Does intermittent sun exposure cause basal cell carcinoma? a case-control study in Western Australia

Site-specific occurrence of nonmelanoma skin cancers in patients with cutaneous melanoma

In a registry-based case–control study, we compared the site-specific occurrence of nonmelanoma (keratinocytic) skin cancers among patients with cutaneous melanoma cases (cases, n=3774) and solid tumours (controls, n=349 923), respectively. Overall, patients with melanoma were almost five-fold more likely to develop keratinocytic cancers compared with solid tumour controls (adjusted OR 4.7, 95% CI 4.1–5.3), but the risks varied depending upon the site of melanoma. Whereas patients with melanoma of the head and neck had similarly increased risks of keratinocytic cancers across all body sites, patients with melanoma of the trunk were significantly more likely to develop keratinocyte cancer diagnosed on the trunk (adjusted OR 12.5, 95% CI 7.2–20.2) than on the head and neck (adjusted OR 3.0, 95% CI 2.2–4.3). Similar colocalisation of skin tumours was observed for patients with melanomas of the lower limb. These findings provide support for the hypothesis that skin cancers at different anatomical sites may arise through different causal pathways.

Reliability and Validity of a Telephone Questionnaire for Estimating Lifetime Personal Sun Exposure in Epidemiologic Studies

Our Australia-wide case-control study of ocular melanoma diagnosed in 1996 to 1997 needed a short telephone interview on sun exposure. We constructed one by examining data from 700 controls ages 40 to 64 years in the Geraldton Skin Cancer Survey in 1988; they had answered a "whole-of-life" questionnaire in a face-to-face interview. Sun exposure in their first 4 decade years of age best predicted their lifetime annual average sun exposure, so the shortened questionnaire asked about sun exposure in these 4 decade years only. Retesting 60 participants 1 year later with the whole-of-life questionnaire gave an intraclass correlation coefficient of 0.65 (95% confidence interval, 0.48-0.78) for ranked total sun exposure between the two interviews; the intraclass correlation coefficient was higher in men (0.73) than in women (0.54). Correlations were also high between parallel measurements of sun exposure on working days in the decade years and in outdoor occupations throughout life in the telephone interview of the ocular melanoma study (Spearman's R = 0.75) and in another study of non-Hodgkin's lymphoma (R = 0.71). Agreement between simultaneous parallel measures of total exposure (nonworking + working day and recreational + occupational exposure) was slightly weaker and of nonworking day and recreational exposure much weaker. Occupational exposure in women was much less strongly correlated with total exposure than it was in men possibly because of their frequently combined work and family roles, which the questionnaires did not try to separate. Research is needed into how this might be done to improve sun exposure measurement in women.

Basal cell carcinoma of the eyelid in Finland during 1953−97

PURPOSE

To study the incidence of basal cell carcinoma (BCC) of the eyelid in Finland.

METHODS

We studied 6241 cases of BCC of the eyelid reported to the nationwide Finnish Cancer Registry during 1953-97. We determined the age- and sex- specific incidence rates and overall rates adjusted for age to the world standard population, and social class- and occupation-specific standardized incidence ratios, with the total Finnish population as reference.

RESULTS

The incidence rates of BCC of the eyelid varied between 0.7 and 3.0 per 100 000 person-years in men and between 0.5 and 2.8 per 100 000 person-years in women during the study period. The age-adjusted incidence rates of BCC of the eyelid increased during 1953-87 (p < 0.0001). The incidence of BCC of the eyelid rose significantly with age. There were no significant differences in standardized incidence ratios (SIRs) for BCC of the eyelid between different social class and occupation categories.

CONCLUSION

Age-adjusted incidence rates showed that BCC of the eyelid was more than twice as frequent during 1978-97 than before 1968. Ageing may partly explain the increased incidence of BCC of the eyelid, whereas there were no differences in the SIRs for BCC of the eyelid between different social class and occupation categories in Finland.

Basal Cell Carcinomas of the Eyelids

Basal cell carcinomas (BCC) are the more frequent malignant tumors seen in France as in other western countries. They represent 20% of eyelid tumors and 90% of eyelid malignancies. Due to their local growth, problems may arise when treating BCC, and curative exeresis must be the preferred choice each time it is possible. BCC of the eyelids have a high risk of recurrence. Recurrences are more aggressive, infiltrative and destructive and have a considerably poorer rate of cure than primary tumors. Eyelid reconstructions can entail use of complex methods which should only be carried out by a trained ophthalmologist who is also able to treat any associated age-related ocular pathologies. BCC is the most common cause leading to eyelid reconstructive surgery; a surgery which has a triple objective: tumor removal, functionality and an esthetic outcome.

Associations between ultraviolet radiation, basal cell carcinoma site and histology, host characteristics, and rate of development of further tumors

BACKGROUND

Patients with basal cell carcinoma (BCC) frequently develop further tumors during follow-up.

OBJECTIVE

We sought to elucidate the relative effects of pattern of ultraviolet radiation exposure, and site and histologic type of the first tumor, on the rate of increase in BCC numbers.

METHODS

We used negative binomial regression analysis to study the association of selected variables on the rate of increase in BCC numbers in 266 Caucasian patients who first presented with a tumor on the head/neck or trunk with nodular or superficial histology.

RESULTS

Patients with an initial truncal BCC with superficial histology demonstrated significantly faster increases in BCC numbers than did patients with other site and histology combinations.

CONCLUSIONS

These data indicate that site and histology define subsets of patients with BCC.

Interleukin-6 induced basic fibroblast growth factor-dependent angiogenesis in basal cell carcinoma cell line via JAK/STAT3 and PI3-kinase/Akt pathways

We have previously demonstrated a xenograft of interleukin-6 (IL-6) overexpressing basal cell carcinoma (BCC) cell line induced tumors with high vasculature in nude mice. Here we asked whether IL-6 could induce angiogenic activity in BCC cell line. Tenfold concentrated conditioned medium (CM) from IL-6 overexpressing BCC cells exhibited higher angiogenic activities in chorioallantoic membrane and Matrigel plug assays, when compared with CM from vector control or parental BCC cells. The level of basic fibroblast growth factor 2 (bFGF) mRNA and secreted bFGF increased in IL-6 overexpressing BCC cells as shown by RT-PCR and ELISA, respectively. Concordantly, recombinant IL-6 treatment caused the elevation of bFGF mRNA and protein levels in parental BCC cells in a time-dependent manner. Neutralizing bFGF function by anti-bFGF antibody significantly inhibited CM-induced human umbilical vein endothelial cells (HUVEC) tube formation and Matrigel plug formation. Meanwhile, cyclooxygenase 2 (COX-2)-specific siRNA markedly abolish HUVEC tube formation. These data indicated both bFGF and COX-2 play an essential role for IL-6-induced angiogenesis in BCC cell line. Treatment with AG490 (Janus tyrosine kinase [JAK] inhibitor) and LY294002 (PI3-Kinase inhibitor) inhibited IL-6-mediated upregulation of bFGF mRNA and protein secretion. Consistently, transfection with dominant negative mutants of signal transducer and activator of transcription 3 (STAT3) and acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt) effectively abolished IL-6-mediated expression of bFGF mRNA and protein. Our data suggest that under in vitro experimental condition, bFGF and COX-2 are downstream effectors of IL-6-induced angiogenic activity in BCC cell. The IL-6-mediated bFGF upregulation is through activation of JAK/STAT3 and PI3-Kinase/Akt pathways.

Etiologic factors associated with p53 immunostaining in cutaneousmalignant melanoma

Findings from a case-control study of cutaneous malignant melanoma (CMM) in Queensland, Australia, suggest that melanomas exhibiting p53 immunostaining possess different risk factors from those of other melanomas. To further explore this hypothesis, a case-only analysis of risk factors for p53 immunostaining with anti-p53 MAb DO-7 was undertaken in 523 people diagnosed with CMM in Canada and Australia. Phenotypic factors and past sun exposure were measured using a self-administered questionnaire and telephone interview. The presence of strong p53 staining (>10% of cell nuclei positively stained vs. <1% staining) was positively associated with some indicators of high cumulative sun exposure: lentigo maligna melanoma subtype (OR = 3.2 vs. superficial spreading subtype), melanoma location on the head and neck (OR = 2.8 vs. back), histopathologic evidence of solar elastosis (OR = 2.1) and previous diagnosis of nonmelanoma skin cancer (OR = 2.4). Strong staining was negatively associated with high nevus density on the back (OR = 0.2 for >25 nevi vs. 0-3 nevi) and histologic evidence of a coexisting nevus (OR = 0.3). Other factors associated with strong p53 immunostaining include greater Breslow thickness (OR = 7.4 for >4.00 vs. <0.76 mm), male sex (OR = 2.2) and dense freckling (OR = 6.6 vs. few freckles). Of these, thickness, male sex, dense freckling, low nevus density on the back, histologic subtype and history of nonmelanoma skin cancer appeared to be independently associated with strong p53 staining. Our findings are consistent with the Queensland study in suggesting that variables indicating high accumulated sun exposure are positively associated with p53 staining and that an increased number of nevi is positively associated with its absence; they may reflect etiologic and pathogenetic heterogeneity in melanoma.

Web-Based Strategies to Disseminate a Sun Safety Curriculum to Public Elementary Schools and State-Licensed Child-Care Facilities

The Sunny Days, Healthy Ways curriculum, which has been effective in previous trials, was disseminated to public elementary schools (n=2,030) and state-licensed child-care facilities (n=3,755) in 4 states. Two Web sites were created, varying in the amount and type of information. Mailings referred principals and directors to the sites. Overall 117 unique users made 172 visits to the sites. More repeat visits were made to the enhanced than to the basic site (p=.04). In a survey, 20.0% of principals and directors recalled receiving the mailings and 80.9% of these read them. Web-based strategies were weak, but the low response rate may be typical for such marketing. They will require supplementation by more personal approaches.

Basal cell carcinoma: from host response and polymorphic variants to tumour suppressor genes

The molecular factors and events that characterize susceptibility and outcome in cutaneous basal cell carcinoma (BCC) have been the focus of much research interest. As a result, we are beginning to understand the complex relationships between exposure to ultraviolet radiation (UVR), host response and the resulting damage to key genes that characterize these tumours. In this review, we will focus on genetic factors that influence susceptibility and outcome. While the search for susceptibility genes has generally resulted in the identification of low penetrance allelic variants, studies on modifier genes influencing outcome variables such as tumour number, age of onset and tumour subtype have identified factors with higher potential impact. Here we will briefly describe some recent work on the genetic basis of the immune response to UVR, the effect of UVR on the generation of reactive oxygen species and their detoxification, and the role of onco- and tumour suppressor genes. Areas for further research are highlighted, together with a consideration of possible applications in clinical practice.

Perspectives in melanoma prevention: the case of sunbeds

The incidence of cutaneous malignant melanoma (melanoma) and of basal cell carcinoma is still increasing in most fair-skinned populations. The fashion of intermittent exposure to solar ultraviolet (UV) radiations is considered the main cause of this increase. In 20 years time, tan acquisition through exposure to artificial sources of UV radiations has become frequent among fair-skinned adolescents and young adults. Modern sunbeds are powerful sources of UV radiations that do not exist in the nature, and repeated exposures to high doses of UVA constitute a new phenomenon in humans. A large prospective cohort study on 106,379 Norwegian and Swedish women conducted between 1991 and 1999 has provided evidence for a significant, moderate increase in melanoma risk among regular sunbed users. Failure of past case-control studies to document with consistency the sunbed-melanoma association was probably due to a too short latency period between sunbed use and melanoma diagnosis, and to too few subjects with high total durations of sunbed use. Regulations of sunbed installation, operation and use should become standardised across the 25 European Union countries. Enforcement of regulations in tanning parlours remains inadequate. In contrast, the existence of regulations is presented by many tanning salon operators as a guarantee that sunbed use is safe. We stress the need for the control of information disseminated by the "tanning industry" on suppositions that sunbed use is safer than sun exposure, and on the hypothetical health benefits of tanning. New fluorescent UV lamps are proposed that have a spectrum similar to the midday sun. Given the known association between intermittent sun exposure and melanoma, public-health authorities should reconsider the soundness of the commercialisation of these lamps.

Interventions to prevent skin cancer by reducing exposure to ultraviolet radiation: a systematic review

The relationship between skin cancer and ultraviolet radiation is well established. Behaviors such as seeking shade, avoiding sun exposure during peak hours of radiation, wearing protective clothing, or some combination of these behaviors can provide protection. Sunscreen use alone is not considered an adequate protection against ultraviolet radiation. This report presents the results of systematic reviews of effectiveness, applicability, other harms or benefits, economic evaluations, and barriers to use of selected interventions to prevent skin cancer by reducing exposure to ultraviolet radiation. The Task Force on Community Preventive Services found that education and policy approaches to increasing sun-protective behaviors were effective when implemented in primary schools and in recreational or tourism settings, but found insufficient evidence to determine effectiveness when implemented in other settings, such as child care centers, secondary schools and colleges, and occupational settings. They also found insufficient evidence to determine the effectiveness of interventions oriented to healthcare settings and providers, media campaigns alone, interventions oriented to parents or caregivers of children, and community-wide multicomponent interventions. The report also provides suggestions for areas for future research.

Associations between UVR exposure and basal cell carcinoma site and histology

While sunlight is critical in basal cell carcinoma (BCC) pathogenesis the relationship between exposure and tumor site and histology is unclear. We determined if tumor site (trunk or head/neck) or histology (nodular or superficial) is determined by exposure pattern. In 66 cases with truncal and 362 patients with head/neck BCC at first presentation, average hours exposure/year, intermittency score, childhood sunburning and skin type were not significantly associated with tumor site or histology. However, often sunbathing was associated with a five-fold increased risk of truncal BCC. Average sunbathing score was significantly greater in 22 cases with truncal compared with 325 cases with head/neck nodular tumors and also in 44 cases with superficial truncal compared with superficial head/neck BCC. Thus, sunbathing determined tumor site but not histology.

Counseling parents and children on sun protection: a national survey of pediatricians

OBJECTIVE

To describe pediatricians' attitudes toward skin cancer (SC), sun protection (SP) counseling, and the quantity and content of such counseling and to identify barriers to counseling.

METHODS

An American Academy of Pediatrics Periodic Survey was mailed to 1616 randomly selected US members between October 2001 and February 2002. The response rate was 54.6%.

RESULTS

More than 90% of pediatricians agreed that SC is a significant public health problem and that preventing episodic high exposures to the sun during childhood will reduce the risk of adult melanoma. However, only 22.3% of respondents reported counseling most patients in all age groups. Female pediatricians were more likely to counsel most patients; pediatricians located in the South and West and those who practice in hospital/clinic settings were least likely to counsel compared with those in other regions. Approximately half (53%) of pediatricians reported selectively counseling on the basis of patient characteristics The most important SP recommendation named was using a sunscreen with a sun protection factor > or =15. Only 38% of pediatricians rated SP as very important to their patients' health compared with other topics such as use of car seats (86%), nutrition (79%), immunization issues (76%), and smoking/avoidance of environmental tobacco smoke (74%). The most frequently named barrier to SP counseling was lack of time (58% reporting).

CONCLUSIONS

Although the majority of pediatricians believe that SC prevention is a worthy issue, only a minority reported providing routine SP counseling to most patients in every age group, and most ranked SP lower in importance than other issues. Interventions might include programs and materials to educate patients and pediatricians alike. To have an effect on increasing rates of SC and SC mortality, a broader public health approach is needed as a complement to pediatricians' counseling efforts.

Rapid and Continuous Increases in Incidence Rates of Basal Cell Carcinoma in the Southeast Netherlands Since 1973

This study is aimed to determine the characteristics of the trends in incidence of basal cell carcinoma (BCC) in the Netherlands. We used incidence data of BCC from the Eindhoven Cancer Registry (Comprehensive Cancer Centre South) in the south of the Netherlands from 1973 to 2000. Data were age-adjusted and age-specific rates were calculated. Joinpoint and age-period-birth cohort modelling were applied. Between 1973 and 2000, age-adjusted incidence rates of BCC increased in both sexes, most markedly among (young) females. Recent increases were most marked on the trunk. The male data fitted age-drift models, suggesting a linear increase in rates over time, not attributable to either period- or cohort effects. In females, age-cohort-drift models described the data adequately, suggesting changes in intermittent UV exposures in subsequent cohorts. Incidence of BCC in the Netherlands is increasing rapidly, especially at body sites that are not chronically exposed to sunlight. The most likely explanation is an increased intermittent overexposure to UV radiation. This could have introduced an equal fractional increase in risk at all ages in all cohorts. There is no indication of an end to this trend in BCC.

Risk and protective factors for sporadic basal cell carcinoma: results of a two-centre case-control study in southern Germany. Clinical actinic elastosis may be a protective factor

BACKGROUND

There are very few data regarding sun exposure behaviour of patients with basal cell carcinoma (BCC) in central Europe.

OBJECTIVES

A case-control study of patients with sporadic BCC was conducted to assess the risk of occupational and leisure-time sun exposure behaviour, precursor lesions for skin cancer and phenotypic factors on the development of sporadic BCC in Ulm and Dresden, Germany.

METHODS

A comparison was made of 213 patients with BCC (128 from Ulm, 85 from Dresden; 103 men and 110 women; median age at diagnosis 69 years) and 411 controls (237 from Ulm, 174 from Dresden; 197 men and 214 women; median age 58 years). Crude odds ratios (ORs) and corresponding 95% confidence intervals for all of 64 possible risk factors revealed strong associations in 33 items. Selection of important risk factors was performed in a multiple logistic regression.

RESULTS

For sporadic BCC, an increased risk was shown for persons with actinic cheilitis (OR 7.1), actinic keratosis (OR 2.7) and solar lentigo (OR 2.5). The only phenotypic factor indicating risk of sporadic BCC was hair colour, with a higher risk for red/fair than brown/black hair (OR 4.3). There was an increased risk for persons with BCC in first-degree relatives (OR 5.1) and those with sunburn 20 years before sporadic BCC was diagnosed (OR 3.6). Additionally, occupational ultraviolet (UV) exposure appeared to be a risk factor (OR 2.4). In contrast, clinical actinic elastosis showed a protective effect (OR 0.1).

CONCLUSIONS

In contrast to earlier reports, clinical actinic elastosis turned out to be the only protective factor for sporadic BCC. A special relationship between wrinkling and BCC risk could not be shown. For basic research, future work should be aimed at elucidating further the different forms of collagen repair processes after intermittent and/or chronic UV exposure. The data strongly support the recommendation that a change in recreational UV exposure habits in individuals, and sunburn avoidance in particular, are necessary not only because of the increased long-term risk of melanoma, but also because of the risk of other skin cancers such as sporadic BCC.

Cancer control in women. Update 2003

The global cancer burden in women appeared to be increasing quickly at the end of the twentieth century with notable increases in the absolute numbers of cases of breast, cervix, lung and colorectal cancer of concern. However, prospects for cancer control in women appear to be good within our current knowledge and deserve close attention. Rates of lung cancer in women are increasing substantially in many countries and seem set to overtake breast cancer as the commonest form of cancer death in women in many parts of the world. These changes are due to the effects of cigarette smoking, a habit which women widely embraced during the second half of the last century. The high levels of smoking current in young women, which have yet to have their full inpact on death rates, constitute an important hazard not only for future cancer risks but for several other important causes of death. Although the breast is the commonest form of cancer in women in most western countries, the etiology of this disease remains elusive and preventable causes remain to be identified. Endogenous hormones also appear to have a role in cancer risk in women: oral contraceptives seem to increase slightly the risk of breast cancer in users in the use, and in the immediate post-use, period, but ten years after cessation the risk returns to that of never users. Oral contraceptive usage also appears to be protective against ovarian and endometrial cancer. The use of Hormonal Replacement Therapy (HRT) appears to increase the risk of endometrial cancer and a positive association with breast cancer risk appears to exist. Within the current knowledge of the epidemiology of cancer in women, the most important Cancer Control strategy is the prevention of cigarette smoking and the increase in the prevalence of adult women quitting smoking. Screening has also shown to be effective in reducing incidence and mortality of cervix cancer and mortality from breast and colorectal cancer. Although more work is needed, it is becoming clear that there could be an important role of HPV testing to further enhance cervix cancer screening.

Basal cell carcinoma of the maxillofacial region: site distribution and incidence rates in Arab/Jordanians, 1991 to 2000

PURPOSE

We sought to estimate the incidence rates and disease trends for basal cell carcinoma (BCC) of the maxillofacial region in the civilian population in the north of Jordan.

METHODS

A retrospective study was undertaken of all BCCs of the maxillofacial region diagnosed at the Regional Histopathology Department during the period 1991 to 2000.

RESULTS

The age-adjusted rate for BCC in 1992 was 6.3:100,000, and in 2000, it was 8.8:100,000. However, several disease trends were observed during the study period. Age- and gender-specific incidence rates apparently increased during the study period. Lesions were most commonly seen on the nose, facial skin, and periorbital skin. The proportions of BCC in the various anatomic sites that were reviewed remained fairly constant over the 10-year period.

CONCLUSIONS

In comparison with populations from other geographic areas, the incidence of BCC in the north of Jordan is low. Further studies are needed to identify behavioral and environmental factors that contribute to the development of BCC and to determine whether changes in diagnostic practices could account for the apparent rise in the incidence of this tumor in this population in recent years.

PTCH polymorphism is associated with the rate of increase in basal cell carcinoma numbers during follow-up: preliminary data on the influence of an exon 12-exon 23 haplotype

After first presentation with a basal cell carcinoma (BCC), patients demonstrate interindividual diversity in the rate of development of further BCCs (number/year of follow-up). The mechanism for this variation is unknown. In this study, we evaluated whether PTCH variants mediate this phenomenon. We used negative binomial regression analysis to identify associations between BCC numbers/year and host characteristics, parameters of exposure to ultraviolet radiation (UVR), and PTCH exon 12(1686) C/T, intron 15(2560+9) G/C, and exon 23(3944) C/T genotypes and haplotypes in 279 BCC cases who presented with an initial tumor on the head/neck. PTCH genotypes were not significantly associated with BCCs/year, although cases with two copies of the C1686-C3944 haplotype developed significantly fewer BCCs/year than those without this haplotype (rate ratio = 0.44; 95% CI = 0.27-0.71). Cases with one copy of T1686-T3944 developed more BCCs/year (rate ratio = 2.46; 95% CI = 1.27-3.97) than those without the haplotype. We found no significant associations between BCCs/year and the other PTCH haplotypes studied. We reexamined the association of C1686-C3944 with BCCs/year in a model that included UVR exposure parameters (sunburning in childhood, sunbathing score, intermittency of exposure between 40 and 60 years of age, exposure in hours/year) and skin type, gender, and age at first presentation. The association between C1686-C3944 and BCCs/year remained significant (rate ratio = 0.44; 95% CI = 0.26-0.73 for two copies of the haplotype). The data show that allelic variation in PTCH contributes to the rate of development of BCC.

Sun exposure may protect against non-Hodgkin lymphoma: A case-control study

Ultraviolet radiation is a hypothesised risk factor for non-Hodgkin lymphoma (NHL) but no epidemiological study has examined this association using direct measures of sun exposure in individuals. Adults aged 20-74 years living in NSW and ACT, Australia, were the study population. Cases (704 of 829 invited to take part, 85%) were diagnosed January 2000 to August 2001. Controls (694 of 1,136 invited to take part, 61%) were randomly selected from state electoral rolls and frequency-matched to cases by age, sex and state of residence. A self-administered questionnaire and telephone interview measured outdoor hours on working and nonworking days and vacations at 10, 20, 30, 40, 50 and 60 years of age. Logistic regression models of NHL and sun exposure contained the 3 matching variables, ethnicity and sun sensitivity measures as covariates. Contrary to expectations, risk of NHL fell with increasing reported sun exposure hours. Relative to 1.0 for the lowest quarter of total sun exposure hours, the odds ratios (ORs) for successively higher quarters were 0.72 (95% CI 0.53-0.98), 0.66 (0.48-0.91) and 0.65 (0.46-0.91) (p(trend)=0.01). The association of sun exposure on nonworking days with NHL was stronger; OR for highest quarter 0.47 (0.34-0.66) (p(trend)=0.0001). Risk also fell with sun exposure on vacations; OR for highest quarter 0.60 (0.43-0.85) (p(trend)=0.003). These associations appeared strongest in women and in childhood. There was little evident trend in risk with exposure on working day. Our results provide strong statistical evidence for an inverse association between sun exposure and NHL. Increasing evidence that vitamin D may protect against cancer makes UV-mediated synthesis of vitamin D a plausible mechanism whereby sun exposure might protect against NHL.

Correlates of sunburn experiences among U.S. adults: results of the 2000 National Health Interview Survey

OBJECTIVE

The purpose of this study was to determine the rate of sunburns in the U.S. adult population and the correlates of sunburns.

METHODS

Data from the 2000 National Health Interview Survey Cancer Control Module were used to calculate the number of sunburns (0, 1, 2, or > or = 3) experienced during the past year by age, sex, race/ethnicity, and skin sensitivity to sun exposure. The relationship between no sunburns vs. one or more sunburns and additional demographic, health, and behavioral factors for adults who self-identify as white Hispanic or white non-Hispanic was assessed using general linear contrasts. Multivariate logistic regression modeling was conducted to determine the most important covariates associated with sunburns. All analyses were weighted for the complex sampling design.

RESULTS

The study data suggest that overall, 18.5% (95% confidence interval [CI] 17.9, 19.1) of U.S. adults experience one sunburn a year, 9.7% (95% CI 9.3, 10.1) experience two, and 8.0% (95% CI 7.6, 8.4) experience > or = 3 sunburns. The data also indicate that adults who self-identify as white non-Hispanic experience sunburns more frequently than (in order of prevalence) those who identify as American Indian/Alaska Native, white Hispanic, Asian/Pacific Islander, or black. Sunburns were found to be more common among men than among women, more common among younger age groups than among older age groups, and more common among those with skin more prone to sunburn than among those with skin less prone to sunburn. Among individuals who self-identify as white Hispanic or white non-Hispanic, protective behaviors associated with lower rates of one or more sunburns in multivariate analyses are staying in the shade (odds ratio [OR] 0.73, 95% CI 0.66, 0.80) and wearing long-sleeved shirts (OR 0.86, 95% CI 0.75, 0.99).

CONCLUSIONS

Many American adults have one or more sunburns per year. Methods to protect from sun exposure may not be used as needed to prevent sunburn.

Correlates of sunburn experiences among U.S. adults: results of the 2000 National Health Interview Survey

OBJECTIVE

The purpose of this study was to determine the rate of sunburns in the U.S. adult population and the correlates of sunburns.

METHODS

Data from the 2000 National Health Interview Survey Cancer Control Module were used to calculate the number of sunburns (0, 1, 2, or > or = 3) experienced during the past year by age, sex, race/ethnicity, and skin sensitivity to sun exposure. The relationship between no sunburns vs. one or more sunburns and additional demographic, health, and behavioral factors for adults who self-identify as white Hispanic or white non-Hispanic was assessed using general linear contrasts. Multivariate logistic regression modeling was conducted to determine the most important covariates associated with sunburns. All analyses were weighted for the complex sampling design.

RESULTS

The study data suggest that overall, 18.5% (95% confidence interval [CI] 17.9, 19.1) of U.S. adults experience one sunburn a year, 9.7% (95% CI 9.3, 10.1) experience two, and 8.0% (95% CI 7.6, 8.4) experience > or = 3 sunburns. The data also indicate that adults who self-identify as white non-Hispanic experience sunburns more frequently than (in order of prevalence) those who identify as American Indian/Alaska Native, white Hispanic, Asian/Pacific Islander, or black. Sunburns were found to be more common among men than among women, more common among younger age groups than among older age groups, and more common among those with skin more prone to sunburn than among those with skin less prone to sunburn. Among individuals who self-identify as white Hispanic or white non-Hispanic, protective behaviors associated with lower rates of one or more sunburns in multivariate analyses are staying in the shade (odds ratio [OR] 0.73, 95% CI 0.66, 0.80) and wearing long-sleeved shirts (OR 0.86, 95% CI 0.75, 0.99).

CONCLUSIONS

Many American adults have one or more sunburns per year. Methods to protect from sun exposure may not be used as needed to prevent sunburn.

Differential effects of UV irradiation on nuclear retinoid receptor levels in cultured keratinocytes and melanocytes

A major risk factor for skin cancer is UV irradiation, which not only damages DNA and other photosensitive compounds like vitamin A, but may also perturb cellular signaling, e.g. via the retinoid receptor system believed to be important for cancer protection. We used cultured normal human keratinocytes and melanocytes to examine the effects of UV irradiation on the expression of the predominant retinoid receptors in the human skin (RARalpha, RARgamma and RXRalpha) and the AP-1 protein c-Jun; mRNA levels were studied by real-time PCR and protein levels by Western blot. In keratinocytes, a single dose of UVB (50 mJ/cm2) caused a rapid drop in the expression of all three receptors (mRNA levels minus 35-50% after 4 h; protein levels minus 20-45% after 8 h), which was followed over the next 40 h by a variable response, leading to full normalization for RARalpha only. In contrast, the levels of c-Jun did not change significantly after UV exposure. In melanocytes, UVB caused a similar drop of the retinoid receptor levels as in keratinocytes but this was soon followed by an increased expression leading to a complete normalization of all receptor levels within 1-3 days. The c-Jun levels in melanocytes increased 1 day after UV exposure and remained high (plus 50%) thereafter. In both cell types, a approximately 3-fold increase in apoptosis (measured by DNA fragmentation) was observed 8-48 h after UVB irradiation. In conclusion, a depletion of vitamin A and retinoid receptors by UV irradiation, together with unchanged or even increased c-Jun levels, might seriously interfere with retinoid signaling and thus promote future tumor development, especially in keratinocytes.

Factors associated with nonmelanoma skin cancer following renal transplantation in Queensland, Australia

BACKGROUND

Caucasian renal transplant recipients living in Queensland, Australia, have the highest risk of nonmelanoma skin cancer in the world.

OBJECTIVE

To determine clinical and environmental factors associated with posttransplantation nonmelanoma skin cancer in Queensland.

METHODS

361 Caucasian adult recipients completed a structured interview and full skin examination. Skin cancer details were obtained from hospital records.

RESULTS

Squamous cell carcinoma was strongly associated with blue or hazel eyes, time resident in a hot climate, and pretransplantation squamous cell carcinoma; tumor numbers were associated with birth in a hot climate, childhood sunburn, pretransplantation actinic keratoses, and smoking. The risk of basal cell carcinoma was strongly associated with acute or intermittent sun exposure during childhood and pretransplantation basal cell carcinoma; numbers were associated with blue or hazel eyes, time spent living in a hot climate, and male gender.

CONCLUSION

Clinical and environmental factors can be used to identify recipients at risk of nonmelanoma skin cancer in Queensland.

Lifestyle differences in twin pairs discordant for basal cell carcinoma of the skin

BACKGROUND

Basal cell carcinoma (BCC) of the skin is a multifactorial disease with a complex interplay of genetic, environmental and lifestyle factors, including patterns of solar exposure, with childhood exposure being of particular relevance. Case-control studies in disease-discordant twin pairs adjust for familial factors and improve the power of conventional case-control studies.

OBJECTIVES

To investigate the roles of sociodemographic, dietary, medication, hormonal and other lifestyle factors in the aetiology of BCC.

METHODS

The study base comprised all same-sex twins who had answered the baseline health questionnaire of the Finnish Adult Twin Cohort Study in 1975. Information on all histologically confirmed cases of BCC was retrieved from the nationwide cancer registry. The first twin to have BCC was defined as the case and his/her co-twin (alive at the time of diagnosis) as the control. Only pairs with the first BCC between 1976 and 1999 were included in the study (n = 333). Conditional logistic regression analyses were used to assess BCC risk by study factors.

RESULTS

A significantly increased risk was associated with smoking status in females but not in males. The risk was higher in dizygotic than in monozygotic females, possibly indicating the presence of a gene-smoking interaction. Suggestive but statistically nonsignificant increases in risk were observed for higher education, urticaria and atopic eczema, use of nonsteroidal anti-inflammatory drugs and coffee. A suggestive risk decrease was observed for outdoor work. No clear effects were observed for marital status, body mass index, use of alcohol, tea, fruit and vegetables or oral contraceptives.

CONCLUSIONS

The results suggest a role for smoking and possibly also for other lifestyle factors in the risk of contracting BCC.

Lifestyles, environmental and phenotypic factors associated with lip cancer: a case-control study in southern Spain

The aim of this study was to identify factors related to lip cancer (LC) considering individual characteristics and sociodemographic factors. A case-control study was carried out in the province of Granada (Andalusia, southern Spain). The cases were 105 males with squamous-cell carcinoma of the lip, diagnosed between 1987 and 1989 (aged 20-70 years) and identified by means of a population-based Cancer Registry. As controls, a randomised populational sample of 239 males, stratified by age, was used. Multiple logistic regression analysis showed that risk factors are lifetime cumulative tobacco consumption and alcohol consumption. An interaction was found between alcohol consumption and the smoking habit (leaving the cigarette on the lip): OR=23.6; 95% CI: 3.9-142.0. Other risk factors identified are clear eyes (OR=3.5; CI: 95% 1.5-8.0), sun exposure early in life and cumulative sun exposure during outdoor work (OR=11.9; 95%: CI: 1.3-108.9), and skin reaction to sun exposure (Fitzpatrick levels). Another interaction was found between skin reaction and a previous history of common sporadic warts (OR=4.4; 95% CI: 1.01-19.1). We conclude that LC is related to phenotype, skin reaction to sun exposure, cumulative and early sunlight exposure, and tobacco and alcohol consumption, as well as a low educational level. Leaving the cigarette on the lip is predictive of LC risk irrespective of cumulative tobacco consumption.

The influence of painful sunburns and lifetime sun exposure on the risk of actinic keratoses, seborrheic warts, melanocytic nevi, atypical nevi, and skin cancer

Painful sunburns are implicated in the pathogenesis of squamous cell carcinoma, basal cell carcinoma, and malignant melanoma. Chronic exposure to ultraviolet radiation is known as the most important risk factor for the development of actinic keratoses and squamous cell carcinoma. The purpose of the study was to assess the effect of painful sunburns and lifetime sun exposure on the development of actinic keratoses and seborrheic warts in relation to the development of squamous cell carcinoma and basal cell carcinoma, and on the development of melanocytic nevi and atypical nevi in relation to the development of malignant melanoma. We made use of a cohort of 966 individuals who participated in a case-control study to investigate environmental and genetic risk factors for skin cancer. Exposure measurements for sunlight were collected and actinic keratoses, seborrheic warts, melanocytic nevi, and atypical nevi were counted. Relative risks were estimated using exposure odds ratios from cross-tabulation. Multivariate logistic regression was used to adjust for potential confounders. The recall of painful sunburns before the age of 20 y was associated with an increased risk of squamous cell carcinoma, nodular basal cell carcinoma, and multifocal superficial basal cell carcinoma as well as actinic keratoses. Odds ratios with 95% confidence intervals adjusted for age, sex, and skin type were 1.5 (0.97; 2.3); 1.6 (1.1; 2.2); 2.6 (1.7; 3.8); and 1.9 (1.4; 2.6) for the three types of nonmelanoma skin cancer and actinic keratoses, respectively. Painful sunburns before the age of 20 y were also associated with an increased risk of malignant melanoma and the development of its precursors, melanocytic nevi and atypical nevi. Odds ratios with 95% confidence intervals adjusted for age, sex, and skin type were 1.4 (0.86; 2.1); 1.5 (1.1; 2.0); and 1.4 (0.88; 2.3) for malignant melanoma and the two types of precursors, respectively. Lifetime sun exposure was predominantly associated with an increased risk of squamous cell carcinoma (p-value for trend=0.03) and actinic keratoses (p-value for trend <0.0001) and to a lesser degree with the two types of basal cell carcinoma. By contrast, lifetime sun exposure appeared to be associated with a lower risk of malignant melanoma, despite the fact that lifetime sun exposure did not diminish the number of melanocytic nevi or atypical nevi. Neither painful sunburns nor lifetime sun exposure were associated with an increased risk of seborrheic warts.

Solar keratoses: analysis in a dermatological practice in Australia

Two hundred consecutive patients with solar keratoses (SK) seen in a private dermatology practice had on average 61.9 SK compared with eight reported in the general population. Non-melanoma skin cancer was present in 41% of patients and 17% had squamous cell carcinoma (SCC). The ratio of basal cell carcinoma to SCC in the cohort was 1.7:1. The commonest site of SK was the upper limbs but the greatest density of lesions was on the face, particularly the nose. Squamous cell carcinomas were most commonly found on the upper and lower limbs. Basal cell carcinomas were most common on the head and neck.

Susceptibility to Basal Cell Carcinoma is Associated with High Dermal Mast Cell Prevalence in Non–sun-exposed Skin for an Australian Population¶

In a Danish population, basal cell carcinoma (BCC) patients have a higher dermal mast cell prevalence in buttock skin than controls. This finding was supported by a functional link in mice between histamine-staining dermal mast cells and the extent of susceptibility to UV-B-induced systemic immunomodulation. It was important to confirm that this association was maintained in an Australian population with very different ancestry and sun exposure patterns. Australian BCC patients (n = 26) had significantly higher densities of mast cells in the dermis of buttock skin than control subjects (n = 25) (P = 0.0003, Mann-Whitney U-test). However, this correlation was lost at the sun-exposed site of the hand (P = 0.547, Mann-Whitney U-test). To further evaluate whether a relationship exists between dermal mast cell prevalence in sun-exposed skin and incidence of BCC in a larger study, biopsies of dorsal hand skin were obtained from an age-stratified random sample of 166 Queensland subjects, together with the 51 South Australian subjects, and dermal mast cell prevalence was quantified. Older subjects (over the median age of 42 years) had a greater incidence of BCC development (P = 0.0001, chi-square test) and significantly higher mast cell densities in hand skin (P = 0.0001, chi-square test) than younger subjects. However, mast cell density in sun-exposed hand skin was not significantly associated with BCC incidence. Finally, cellular expression of c-kit correlated with mast cell prevalence in non-sun-exposed skin, thereby implicating the stem cell factor-c-kit axis in the intrinsic mechanisms that regulate prevalence. These results show that high prevalence of dermal mast cells in buttock skin but not hand is associated with BCC development in an Australian population.

Environmental effects and skin disease

The skin is the largest organ in the body and one of its main functions is to protect the body from noxious substances, whether they are ultraviolet radiation, toxic chemicals or prolonged/repeated exposure to water. It is the level of exposure that determines if damage to the organism will result. The harm that can occur to the skin with sufficient exposure will be considered. Contact dermatitis, halogen acne, chemical depigmentation, connective tissue diseases and skin cancer are the conditions that will be covered in this chapter, as environmental exposure is important in their aetiologies. Systemic absorption will not be dealt with. Most environmental exposure to harmful substances will occur at work, but exposure may occur at home or during normal day-to-day activities.

Predictors of sun protection in Canadian adults

OBJECTIVE

An analysis of Canadian survey data was performed to identify independent predictors of different protective behaviours and of their use in combination.

METHODS

Data from light-skinned respondents of the 1996 National Survey on Sun Exposure & Protective Behaviours who spent 30+ minutes per day of their leisure time in the sun (N = 1,027) were analyzed. Multivariable logistic regression models were developed to identify independent predictors of four types of sun protection behaviour (avoiding the sun between 11 a.m. and 4 p.m., seeking shade, wearing protective clothing, applying sunscreen to the body) and of their use in combination.

RESULTS

Eighty-one percent of respondents reported performing at least one protective behaviour; each behaviour was practiced by between 40% and 48% of individuals. Respondents more likely to perform the behaviours in combination were older individuals, women and those who did not report being unconcerned about sun protection, wanting a tan, finding sun protection inconvenient or being forgetful about protecting oneself from the sun. These characteristics were generally found to predict each of the individual behaviours, with some notable exceptions (women were less likely than men to wear protective clothing; older individuals were less likely to report sunscreen use). Individuals with a higher education level were more likely to report wearing protective clothing and applying sunscreen. Similarly, respondents reporting a higher income level reported sunscreen use more often.

INTERPRETATION

These findings suggest predictors of sun protection to be considered for the targeting of sun safety initiatives to Canadians with poor sun protection practices.

New treatment modalities for basal cell carcinoma

Basal cell carcinoma (BCC) is a subtype of nonmelanoma skin cancer (NMSC), a potentially fatal disease linked to overexposure to the sun during childhood. BCC has been associated with UV-induced mutations of the PTC and p53 tumor suppressor genes, and to polymorphisms in the melanocortin-1 receptor and XPD genes. Mortality rates due to BCC are low, but its increasing incidence and prolonged morbidity means the disease is costly to treat. Early recognition and effective treatment are therefore important, to reduce the incidence of BCC and lighten the economic burden of its management. This paper reviews current treatments for BCC, including excision and curettage, electrodessication, surgery, cryosurgery, radiotherapy, and treatment with 5-fluorouracil and intralesional/perilesional cytokines. It also deals with two new treatment modalities, photodynamic therapy and imiquimod 5% cream, an immune response modifier that effectively resolves BCC lesions.

Skin cancer and ultraviolet-B radiation under the Antarctic ozone hole: southern Chile, 1987-2000

BACKGROUND

Punta Arenas, Chile, the southernmost city in the world (53 degrees S), with a population of 154,000, is located near the Antarctic ozone hole (AOH) and has been regularly affected by high levels of ultraviolet-B (UV-B) radiation each spring for the last 20 years. Large increases in UV-B associated with the AOH have been measured with increases in UV-B at 297 nm of up to 38 times those of similar days with normal ozone. Recently we reported significant increases in sunburns during the spring of 1999 on days with low ozone because of the AOH.

METHODS

A surveillance of skin cancers occurring from 1987 to 2000 was performed. Age, sex, location, type of skin cancer and skin phototype were recorded. A Brewer Spectrophotometer was used in order to obtain in situ measurements of ozone and UV-B. Total Ozone Mapping Spectrometer (TOMS) data from National Aeronautics and Space Administration (NASA) was used in order to establish pre-ozone hole climatology.

RESULTS

Ozone levels as low as 145 DU (Dobson Units) were recorded, a 56% decrease in ozone, and UV-B levels up to 4.947 J/m2. These levels are close to summertime levels at mid latitudes. For the 14-year period--from 1987 to 2000--173 cases of skin cancer were diagnosed, 65 during the first 7 years, 108 during the second, an increase of 66%. Cutaneous malignant melanoma (CMM), 19% of the cases, increased by 56%, raising the rate from 1.22 to 1.91 per 100,000. Non-melanoma skin cancer (NMSC), 81% of the total, increased the rate from 5.43 to 7.94 per 100 000 (P < 0.05), a 46% increase. Patients with CMM and NMSC had skin phototypes I-II in 59% and 54% of cases, respectively. Days with more than 25% ozone loss occurred in 143 days during the last 20 springs. Significant increases of UV-B were observed under ozone hole conditions, especially around 300 nm, the most carcinogenic wavelengths.

CONCLUSIONS

Highly unusual ozone loss and UV-B increases have occurred in the Punta Arenas area over the past two decades resulting in the non-photoadapted population being repeatedly exposed to an altered solar UV spectrum with a greater effectiveness for erythema and photocarcinogenesis. This phenomenon has not previously been reported over other populated areas and an additional increase in the skin cancer rate attributable to the AOH may be occurring. Research on the clinical and subclinical impact of these abnormalities is urgently needed.

Environment, phenotype and genetics: risk factors associated with BCC of the skin

Basal cell carcinoma is the most common cancer in Caucasians and its incidence is rising. Whilst not life threatening, the tumor can cause substantial morbidity and because of long follow-up, it places a major burden on healthcare agencies worldwide. Patients with the disease demonstrate wide phenotypic diversity with respect to tumor numbers, rate of tumor appearance and site. The factors involved in patient susceptibility to basal cell carcinoma are not well understood although exposure to ultraviolet radiation in sunlight appears critical. In this review we discuss the role of environmental and genetic factors on predisposition to basal cell carcinoma and illustrate how stratification of the basal cell carcinoma cohort into high-risk subgroups is helpful in identifying factors significant in disease susceptibility.

Increased dermal mast cell prevalence and susceptibility to development of basal cell carcinoma in humans

Exposure to ultraviolet B (UVB) radiation (280-320 nm) is the primary etiologic factor associated with the development of basal cell carcinoma (BCC). The outgrowth of these keratinocyte-derived skin lesions is enhanced by the ability of UVB to impair an immune response that would otherwise eliminate them. Studies in a range of inbred mouse strains as well as mast cell-depleted mice reconstituted with mast cell precursors support a functional link between histamine-staining dermal mast cells and the extent of susceptibility to UVB-induced systemic immunomodulation. Humans, like mouse strains, display variations in dermal mast cell prevalence. In a study of Danish and South Australian BCC patients and control subjects, one 4-mm punch biopsy of non-sun-exposed buttock skin was sampled from each participant. This skin site was investigated to avoid any changes in mast cell prevalence caused by sun exposure. Two sections (4 microm) per biopsy were immunohistochemically stained for detection of histamine-containing dermal mast cells. Computer-generated image analysis evaluated dermal mast cell prevalence in both sections by quantifying the total number of mast cells according to the total dermal area (expressed as mast cells per square millimeter). This technique enabled us to detect heterogeneity of dermal mast cell prevalence in buttock skin between individuals and provided evidence of an association between high dermal mast cell prevalence and BCC development in two diverse populations. We hypothesize that mast cells function in humans, as in mouse strains, by initiating immunosuppression following UV irradiation and, thereby, allowing a permissive environment for the development of BCC. Thus, a high dermal mast cell prevalence as demonstrable in buttock skin is a significant predisposing factor for development of BCC in humans.

Sun-related behaviors of outdoor working men with a history of non-melanoma skin cancer

The present study describes sun exposure and sun protection behaviors of northern Australian outdoor workers with previous non-melanoma skin cancer (NMSC). In 1999 a cross-sectional study of northern Australian men with previous NMSC was conducted by self-administered questionnaire. Compared to other men, outdoor workers spent more time in the sun on average working days and days off (P < 0.0001, respectively), and outdoor workers with sun-sensitive skin reported that more skin lesions had been removed (P = 0.0461). The workplace did not reinforce sun-safe practices of 36.8% of workers who spent half their time or more outdoors. Sun-protective behaviors were not different between in- and outdoor workers. Outdoor workers experienced high levels of sun exposure, however, sun-protective behavior was similar to other workers. Workplaces should be targeted to reinforce sun-safe policies.

Sunburn prevalence among adults in the United States, 1999

BACKGROUND

Exposure to high levels of sunlight, such as a sunburn, is a strong determinant of melanoma risk.

METHODS

To describe statewide and U.S. estimates of sunburn prevalence in the United States and determine demographic and behavioral predictors of sunburn, we analyzed data from the 1999 Behavioral Risk Factor Surveillance System, a population-based telephone survey conducted in all 50 states, the District of Columbia, and Puerto Rico.

RESULTS

Of 156,354 adults aged > or =18 years, 31.7% (95% confidence interval, 31.3%-32.1%) reported a sunburn in the past year; of adults aged 18 to 29 years, 57.5% reported such a sunburn. Reporting was highest among white, non-Hispanic males (44.1%), followed by white non-Hispanic females (35.3%), and lowest among black non-Hispanic males and females (5.1% and 5.3%, respectively). Statewide period prevalence of sunburn among whites was highest (>45%) in Wisconsin, Utah, Wyoming, Washington, DC, and Indiana, and lowest (<30%) in Puerto Rico, Arizona, Tennessee, Oklahoma, and New York.

CONCLUSIONS

Nationwide and statewide skin cancer prevention efforts should target young adults. Periodic monitoring of sunburn is important in evaluating the effectiveness of those efforts.

Sun exposure and sun protection in young European children: an EORTC multicentric study

Most European children experience exposure to the sun during the summer holidays. The aim of this study was to examine the behaviour of European children when in the sun during their holidays. In 1995-1997, a total of 631 young children were recruited during a multicentric study in Belgium, Germany, France and Italy. For each holiday period from birth, parents gave detailed information on sun exposure and child behaviour. Predictors and trends over time of sun protection were investigated. Forty percent of children were exposed to sunlight in the first and 86% in the sixth year of life. At the same time, the number of children who experienced sunburns rose from 1 to 23%. In the whole period of 6 years, only 8% of children always wore trousers and shirt when in the sun, while 25% children always used a sunscreen. The proportion of sun-exposed children who used sunscreen was stable with age (approximately 50%), while those who always wore trousers and shirts dropped from 46% (1st year) to 19% (6th year). Multinomial logistic regression showed that sunscreen use, but not the wearing of clothes was associated with sun-sensitivity. In summary, sun exposure increases steadily, while sun protection decreases in the first 6 years of life in our cohort of children. In this cohort, use of a sunscreen was much more frequent than the wearing of clothes and a reduction in sun exposure.

Skin cancer after X-ray treatment for scalp ringworm

Some 2,224 children given X-ray therapy for tinea capitis (ringworm of the scalp) have been followed for up to 50 years to determine cancer incidence, along with a control group of 1,380 tinea capitis patients given only topical medications. The study found a relative risk (RR) of 3.6 (95% confidence interval, 2.3-5.9) for basal cell skin cancer (BCC) of the head and neck among irradiated Caucasians (124 irradiated cases and 21 control cases), in response to a scalp dose of about 4.8 Gy. No melanomas of the head and neck have been seen, and only a few squamous cell carcinomas. About 40% of irradiated cases have had multiple BCCs, for a total of 328 BCCs. Although 25% of both the irradiated and control groups are African-American, only 3 skin cancers have been seen among them, all in the irradiated group, indicating the importance of susceptibility to UV radiation as a cofactor. Light complexion, severe sunburning and North European ancestry were predictive of BCC risk in the irradiated group, but chronic sun exposure was not. Children irradiated at young ages had the highest BCC risk. The RR for BCC risk is approximately constant with time since exposure, suggesting that risk will probably last for a lifetime.

Development of an integrated method of skin phenotype measurement using the melanins

Different types of melanin pigments have recently been identified and recognized as critical determinants of the photosensitivity of individuals. Eumelanin, the black to brown melanin pigments, are believed to protect against ultraviolet-induced cell damage, while phaeomelanin, the reddish brown variant, is thought to be photosensitizing. The relative, qualitative and absolute amount of melanin production under stimulation of solar radiation is likely to be genetically determined. The hypothesis of this study is that determination of these values can help in identifying those people who are less protected. However, these techniques must be evaluated at a population level and against traditional epidemiological measures. We assessed the amount and type of melanin in 195 subjects in four centres across Europe, relating the results to epidemiological measures such as skin characteristics, history of sunburns and number of naevi. The most important finding was that eumelanin and phaeomelanin have very different distributions in the population, being associated with other phenotype characteristics with different patterns. The relationship between phaeomelanin and eumelanin is linearly inverse in the range from black to dark blonde hair colour, while it is weakly directly proportional in the range from dark blonde to light blonde, with people with red hair showing a peculiar pattern. Phaeomelanin rather than eumelanin seemed to be independent of other skin characteristics. The results show the feasibility of a further study with an appropriate case-control design and accurate determination of melanin.

UV doses of American children and adolescents

The ultraviolet (UV) doses of American young adults were never measured, but are needed for assessing UV-related health risks. These doses were calculated using a novel approach. The National Human Activity Pattern Survey recorded the daily minute-by-minute activities of about 2000 young adults (0-19 years) over the course of 2 years to assess their exposure to environmental pollutants. From that survey, only the outdoor daylight data of northern and southern girls and boys were extracted and stratified by season and age to find the time American children (0-5 and 6-12 years) and adolescents (13-19 years) spend outside. They spend about 10% of the day outdoors, but only get about 30% of the available terrestrial UV radiation (on a horizontal plane). American children have about the same percent personal ambients as adults (3.1%), 2.8% for girls and 3.4% for boys. Adolescents have the lowest personal ambients (2.6%), 2.1% for girls and 3.1% for boys. To get their UV doses, their percent ambients are multiplied by the total available terrestrial UV. Excluding vacation, the erythemally weighted UV doses for American children are 25 kJ/m2/year, 23 for girls and 28 for boys. Adolescents get the lowest UV exposure of any group, 21 kJ/m2/year, 18 for girls and 24 for boys. Young adult northern girls get 18 kJ/m2/year and boys get 21 kJ/m2/year, whereas southern girls get 24 kJ/m2/year and boys get 31 kJ/m2/year. The youngest children (0-5 years) get slightly higher summer doses. Thus, we can now assess the UV-related health risks for American children and adolescents.

Predictors of sunburn among Canadian adults

BACKGROUND

Data from the 1996 National Survey on Sun Exposure & Protective Behaviors (4,023 respondents) were analyzed to identify independent predictors of sunburn among adult Canadians.

METHODS

Multivariate models predicting sunburn odds were developed using unconditional logistic regression. Backward elimination model selection was used to identify independent predictors of sunburn.

RESULTS

Nonbehavioral characteristics found to predict sunburn were younger age, male sex, light skin color, nonblack hair color, and birthplace in North America or Europe. Behavioral predictors of sunburn included high awareness of the UV Index, working outdoors in the summer, longer leisure time in the sun, forgetfulness about protecting oneself from the sun, and seeking a tan. Sun avoidance between 11 AM and 4 PM was associated with lower odds of sunburn, while seeking shade when outside and use of protective clothing showed nonsignificant associations with lower sunburn odds. Sunscreen use was found to have a nonsignificant positive association with sunburn.

CONCLUSIONS

These findings highlight risk factors to be considered in the targeting of sunburn reduction strategies to high-risk groups and suggest that sun avoidance, seeking shade, and use of protective clothing may be effective in preventing sunburn.