma and did not carry a CDKN2A mutation. Mutation carriers demonstrated a greater mean TNN and TND at initial and follow-up examinations compared with non-carriers and continued to develop nevi rather than show nevus regression seen in non-carriers and spouse controls. Non-carriers showed an intermediate nevus phenotype between mutation carriers and spouse controls. Four of the 13 mutation carriers and one non-carrier have developed invasive melanoma. Over a 15-y interval, TNN and TND were increased in mutation carriers compared with non-carriers and spouse controls. Continued accumulation of nevi in mutation carriers supports a nevogenic role for this CDKN2A mutation. An intermediate nevus phenotype in non-carrier family members suggests the presence of additional modifier genes.

Monitoring of nevus density in children as a method to detect shifts in melanoma risk in the population

BACKGROUND

Nevus density in children, a well-known risk factor for malignant melanoma, depends both on constitutional factors and on previous ultraviolet (UV) exposure. Secular trends of childhood UV exposure could thus be indirectly monitored by repeated standardized surveys assessing nevus density in children, such as the "childhood monitoring of nevus density (CMONDE-Study)".

METHODS

Two complete surveys comprising all children at the time of school enrolment were performed in the city and county of Göttingen, Germany, during the years 1999 and 2000. A total of 4252 children with a median age of 6.25 years were examined as part of the mandatory school enrolment health assessment, and complete data were available for 3881 children.

RESULTS

Median nevus density was 5.8/m(2) in the entire study group. The subgroup-specific median increased from "Fitzpatrick skin type" IV to II, but the density was not increased for the type I subgroup. Similarly, nevus density rose with increasing lightness of hair color, but was very low in red-haired individuals. While the number of freckles was also strongly associated with nevus density, the association between iris color and skin reflectance, respectively, was weak. The duration of the additional examination for CMONDE was on average 3-5 min per child.

CONCLUSION

We regard CMONDE as a highly feasible surveillance instrument, which should be implemented as an important addition to regular regional or national health reporting.

Misclassification due to body hair and seasonal variation on melanin density estimates for skin type using spectrophotometry

Recent advances have enabled quite accurate estimations of cutaneous melanin density by spectrophotometry using reflectance of light at wavelengths 400 and 420 nm. Our purpose was to assess the effect of body hair and seasonal variation at the upper inner arm and buttock on measurements of melanin density. We estimated melanin density of 104 volunteers at 3-monthly intervals over 12 months both before and after shaving. Removing body hair at the upper inner arm had no effect, but substantially reduced melanin estimates at the buttock in men. Significant seasonal variation was only observed at the upper inner arm, with highest readings in summer-autumn. In case-control studies, misclassification due to body hair at the buttock and seasonal variation at the upper inner arm could affect the observed odds ratio substantially. However, both sources of error can be reduced by careful attention to key aspects of study design.

Melanocortin-1 receptor genotype is a risk factor for basal and squamous cell carcinoma

MC1R gene variants have previously been associated with red hair and fair skin color, moreover skin ultraviolet sensitivity and a strong association with melanoma has been demonstrated for three variant alleles that are active in influencing pigmentation: Arg151Cys, Arg160Trp, and Asp294His. This study has confirmed these pigmentary associations with MC1R genotype in a collection of 220 individuals drawn from the Nambour community in Queensland, Australia, 111 of whom were at high risk and 109 at low risk of basal cell carcinoma and squamous cell carcinoma. Comparative allele frequencies for nine MC1R variants that have been reported in the Caucasian population were determined for these two groups, and an association between prevalence of basal cell carcinoma, squamous cell carcinoma, solar keratosis and the same three active MC1R variant alleles was demonstrated [odds ratio = 3.15 95% CI (1.7, 5.82)]. Three other commonly occurring variant alleles: Val60Leu, Val92Met, and Arg163Gln were identified as having a minimal impact on pigmentation phenotype as well as basal cell carcinoma and squamous cell carcinoma risk. A significant heterozygote effect was demonstrated where individuals carrying a single MC1R variant allele were more likely to have fair and sun sensitive skin as well as carriage of a solar lesion when compared with those individuals with a consensus MC1R genotype. After adjusting for the effects of pigmentation on the association between MC1R variant alleles and basal cell carcinoma and squamous cell carcinoma risk, the association persisted, confirming that presence of at least one variant allele remains informative in terms of predicting risk for developing a solar-induced skin lesion beyond that information wained through observation of pigmentation phenotype.

Melanocortin-1 receptor polymorphisms and risk of melanoma: is the association explained solely by pigmentation phenotype?

Risk of cutaneous malignant melanoma (CMM) is increased in sun-exposed whites, particularly those with a pale complexion. This study was designed to investigate the relationship of the melanocortin-1 receptor (MC1R) genotype to CMM risk, controlled for pigmentation phenotype. We report the occurrence of five common MC1R variants in an Australian population-based sample of 460 individuals with familial and sporadic CMM and 399 control individuals-and their relationship to such other risk factors as skin, hair, and eye color; freckling; and nevus count. There was a strong relationship between MC1R variants and hair color and skin type. Moreover, MC1R variants were found in 72% of the individuals with CMM, whereas only 56% of the control individuals carried at least one variant (P<.001), a finding independent of strength of family history of melanoma. Three active alleles (Arg151Cys, Arg160Trp, and Asp294His), previously associated with red hair, doubled CMM risk for each additional allele carried (odds ratio 2.0; 95% confidence interval 1. 6-2.6). No such independent association could be demonstrated with the Val60Leu and Asp84Glu variants. Among pale-skinned individuals alone, this association between CMM and MC1R variants was absent, but it persisted among those reporting a medium or olive/dark complexion. We conclude that the effect that MC1R variant alleles have on CMM is partly mediated via determination of pigmentation phenotype and that these alleles may also negate the protection normally afforded by darker skin coloring in some members of this white population.

Do all fair-skinned Caucasians consider themselves fair?

BACKGROUND

Fair skin color is a risk factor for skin cancer. We aimed to determine whether Caucasians have an accurate perception of their skin color.

METHODS

A convenience sample of 341 Caucasian adults in Townsville, Queensland, Australia was asked to categorize the color of their unexposed skin as fair, medium, or olive. Reflectance was measured on the inner upper arm (400-700 nm) for each subject to provide an objective measure of inherent skin pigmentation.

RESULTS

The median skin reflectances at 685 nm for the olive (68.7%), medium (68.9%), and fair (71.9%) perception groups were very similar and were within the reflectance range generally associated with a fair/light complexion (>/=67%). Of those with a skin reflectance >/=67%, 46.6% considered their skin medium or olive. Agreement between perceived and measured skin color was poor (kappa = 0.113), with 36.4% over-estimating and 16.4% under-estimating their skin's natural pigmentation.

CONCLUSIONS

Some Caucasians over-estimate their skin pigmentation and possibly the level of protection from sunlight this affords them. Skin cancer prevention campaigns that attempt to target those at greater risk of skin cancer, on the basis of fair/light skin color, are likely to fail, as many of these individuals don't consider themselves fair.

The prevalence and determinants of solar keratoses at a subtropical latitude (Queensland, Australia)

We report the association between skin pigmentation and individual sun exposure, and the occurrence of solar keratoses (SKs) in an unselected population, quantified for the first time. SKs were examined in a representative sample of 197 residents of the community of Nambour in Queensland, Australia. Estimates of sun exposure were combined with a measure of ultraviolet (UV) flux to estimate actual UV exposure, both occupational and recreational, during childhood and adult life. The number of episodes of painful sunburn was used as a measure of intermittent, intense UV exposure. Eight-three participants (43%) had at least one SK, while 35 (18%) had more than 10 SKs diagnosed. The age- and sex-adjusted odds ratios (ORs) for the development of SKs were higher in individuals with fair (OR = 14.1) or medium skin (OR = 6.5), compared with olive-skinned individuals. Individuals with poor ability to develop a suntan were similarly at increased risk compared with others. High levels of occupational UV exposure during adult life were confirmed as being strongly associated with prevalent SKs (OR = 2.4 for heavy/maximal adult exposure), with an even stronger association seen in those individuals with multiple SKs (OR = 4.3 for maximal adult exposure). Although no clear association was demonstrated between SK prevalence and accumulated childhood sun exposure, a history of even one episode of sunburn in childhood was strongly associated with SK prevalence (peak OR of 5.9 for one sunburn).

The measurement of constitutive and facultative skin pigmentation and estimation of sun exposure in Caucasians with basal cell carcinoma and cutaneous malignant melanoma

In two identical and simultaneously performed case-control studies of basal cell carcinoma (BCC) and cutaneous malignant melanoma (CMM) with age-matched, sex-matched and residence-matched controls, skin pigmentation was measured objectively by skin reflectance spectroscopy in 145 BCC patients and 174 matched controls and in 168 CMM patients and 176 matched controls. Measurements were performed at the forehead, the upper chest, the upper back, the lateral and medial aspects of the upper arm, and the buttocks. Self-estimation of sun exposure in childhood, in youth and in adulthood was performed by all subjects. There were no statistically significant differences in constitutive skin pigmentation at the buttocks between BCC patients and controls (P = 0.96) or between CMM patients and controls (P = 0.13). Facultative skin pigmentation in ultraviolet-exposed sites was not significantly different between BCC patients and controls except that women patients had higher pigmentation at the lateral side of the upper arm. For CMM, men patients had higher pigmentation at the lateral side of the upper arm. Self-estimations of sun exposure did not show differences between patients and controls but indicated high exposure levels in childhood and youth and in adult leisure time. Sun exposure estimated by increase in facultative pigmentation above the constitutive level (the Sun Exposure Index) was not significantly different between BCC patients and controls, whereas CMM men patients had higher estimates for the lateral side of the upper arm, the chest and the back.

The multicentre south European study 'Helios'. I: Skin characteristics and sunburns in basal cell and squamous cell carcinomas of the skin

The aim of this study was to investigate constitutional and environmental determinants of non-melanocytic skin cancer among different populations from south Europe. Between 1989 and 1993 we interviewed incident cases and a random population sample of controls from five centres where a cancer registry was operating, whereas we selected a sample of hospital-based cases and controls from three other centres. Controls were stratified according to the age and sex distribution of cases. In all, 1549 cases of basal cell carcinoma (BCC), 228 of squamous cell carcinoma (SCC) and 1795 controls were interviewed. Both cancers affected primarily sun-exposed sites such as face, head and neck, but the prevalence of BCC on the trunk was higher than for SCC. Pigmentary traits such as hair and eye colour as well as tendency to sunburn were strong and independent indicators of risk for both BCC and SCC. In SCC, adjusted odds ratios (ORs) ranged from 1.6 for fair hair colour to 12.5 for red hair. Light-blonde hair entailed a risk of about 2 for BCC. Pale eye colour was associated with a risk of 1.8 for SCC and 1.4 for BCC. Subjects who always burn and never tan showed an adjusted OR of 2.7 for BCC and 2.0 for SCC. A history of sunburns and a young age at first sunburn were associated with an increased risk for BCC only (OR 1.7). Pigmentary traits and sun sensitivity of the skin confirmed their role as risk indicators. The effect of sunburns, as an indicator of both exposure and sun sensitivity of the skin, is less clear. Nevertheless, its association with BCC suggests, by analogy with melanoma, a relationship with intense sun exposure. Conversely, SCC would require prolonged exposure to sunlight.

Non-melanoma skin cancer: an evaluation of risk in terms of ultraviolet exposure

A retrospective study of 143 patients histologically diagnosed with non-melanoma skin cancer (NMSC) was carried out in order to evaluate the influence of ultraviolet (UV) radiation on the appearance of more than one NMSC in the same person. Descriptive statistical and logistic regression analyses were carried out for each variable and its possible interaction, in order to determine the potential appearance of multiple NMSC. The results obtained were in agreement with those of earlier studies. A significant relationship was observed between occupational UV exposure and individuals with more than one NMSC. Those patients tended to be blue-eyed and were chronically exposed to UV radiation as a result of occupational activities (although not always in leisure activities); most did not take protective measures such as the use of hats or creams.

Premature ageing of the skin in a Queensland population

OBJECTIVE

To determine the prevalence of premature ageing of the skin and to assess its associations with skin cancer and related risk factors in a Queensland population.

DESIGN

Community-based prevalence survey of skin cancer and actinic skin damage.

SETTING

Population of Nambour, Queensland, in December 1986.

SUBJECTS

Random sample of 1539 residents aged 20 to 55 years for whom skin texture measurements were obtained, and a subsample of 807 whose skin reflectance was measured.

MAIN OUTCOME MEASURES

Associations of premature ageing of exposed skin, assessed by silicone moulds of the dorsal skin of the hand, with present or past skin cancer, skin colour measured by reflectance and other related risk factors.

RESULTS

Skin texture changes consistent with moderate to severe ageing were observed in 72% of men and 47% of women under 30 years of age. Severity of skin ageing was significantly associated with increasing age, and independently, with the presence of solar keratoses (P less than 0.01) and skin cancer (P less than 0.05). Increased deterioration was also correlated with decreasing reflectance (darker colour) of sun-exposed skin in both men (P less than 0.01) and women (P less than 0.05), but not with reflectance from sun-protected skin, that is inherent skin colour. Photoageing among men was associated with outdoor occupations, outdoor leisure activities, a tendency to sunburn and previous skin cancer.

CONCLUSIONS

Marked premature ageing of exposed skin is common in residents of Queensland and is evident among adults in their twenties. Public education programs about the ill-effects of excessive sun exposure should emphasise not only the risk of skin cancer, but also the high risk of premature skin ageing.

Photoprotection by melanin

This paper is an attempt to summarize the current state of information on melanin and epidermal melanin pigmentation (EMP) as photoprotective agents. The chemistry and biochemistry of melanin (the particle) and its interaction, in its various forms, with UV radiation are considered. Methods of attenuation of UV radiation are discussed in terms of structure and chemical constituents. Photoprotection by constitutive and facultative pigmentation is reviewed with minimum erythema dose (MED) as the end point. The issue of acclimatization to UV radiation is discussed in terms of UVB phototherapy for psoriasis. Finally, skin cancer is considered as an end point and the reduction of its incidence with pigment level is discussed. It is concluded that whilst EMP provides protection, its extent depends on the end point chosen for evaluation. MED is a convenient photobiological end point but is rather insensitive, whereas skin cancer is sensitive but impractical for laboratory studies. Our current state of knowledge of melanin lacks information on its absorption and scattering coefficients and its refractive index. Methods for the quantitative measurement of EMP are also urgently required.