The effects of exposure to solar radiation on human health

This assessment by the Environmental Effects Assessment Panel (EEAP) of the Montreal Protocol under the United Nations Environment Programme (UNEP) evaluates the effects of ultraviolet (UV) radiation on human health within the context of the Montreal Protocol and its Amendments. We assess work published since our last comprehensive assessment in 2018. Over the last four years gains have been made in knowledge of the links between sun exposure and health outcomes, mechanisms, and estimates of disease burden, including economic impacts. Of particular note, there is new information about the way in which exposure to UV radiation modulates the immune system, causing both harms and benefits for health. The burden of skin cancer remains high, with many lives lost to melanoma and many more people treated for keratinocyte cancer, but it has been estimated that the Montreal Protocol will prevent 11 million cases of melanoma and 432 million cases of keratinocyte cancer that would otherwise have occurred in the United States in people born between 1890 and 2100. While the incidence of skin cancer continues to rise, rates have stabilised in younger populations in some countries. Mortality has also plateaued, partly due to the use of systemic therapies for advanced disease. However, these therapies are very expensive, contributing to the extremely high economic burden of skin cancer, and emphasising the importance and comparative cost-effectiveness of prevention. Photodermatoses, inflammatory skin conditions induced by exposure to UV radiation, can have a marked detrimental impact on the quality of life of sufferers. More information is emerging about their potential link with commonly used drugs, particularly anti-hypertensives. The eyes are also harmed by over-exposure to UV radiation. The incidence of cataract and pterygium is continuing to rise, and there is now evidence of a link between intraocular melanoma and sun exposure. It has been estimated that the Montreal Protocol will prevent 63 million cases of cataract that would otherwise have occurred in the United States in people born between 1890 and 2100. Despite the clearly established harms, exposure to UV radiation also has benefits for human health. While the best recognised benefit is production of vitamin D, beneficial effects mediated by factors other than vitamin D are emerging. For both sun exposure and vitamin D, there is increasingly convincing evidence of a positive role in diseases related to immune function, including both autoimmune diseases and infection. With its influence on the intensity of UV radiation and global warming, the Montreal Protocol has, and will have, both direct and indirect effects on human health, potentially changing the balance of the risks and benefits of spending time outdoors.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021

The Environmental Effects Assessment Panel of the Montreal Protocol under the United Nations Environment Programme evaluates effects on the environment and human health that arise from changes in the stratospheric ozone layer and concomitant variations in ultraviolet (UV) radiation at the Earth’s surface. The current update is based on scientific advances that have accumulated since our last assessment (Photochem and Photobiol Sci 20(1):1–67, 2021). We also discuss how climate change affects stratospheric ozone depletion and ultraviolet radiation, and how stratospheric ozone depletion affects climate change. The resulting interlinking effects of stratospheric ozone depletion, UV radiation, and climate change are assessed in terms of air quality, carbon sinks, ecosystems, human health, and natural and synthetic materials. We further highlight potential impacts on the biosphere from extreme climate events that are occurring with increasing frequency as a consequence of climate change. These and other interactive effects are examined with respect to the benefits that the Montreal Protocol and its Amendments are providing to life on Earth by controlling the production of various substances that contribute to both stratospheric ozone depletion and climate change.

A risk prediction model for the development of subsequent primary melanoma in a population-based cohort

BACKGROUND

Guidelines for follow-up of patients with melanoma are based on limited evidence.

OBJECTIVES

To guide skin surveillance, we developed a risk prediction model for subsequent primary melanomas, using demographic, phenotypical, histopathological, sun exposure and genomic risk factors.

METHODS

Using Cox regression frailty models, we analysed data for 2613 primary melanomas from 1266 patients recruited to the population-based Genes, Environment and Melanoma study in New South Wales, Australia, with a median of 14 years' follow-up via the cancer registry. Discrimination and calibration were assessed.

RESULTS

The median time to diagnosis of a subsequent primary melanoma decreased with each new primary melanoma. The final model included 12 risk factors. Harrell's C-statistic was 0·73 [95% confidence interval (CI) 0·68-0·77], 0·65 (95% CI 0·62-0·68) and 0·65 (95% CI 0·61-0·69) for predicting second, third and fourth primary melanomas, respectively. The risk of a subsequent primary melanoma was 4·75 times higher (95% CI 3·87-5·82) for the highest vs. the lowest quintile of the risk score. The mean absolute risk of a subsequent primary melanoma within 5 years was 8·0 ± SD 4.1% after the first primary melanoma, and 46·8 ± 15·0% after the second, but varied substantially by risk score.

CONCLUSIONS

The risk of developing a subsequent primary melanoma varies considerably between individuals and is particularly high for those with two or more primary melanomas. The risk prediction model and its associated nomograms enable estimation of the absolute risk of subsequent primary melanoma, on the basis of on an individual's risk factors, and can be used to tailor surveillance intensity, communicate risk and provide patient education. What's already known about this topic? Current guidelines for the frequency and length of follow-up to detect new primary melanomas in patients with one or more previous primary melanomas are based on limited evidence. People with one or more primary melanomas have, on average, a higher risk of developing another primary invasive melanoma, compared with the general population, but an accurate way of estimating individual risk is needed. What does this study add? We provide a comprehensive risk prediction model for subsequent primary melanomas, using data from 1266 participants with melanoma (2613 primary melanomas), over a median 14 years' follow-up. The model includes 12 risk factors comprising demographic, phenotypical, histopathological and genomic factors, and sun exposure. It enables estimation of the absolute risk of subsequent primary melanomas, and can be used to tailor surveillance intensity, communicate individual risk and provide patient education.

Genetic factors associated with naevus count and dermoscopic patterns: preliminary results from the Study of Nevi in Children (SONIC)

BACKGROUND

Melanocytic naevi are an important risk factor for melanoma. Naevi with distinct dermoscopic patterns can differ in size, distribution and host pigmentation characteristics.

OBJECTIVES

We examined MC1R and 85 other candidate loci in a cohort of children to test the hypothesis that the development and dermoscopic type of naevi are modulated by genetic variants.

METHODS

Buccal DNAs were obtained from a cohort of 353 fifth graders (mean age 10·4 years). Polymorphisms were chosen based on a known or anticipated role in naevi and melanoma. Associations between single-nucleotide polymorphisms (SNPs) and baseline naevus count were determined by multivariate regression adjusting for sex, race/ethnicity and sun sensitivity. Dermoscopic images were available for 853 naevi from 290 children. Associations between SNPs and dermoscopic patterns were determined by polytomous regression.

RESULTS

Four SNPs were significantly associated with increasing (IRF4) or decreasing (PARP1, CDK6 and PLA2G6) naevus count in multivariate shrinkage analyses with all SNPs included in the model; IRF4 rs12203952 showed the strongest association with log naevus count (relative risk 1·56, P < 0·001). Using homogeneous naevi as the reference, IRF4 rs12203952 and four other SNPs in TERT, CDKN1B, MTAP and PARP1 were associated with either globular or reticular dermoscopic patterns (P < 0·05).

CONCLUSIONS

Our results provide evidence that subsets of naevi defined by dermoscopic patterns differ in their associations with germline genotypes and support the hypothesis that dermoscopically defined subsets of naevi are biologically distinct. These results require confirmation in larger cohorts. If confirmed, these findings will improve the current knowledge of naevogenesis and assist in the identification of individuals with high-risk phenotypes.

Prediabetes: The Variation between HbA1c and Fasting Plasma Glucose

PURPOSE

The prevalence of Diabetes Type 2 is on the rise internationally. Currently, Fasting Plasma Glucose (FPG) and HbA1c are both used to determine if an individual is diabetic or prediabetic. We aimed to describe the prevalence of diabetes, prediabetes, and glycemic control in a population-based sample of elderly Hispanic and non-Hispanic White participants in New Mexico.

METHODS

To do this, we compared HbA1c with FPG using Chi-Square analysis across gender and ethnicity to provide information for future health care policy. We also performed non-parametric regression using a locally weighted smoothing technique to investigate the relationship between FPG and HbA1c levels.

RESULTS

Our analysis identifies a large variation between the sensitivity of HbA1c and FPG in the identification of both prediabetes and diabetes. Interestingly, 95% of diabetics defined by FPG are also defined by HbA1c, representing overlap between the two measures. When comparing the prevalence of prediabetes between the two measures, the overlap of FPG with HbA1c was only 30% and HbA1c identifies more individuals as prediabetic than FPG. Prevalence of diabetes was also higher when defined by HbA1c compared to FPG and the overall agreement between HbA1c and FPG appears to be poor particularly by sex and ethnicity (K=0.22-0.34). Glycemic control was poor overall with Hispanics displaying a larger amount of uncontrolled diabetes.

CONCLUSION

We compared HbA1c and FPG by gender and ethnicity and showed both measures of diabetes differ in their sensitivity across ethnic groups. Our results suggest that using HbA1c, rather than FPG, results in higher rates of prediabetes and diabetes, a finding with numerous implications for health care practice.

The good, the bad, and the ugly of sunscreens

Sunscreens protect against sunburn, but there is no evidence that they protect against basal cell carcinoma or melanoma. Problems lie in the behavior of individuals who use sunscreens to stay out longer in the sun than they otherwise would. Vitamin D inhibition is, at this stage, unlikely due to insufficient use by individuals. Safety of sunscreens is a concern, and sunscreen companies have emotionally and inaccurately promoted the use of sunscreens.

Sociodemographic factors influencing Breslow thickness at diagnosis for patients with melanoma

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Background: In previous work, we demonstrated that Breslow thickness at diagnosis is significantly related to distance to provider for patients with melanoma in North Carolina (NC). Expanding the study population to include patients in New Jersey (NJ) and southern California (CA), we hypothesize that distance to provider is an effective measure of access to melanoma care regardless of geographic region. Methods: An IRB-approved secondary data analysis was performed of all incident cases of invasive cutaneous melanoma in 2000 from 3 population-based ascertainment areas (CA, NC, NJ). Patients and providers were geocoded to street address; Euclidian distances between patients and providers were calculated. The outcome variable, Breslow thickness at diagnosis, was logged for analysis. Simple and multiple linear regression were used to test associations between Breslow thickness and multiple sociodemographic factors. Results: Of 1,408 eligible cases, 16% were excluded for missing Breslow data. Median Breslow thickness was 0.6 mm (range 0.01–30.0 mm). Median distance to provider was 7 miles (range 0–372 miles). There was no significant difference in Breslow between the 3 geographic regions. Males had on average 15.5% thicker tumors than females, p=0.009. Patients 51–80 years old had 15.3% thicker tumors than patients =50, p=0.015, and those >80 had 64.3% thicker tumors than patients =50, p<0.001. For all patients, Breslow thickness increased only 2% for each 10 mile increase in distance, p=0.047. However, when limited to patients from rural areas, each 10 mile increase in distance corresponded to an 8% increase in Breslow, p<0.001. Meanwhile, Breslow was not associated with any area-based measures of rurality or provider supply. Each 1% increase in poverty rate corresponded to a 1% increase in Breslow, p=0.036. Conclusion: Breslow thickness at diagnosis is strongly correlated with distance to provider, especially for patients from rural areas. Distance to provider is a better measure of access to melanoma care than area-based measures of rurality.

No significant financial relationships to disclose.

A note on competing risks in survival data analysis

Survival analysis encompasses investigation of time to event data. In most clinical studies, estimating the cumulative incidence function (or the probability of experiencing an event by a given time) is of primary interest. When the data consist of patients who experience an event and censored individuals, a nonparametric estimate of the cumulative incidence can be obtained using the Kaplan-Meier method. Under this approach, the censoring mechanism is assumed to be noninformative. In other words, the survival time of an individual (or the time at which a subject experiences an event) is assumed to be independent of a mechanism that would cause the patient to be censored. Often times, a patient may experience an event other than the one of interest which alters the probability of experiencing the event of interest. Such events are known as competing risk events. In this setting, it would often be of interest to calculate the cumulative incidence of a specific event of interest. Any subject who does not experience the event of interest can be treated as censored. However, a patient experiencing a competing risk event is censored in an informative manner. Hence, the Kaplan-Meier estimation procedure may not be directly applicable. The cumulative incidence function for an event of interest must be calculated by appropriately accounting for the presence of competing risk events. In this paper, we illustrate nonparametric estimation of the cumulative incidence function for an event of interest in the presence of competing risk events using two published data sets. We compare the resulting estimates with those obtained using the Kaplan-Meier approach to demonstrate the importance of appropriately estimating the cumulative incidence of an event of interest in the presence of competing risk events.

Estimating the relative risk of developing melanoma in INK4A carriers

Estimation of the relative risk of cancer due to rare germline mutations using population-based epidemiological techniques is challenging, since studies with very large numbers of subjects are required. In this pilot study using a novel study design, we evaluated the role of INK4A mutations in melanoma by comparing patients with multiple primary melanomas to those with single primaries. Patients were ascertained from the Surgery and Dermatology Clinics at Memorial Sloan-Kettering Cancer Center and at the Yale University Pigmented Lesion Clinic. Subjects completed a questionnaire covering risk factors for melanoma and were tested for INK4A mutations. Five (8%) of 65 patients with multiple primaries had a mutation, compared with none of 88 patients with single primaries (P=0.03). Examination of other factors, such as number of nevi on the arms of the patients, fair skin, hair and eye colour, and other phenotypic characteristics associated with the risk of melanoma, demonstrates that these factors exhibit higher prevalence in the multiple primary cases than in the single primaries. These results provide evidence of the utility of the new study design in evaluating the impact of rare but highly penetrant cancer risk factors.

Randomized, placebo-controlled trial of dietary supplementation of alpha-tocopherol on mutagen sensitivity levels in melanoma patients: a pilot trial

We evaluated the effects of vitamin E (dl-alpha-tocopherol) on mutagen sensitivity levels in a randomized placebo-controlled pilot trial. In brief, a dietary supplement of 1000 mg/day vitamin E or a placebo was randomly administered for 3 months to melanoma outpatients clinically free of the disease. Plasma vitamin E and mutagen sensitivity levels were measured at baseline and at the end of the trial after 3 months. At baseline, we found no significant differences in plasma vitamin E and mutagen sensitivity levels between the two groups. We also measured dietary intake at baseline and found dietary vitamin E to be a poor predictor of plasma levels of vitamin E. After 3 months of supplementation, we found that plasma levels of alpha-tocopherol increased significantly (P = 0.0005) in the vitamin E compared to the placebo group. We also found a non-significant, but consistent decrease in plasma gamma-tocopherol concentrations in the vitamin E supplemented compared to the placebo group. We did not find any significant difference between the vitamin E and placebo groups in mutagen sensitivity levels either at baseline or after 3 months of supplementation. We conclude that short term vitamin E supplementation, although it causes increased blood levels of alpha-tocopherol, does not provide protection against bleomycin-induced chromosome damage.

Validation of denaturing high performance liquid chromatography as a rapid detection method for the identification of human INK4A gene mutations

The incidence of melanoma is increasing rapidly in western countries. Genetic predisposition in familial and in some sporadic melanomas has been associated with the presence of INK4A gene mutations. To better define the risk for developing sporadic melanoma based on genetic and environmental interactions, large groups of cases need to be studied. Mutational analysis of genes lacking hot spots for sequence variations is time consuming and expensive. In this study we present the application of denaturing high performance liquid chromatography (DHPLC) for screening of mutations. Exons 1alpha, 2, and 3 were amplified from 129 samples and 13 known mutants, yielding 347 products that were examined at different temperatures. Forty-two of these amplicons showed a distinct non-wild-type profile on the chromatogram. Independent sequencing analysis confirmed 16 different nucleotide variations in Leu32Pro; Ile49Thr; 88 del G; Gln50Arg; Arg24Pro; Met53Ile; Met53Thr; Arg58stop; Pro81Leu; Asp84Ala; Arg80stop; Gly101Trp; Val106Val; Ala148Thr; and in positions (-2) in intron 1 (C --> T); and in the 3' UTR, nucleotide 500 (C --> G). No false negatives or false positives were obtained by DHPLC in samples with mutations or polymorphisms. We conclude that the DHPLC is a fast, sensitive, cost-efficient, and reliable method for the scanning of INK4A somatic or germline mutations and polymorphisms of large number of samples.

Double-strand breaks and tumorigenesis

The establishment of connections between biochemical defects and clinical disease is a major goal of modern molecular genetics. In this review, we examine the current literature that relates defects in the two major DNA double-strand-break repair pathways--homologous recombination and nonhomologous end-joining--with the development of human tumors. Although definitive proof has yet to be obtained, the current literature is highly suggestive of such a link.

Issues in the epidemiology of melanoma

Cutaneous melanoma is a significant health problem throughout the developing world. Primary and secondary prevention are discussed. The wavelengths of the ultraviolet radiation spectrum and their association with melanoma are discussed. Although excessive sun exposure during childhood is a critical risk factor, excessive sun exposure during adult years is also important. The major risk factors for melanoma--numerous or atypical moles and a sun-sensitive phenotype--are genetic. Their interaction with sun exposure is currently being examined, as well as the interaction of other genetic factors, such as alterations in the melanocortin receptor and the familial melanoma gene, INK4A. Secondary prevention strategies include self-examination and physician examination. New technologies are being developed to supplement visual examination of suspected lesions. These technologies are discussed in detail and include digital photography, digital dermoscopy, confocal scanning laser microscopy and automated diagnosis systems.

Histologic classification of tumor-infiltrating lymphocytes in primary cutaneous malignant melanoma. A study of interobserver agreement

The density and distribution of lymphocytes infiltrating the vertical growth phase of primary cutaneous melanomas has been suggested by several studies to be of prognostic significance. However, few pathologists comment on tumor-infiltrating lymphocytes (TILs), and there is the perception that the assessment of TILs is subject to great interobserver variability. We studied interobserver agreement on the categorization of TILs; 20 cases of primary cutaneous malignant melanoma with a vertical growth phase component were circulated among 3 pathologists and 3 dermatologists. For each case, TILs were classified as brisk, nonbrisk, or absent according to Clark. Only 1 pathologist (a dermatopathologist) was familiar with the classification of TILs. Observers were given written guidelines and a brief tutorial before their examination of the slides. Our results show that with little instruction, overall agreement among observers was good (kappa values, 0.6 or more), especially among pathologists (kappa values, > 0.7). Three observers had excellent agreement among each other (kappa values, > 0.75). These findings suggest that the categorization of TILs can be easily taught and can be applied with an acceptable level of reproducibility in routine diagnostic practice.

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.

Mutagen sensitivity as an indicator of soft tissue sarcoma risk

The etiology of soft tissue sarcoma is poorly understood. Exposure to environmental chemicals may play a role, but the data are not clear. We compared a group of soft tissue sarcoma patients with healthy controls to determine whether the mutagen sensitivity assay, a simple chromosome aberration assay using the radiomimetic bleomycin, might be useful to identify patients at risk for soft tissue sarcoma. Patients with a diagnosis of soft tissue sarcoma at Memorial Sloan-Kettering's outpatient clinic signed informed consent and donated 30 ml of blood. Controls were selected from the general population of Connecticut by random digit dialing. Unrepaired DNA damage was assessed for 100 metaphase spreads for each individual, with the number of breaks in chromatids being counted as breaks per cell (b/c). The 20 cases with soft tissue sarcoma had 1.03 mean b/c and the controls had 0.88 b/c (P = 0.16). Patients with soft tissue sarcoma were 5.7 times more likely to be mutagen sensitive than controls (P = 0.01), as determined after dividing subjects into sensitive or not sensitive groups based on the median b/c among controls. As mutagen sensitivity has been shown to be associated with a number of cancers and appears to reflect genetic susceptibility, this assay may be an appropriate biomarker for radiation sensitivity or it may be a marker of susceptibility to soft tissue sarcoma. Larger studies should be undertaken to assess these possibilities.

Signs and symptoms of melanoma in older populations

We conducted a descriptive study to assess the relationship between increasing age and the reporting of melanoma signs/symptoms in 634 hospital-based and 624 population-based incident cases of melanoma. Multivariate logistic regression was used to evaluate the relationship between older age (> or = 50 years) and the reporting of melanoma signs/symptoms. Older patients were less likely to report itching and change in elevation of their lesions (P < 0.05). Change in color was also less likely to be reported by older patients, although not statistically significant. Ulceration of the lesion was reported significantly more by older patients (P < 0.05). Older individuals may be less likely to report itching and change in elevation/color of their lesions, but more likely to report ulceration, a symptom associated with advanced disease and poor prognosis. Further research is necessary to provide a better understanding of the development of melanoma in older populations so that new strategies can be explored to improve early detection in this age group.

Patterns of detection in patients with cutaneous melanoma

BACKGROUND

Despite the importance of early detection in preventing mortality from melanoma, little is known regarding how patients with the disease come to diagnosis.

METHODS

The authors prospectively evaluated 471 newly diagnosed melanoma patients between 1995 and 1998. Patients completed a questionnaire that included 1) identification of the person who detected the lesion, 2) the anatomic location of the lesion, and 3) family history of melanoma. Logistic regression analysis was performed to examine the relation between detection patterns and lesion thickness, adjusting for age, gender, anatomic site of the primary lesion, and family history of melanoma.

RESULTS

The majority of patients detected their own melanoma (n = 270; 57%). Females were more likely to self-detect than males (69% vs. 47%; P < 0.0001). Physicians detected the melanoma in 16% of patients (n = 74), followed by "spouse" in 11% of patients (n = 51). Within this group, detection by wives was 7.5 times more common than detection by husbands (P < 0.0001). Logistic regression analysis revealed that physicians were 3.6 times more likely to detect thin lesions (</=0.75 mm) compared with nonphysician detectors (95% confidence interval [95% CI], 2.1, 6.5; P = 0.0001). In addition, patients who reported a family history of melanoma had a 2.7-fold increased likelihood of presenting with a thin lesion (95% CI, 1.6, 4.7; P = 0.0003).

CONCLUSIONS

Physician detection and a report of a family history of melanoma are associated with the presentation of patients with early melanoma, suggesting that awareness of the disease among physicians and the public is critical for preventing mortality from melanoma. Increasing melanoma awareness in males may be a particularly effective means of secondary prevention.

Gene-environment interaction in melanoma

Gene-environment interaction can be defined as a different effect of an environmental exposure in people with different genotypes, or a different effect of a genotype in people with different histories of environmental exposure. Interaction applies when one stratum (high risk) responds differently to an exposure (sun) than another stratum (low risk). Genetic predisposition would appear to be a very important modifier of risk. This paper discusses the concept of gene-environment interaction applied to cutaneous melanoma through discussion of highly penetrant genes and their interaction with sun exposure, through discussion of low penetrant genes and their interaction with sun exposure, and by suggesting a new model for investigation of gene-environment interaction in melanoma. It is stressed that this area of investigation is extremely early in its development.

Markers of DNA repair and susceptibility to cancer in humans: an epidemiologic review

DNA repair is a system of defenses designed to protect the integrity of the genome. Deficiencies in this system likely lead to the development of cancer. The epidemiology of DNA repair capacity and of its effect on cancer susceptibility in humans is, therefore, an important area of investigation. We have summarized all of the published epidemiologic studies on DNA repair in human cancer through 1998 (n = 64) that addressed the association of cancer susceptibility with a putative defect in DNA repair capacity. We have considered study design, subject characteristics, potential biases, confounding variables, and sources of technical variability. Assays of DNA repair capacity used, to date, can be broadly grouped into five categories: 1) tests based on DNA damage induced with chemicals or physical agents, such as the mutagen sensitivity assay, the G(2)-radiation assay, induced micronuclei, and the Comet assay; 2) indirect tests of DNA repair, such as unscheduled DNA synthesis; 3) tests based on more direct measures of repair kinetics, such as the host cell reactivation assay; 4) measures of genetic variation associated with DNA repair; and 5) combinations of more than one category of assay. The use of such tests in human populations yielded positive and consistent associations between DNA repair capacity and cancer occurrence (with odds ratios in the range of 1. 4-75.3, with the majority of values between 2 and 10). However, the studies that we have reviewed have limitations, including small sample size, "convenience" controls, the use of cells different from the target organ, and the use of mutagens that do not occur in the natural environment. The evolving ability to study polymorphisms in DNA repair genes may contribute to new understandings about the mechanisms of DNA repair and the way in which DNA repair capacity affects the development of cancer.

Occupational exposure to formaldehyde and wood dust and nasopharyngeal carcinoma

OBJECTIVES

To investigate whether occupational exposures to formaldehyde and wood dust increase the risk of nasopharyngeal cancer (NPC).

METHODS

A multicentered, population based case-control study was carried out at five cancer registries in the United States participating in the National Cancer Institute's SEER program. Cases (n=196) with a newly diagnosed NPC between 1987 and 1993, and controls (n=244) selected over the same period from the general population through random digit dialing participated in structured telephone interviews which inquired about suspected risk factors for the disease, including a lifetime history of occupational and chemical exposure. Histological type of cancer was abstracted from clinical records of the registries. Potential exposure to formaldehyde and wood dust was assessed on a job by job basis by experienced industrial hygienists who were blinded as to case or control status.

RESULTS

For formaldehyde, after adjusting for cigarette use, race, and other risk factors, a trend of increasing risk of squamous and unspecified epithelial carcinomas was found for increasing duration (p=0.014) and cumulative exposure (p=0.033) but not for maximum exposure concentration. The odds ratio (OR) for people cumulatively exposed to >1.10 ppm-years was 3.0 (95% confidence interval (95% CI) 1.3 to 6.6) compared with those considered unexposed. In analyses limited to jobs considered definitely exposed, these trends became stronger. The associations were most evident among cigarette smokers. By contrast, there was no association between potential exposure to formaldehyde and undifferentiated and non-keratinising carcinomas. There was little evidence that exposure to wood dust increased risk of NPC, as modest crude associations essentially disappeared after control for potential exposure to formaldehyde.

CONCLUSIONS

These results support the hypothesis that occupational exposure to formaldehyde, but not wood dust, increases risk of NPC. This association seems to be specific to squamous cell carcinomas. Established cohorts of workers exposed to formaldehyde and wood dust should continue to be monitored for NPC and other respiratory cancers. Future studies of NPC should take into account histological type in assessing risk from environmental and host factors.

Immunoreactivity with the anti-MAGE antibody 57B in malignant melanoma: frequency of expression and correlation with prognostic parameters

The melanoma-associated antigen (MAGE) family consists of a number of antigens initially recognized by cytotoxic T lymphocytes, which are currently being investigated for immunotherapy of patients with metastatic melanoma and other tumor types. Expression of MAGE mRNA in melanocytic tumors is said to be restricted to invasive malignant tumors and absent in nevi. Recently, a monoclonal antibody (57B) has become available to examine MAGE protein expression in archival material. In this study, we performed immunohistochemical analysis on 132 melanocytic nevi and 205 melanomas (85 primary cutaneous melanomas and 120 metastatic tumors) to determine the frequency of MAGE expression and to explore a potential correlation with various prognostic parameters. None of the melanocytic nevi and none of the 20 in situ melanomas was immunopositive with the antibody 57B. Immunoreactivity was present in 17 of 65 (26%) primary invasive melanomas of the skin and in 30 of 120 (25%) metastatic tumors. Positive immunostaining did not correlate with tumor stage (P = .66), Breslow thickness (P = .39), Clark level (P = .5), or the histologic type of melanoma (P = .23) but was associated with a brisk infiltrate of lymphocytes involving the vertical growth phase of melanomas (P = .01). Because tumor-infiltrating lymphocytes in melanoma are associated with longer survival, our findings suggest a potential prognostic role for MAGE. Furthermore, the seeming restriction of immunopositivity to invasive malignant tumors suggests a potential diagnostic role for the antibody 57B in confirming the malignant potential of a melanocytic tumor.

A pilot study using nurse education as an intervention to increase skin self-examination for melanoma

BACKGROUND

A pilot study of an intervention using nurse education for skin self-examination (SSE) was conducted in order to determine specific factors that would be important for the design of a larger intervention.

METHODS

Seventy-five subjects completed a pretest, a posttest, a thorough skin examination by a dermatologist, and an educational session by a nurse.

RESULTS

Results showed that the subjects increased the frequency of SSE to a predetermined optimal frequency of once every one to two months. Increases in optimal SSE were associated with increases in knowledge about melanoma (p = 0.006).

CONCLUSIONS

Before intensive campaigns are launched to improve SSE, models incorporating theories of behavioral change should be tested.

Patient knowledge, awareness, and delay in seeking medical attention for malignant melanoma

We investigated the relationship between patient knowledge, awareness, and delay in seeking medical attention for melanoma. The study population was comprised of 255 cases with cutaneous melanoma newly diagnosed during January 15, 1987 to May 15, 1989, who were part of a population-based case control study. Personal interviews were conducted to obtain information on patient's knowledge of melanoma signs and symptoms, skin awareness, delay in seeking medical attention, and related covariates. The adjusted odds ratio for the association between skin awareness and delay was 0.30 (95% confidence interval 0.12-0.71). Odds ratios ranged from 0.43 to 0.81 for knowledge and delay. Awareness of skin changes was associated with a reduced Breslow depth for stage I melanomas. Individuals who are aware of skin changes and abnormalities appear to be less likely to delay seeking medical attention for melanoma. Knowledge of melanoma signs and symptoms may also contribute to a decreased delay in melanoma diagnosis.

Evaluation of factors associated with skin self-examination

Early detection and excision of thin lesions may be important in reducing mortality from melanoma. Periodic skin self-examination may be beneficial in identifying thin lesions. The purpose of this study was to evaluate factors associated with skin self-examination. The study population was comprised of 549 Caucasian residents of Connecticut 18 years of age or older who were selected as controls as part of a population-based case-control study on skin self-examination and melanoma conducted during 1987-1989. Personal interviews were conducted to obtain information on skin self-examination, demographics, history of cancer, phenotypic characteristics, sun exposure habits, and screening and health behaviors. Nevus counts were performed by trained nurse interviewers. Logistic regression was used to model the relationship between the variables of interest and skin self-examination. Female gender was identified a priori as a predictor of skin self-examination, and thus all analyses were stratified by gender. Age, education, and marital status were also identified a priori as important predictor variables and were selected for inclusion in the final models. Skin awareness was a strong factor associated with skin self-examination for both females and males. For females, previous benign biopsy or the presence of an abnormal mole was identified as important for future skin self-examination using our criteria. A family history of cancer, physician examination, and change in diet to reduce cancer risk increased the likelihood of skin self-examination in males but not females. In women, light hair color may increase the likelihood of performing skin self-examination. Older age and college or postgraduate education was associated with a decreased likelihood of performing skin self-examination in both males and females. Identifying factors associated with skin self-examination will enable health care providers to target individuals who may not be performing skin self-examination but who are at increased risk for developing melanoma.

Thorough skin examination for the early detection of melanoma

BACKGROUND

Melanoma is a major public health problem for which early detection may reduce mortality. Since melanoma is generally asymptomatic, this requires skin examination. We sought to evaluate the extent to which the general public has their skin examined by themselves, their partners, or health care providers and the frequency of these examinations.

METHODS

Random-digit-dial survey of adult Rhode Islanders.

RESULTS

Only 9% performed a thorough skin examination (TSE) at least once every few months, although over half of the sample reported conducting skin self-examination "deliberately and systematically." Participants were more likely to perform TSE if they were women and if their health care provider had asked them to examine their skin. Most participants reported that their health care provider never or rarely looked at the areas of their skin in which melanoma is most likely to arise.

CONCLUSIONS

The reported frequency of skin self-examination depends critically on the manner of inquiry. TSE by self or a partner is uncommon, and health care providers do not routinely examine the areas of the skin on which melanomas commonly arise.

Epidermal growth factor, estrogen, and progesterone receptor expression in primary sweat gland carcinomas and primary and metastatic mammary carcinomas

The distinction between primary sweat gland carcinomas and metastatic breast carcinoma to the skin is sometimes difficult. In an effort to improve this discrimination, we compared the immunohistochemical staining pattern of 42 primary sweat gland carcinomas (SGCs) with 30 metastases from breast carcinoma (BC) to the skin, 125 primary BCs, and 30 noncutaneous metastases from BCs. The antibodies used were against the receptors for epidermal growth factor (EGF-R), estrogen receptor (ER), and progesterone receptor (PR). The frequencies of positive staining were as follows for EGF-R: 34 (81%) of 42 SGCs, 5 (17%) of 30 BCs metastatic to skin, 28 (22%) of 125 primary BCs, and 6 (20%) of 30 noncutaneous BC metastases. For ER, the frequencies were 9 (21%) of 42 SGCs and 10 (33%) of 30 BCs metastatic to skin. The frequencies for PR were 8 (19%) of 42 SGCs and 8 (27%) of 30 BCs metastatic to skin. These results suggest that expression of EGF-R may be diagnostically helpful, because it is strongly associated with SGCs when compared with metastatic BCs (P < .0001). This association is also present when ductal eccrine and apocrine types of SGC, which are the histologic subtypes of SGC most difficult to distinguish from metastatic BC, are separately analyzed (P < .001). The frequencies of expression of ER and PR in SGCs and BCs metastatic to skin were not significantly different.

Alpha-tocopherol dietary supplement decreases titers of antibody against 5-hydroxymethyl-2'-deoxyuridine (HMdU)

This study evaluated the effects of vitamin E (alpha-tocopherol) on oxidative DNA damage in a randomized double-blind Phase II chemoprevention trial. Oxidative DNA damage was measured by the level of auto-antibody (Ab) against 5-hydroxymethyl-2'-deoxyuridine (HMdU) in plasma. After the baseline screening, eligible subjects (n = 31; plasma samples from 28 subjects were available for this study) were randomized to receive 15, 60, or 200 mg of alpha-tocopherol per day for 28 days. Biomarkers were measured twice at baseline--on day 1 (visit 1) and day 3 (visit 2)--and twice after intervention--on day 17 (visit 3) and day 31 (visit 4). At baseline, there was a highly significant inverse correlation between anti-HMdU Ab titer and plasma vitamin E level (r = -0.53; P = 0.004; n = 28). Smoking did not affect baseline anti-HMdU Ab titer; however, anti-HMdU Ab titer levels at baseline were significantly lower in subjects with above-median (0.75 ounce/day) alcohol consumption (P = 0.008). No significant change in anti-HMdU Ab level occurred at either visit 3 or visit 4 for subjects on the lowest dose, 15 mg alpha-tocopherol per day. Subjects receiving 60 mg of alpha-tocopherol per day had a significant decrease in anti-HMdU Ab level at visits 3 and 4 compared with baseline (P = 0.049 and P = 0.02, respectively). However, subjects receiving the highest dose, 200 mg/day, had less consistent results: a significant decrease in anti-HMdU Ab level was seen at visit 4 (P = 0.04) but not at visit 3. Our results demonstrate an inverse relationship between alpha-tocopherol and anti-HMdU Abs in plasma; oxidative DNA damage can be modulated by short-term dietary supplementation of alpha-tocopherol in some subjects.

Glutathione S-transferase M1 and susceptibility to nasopharyngeal carcinoma

Genetic polymorphisms for enzymes that metabolize tobacco smoke have been reported to determine susceptibility to several smoking-related cancers, including cancers of the lung, bladder, and head and neck. Glutathione S-transferase M1 (GSTM1) detoxifies benzo(a)pyrene and other carcinogens in tobacco smoke. Approximately 50% of Caucasians lack the GSTM1 gene. Because the most common type of nasopharyngeal cancer (NPC), squamous cell carcinoma, is related to smoking, we sought to determine whether GSTM1 is associated with risk for NPC. Cases (n = 83) were from a population-based study conducted from 1987 to 1993 at five cancer registries in the United States. Random-digit dialing controls (n = 114) were matched to the cases for age, sex, and registry. Subjects participated in a phone interview and blood draw. Absence of GSTM1 was associated with increased risk for NPC (odds ratio = 1.9, 95% confidence interval = 1.0-3.3 for all cases; and odds ratio = 1.7, 95% confidence interval = 0.8-3.5 for squamous cell cases). This relationship was not modified by smoking history, but stronger relationships between glutathione S-transferase and NPC were suggested among subjects who used alcohol more frequently than others, older subjects (50 or more years of age), and women relative to men. These data indicate that absence of GSTM1 moderately increases risk for NPC and add to growing evidence that GSTM1 is a determinant of risk for several smoking-related cancers.

Diet and nasopharyngeal cancer in a low-risk population

Asian studies have reported that risk of nasopharyngeal cancer (NPC) is increased in individuals who frequently consume salted fish, which contains high levels of N-nitroso compounds. As part of a collaborative, population-based, case-control study in the U.S., where the annual incidence of the disease is low, we investigated whether dietary intake of preformed nitrosamines or nitrosamine precursors, or of antioxidants including vitamin C and carotenoids, was associated with altered risk of NPC overall, or of specific histologic subtypes of disease. Cases (n = 133) identified at 5 population-based cancer registries and controls (n = 212) identified through random digit dialing completed a telephone interview and self-administered food frequency questionnaire. Dietary exposures were expressed as quartiles of intake, and odds ratios (ORs) calculated using the lowest quartile of intake as the reference category. Risk of non-keratinizing and undifferentiated tumors of the nasopharynx was increased in frequent consumers of preserved meats, which contain high levels of added nitrites. ORs in the 2nd, 3rd and highest quartile were 1.99, 4.35 and 4.59, although 95% confidence intervals did not exclude 1.0. Risk of differentiated squamous cell carcinoma, but not other histologic types, was significantly reduced in individuals with vitamin C intake above the lowest quartile (ORs 0.30, 0.33 and 0.30 in the 2nd, 3rd and highest quartiles, respectively). This association was markedly stronger among non-smokers and former smokers than among current smokers. Finally, individuals who reported consuming supplemental vitamins were at an approximately 50% reduced risk of NPC. Our results indicate that future studies should consider the effects of dietary risk factors on the risk of specific histologic subsets of NPC, and not assume that the disease is etiologically homogeneous.

Validation of a melanoma prognostic model

BACKGROUND

A "clinically accessible," 4-variable (patient age, patient sex, tumor location, and tumour thickness) prognostic model has been published previously. This model evaluated variables that were commonly available to the clinician. Because models are heuristic, validity of a prognostic model should be evaluated in a population different from the original population.

OBJECTIVE

To evaluate the external validity of this 4-variable melanoma prognostic model.

DESIGN

To estimate the external validity of this model, we used a population-based cohort of individuals with melanoma. We also evaluated a 1-variable model (tumor thickness). Estimates of the external validity of these logistic regression models were made using the c statistic and the Brier score.

SETTINGS AND PATIENTS

A total of 1261 patients with melanoma evaluated in a multispecialty, university-based practice and 650 patients with melanoma from throughout Connecticut.

MAIN OUTCOME MEASURE

Death from melanoma within 5 years of diagnosis.

RESULTS

The c statistics for the 4-variable model were 0.86 (95% confidence interval [CI], 0.83-0.89) for the university-based practice data set and 0.81 (95% CI, 0.75-0.86) for the Connecticut data set. For thickness alone, the c statistics were 0.83 (95% CI, 0.80-0.86) and 0.79 (95% CI, 0.74-0.85), respectively. Brier scores for the 4-variable model were 0.09 (95% CI, 0.08-0.10) and 0.08 (95% CI, 0.06-0.09) and for the 1-variable model were 0.09 (95% CI, 0.08-0.10) and 0.08 (95% CI, 0.07-0.10), respectively. No significant differences exist between the data sets for the 4- and 1-variable models.

CONCLUSIONS

The 4- and 1-variable models are generalizable. The simpler 1-variable model--tumor thickness--can be used with a relatively small loss in accuracy.

Hormonal and reproductive influences and risk of melanoma in women

BACKGROUND

Evidence linking female hormones to the development of malignant melanoma has been contradictory. The purpose of this study was to examine the risk of melanoma in relation to exogenous and endogenous hormonal variables in women, including oral contraceptives, replacement oestrogens, pregnancy, and menopause.

METHODS

Hormonal and reproductive factors were evaluated using data from a personal-interview population-based case-control study of melanoma in women conducted in Connecticut during 1987-1989. Caucasian female incident invasive melanoma cases (n = 308) were confirmed by standardized histopathological review. Caucasian female controls (n = 233) were selected by random digit dialling and frequency-matched on age. Data were analysed using multivariate logistic regression.

RESULTS

Ever being pregnant, age at first pregnancy, current use of replacement oestrogens, ever use of oral contraceptives, duration of use of oral contraceptives, and age at first use of oral contraceptives were not associated with melanoma. Among other variables, cases were more than twice as likely as controls to report a single pregnancy lasting >6 months, but this association lacked a dose-response relationship. Menopause and body mass index were not independently associated with risk of melanoma. However, this analysis did suggest that menopause and body mass index may be interactive risk factors. Melanoma cases were three times more likely than controls to be obese and report natural menopause when compared to thin/acceptable premenopausal women (OR = 3.00, 95% CI: 1.03-8.73).

CONCLUSIONS

These data do not provide strong evidence that hormonal and reproductive factors are associated with risk of melanoma in women, although the few positive results should be explored further.

Sunlamp use and the risk of cutaneous malignant melanoma: a population-based case-control study in Connecticut, USA

BACKGROUND

The relationship between cutaneous malignant melanoma and sunlamp use is examined in a Caucasian population in Connecticut, United States.

METHODS

Cases were diagnosed between 15 January 1987 and 15 May 1987 with a first primary cutaneous melanoma. Controls were obtained from the general population, frequency matched to cases by sex and age, through random digit dialling of Connecticut telephone numbers.

RESULTS

Of all study subjects, 141 (23%) cases and 95 (19%) controls reported ever having used sunlamps. The crude odds ratio (OR) for developing malignant melanoma after ever having used sunlamps was 1.30 (95% confidence interval [CI]: 0.97-1.74). This was reduced to 1.13 (95% CI: 0.82-1.54) after further adjusting for cutaneous phenotype and recreational sun exposure. Those who used more than one type of sunlamp had a threefold higher risk for melanoma compared to never users. Subgroup analyses showed that sunlamp use was associated with a greater increase in risk for melanoma among those who used sunlamps at home and those who were first exposed to sunlamps prior to 1971. The first use of sunlamps before the age of 25 showed somewhat higher risk for melanoma compared to first use later in life.

CONCLUSION

The current study provides limited evidence that use of sunlamps increases the risk of melanoma. For future studies, it is crucial that type of sunlamp, year of first use and amount of exposure are all taken into account. The association between melanoma and tanning with both UV-A and UV-B lamps and tanning under sunlamps early in life merits further investigation.