Melanoma and exposure to sunlight

Cancer mortality in young adults: Italy 1955-1985

Although cancer mortality in young adults accounts for only a small proportion of all cancer deaths, it is important since it provides useful indications of the most likely future trends, and relevant information on the role of exposure to specific, or newer, carcinogens. We, therefore, analysed trends in cancer mortality between 1955 and 1985 among Italian men and women aged 20-44 years. In those three decades, overall cancer mortality declined steadily, by 27% in young women (from 33.8 to 24.7/100,000, world standard) but only by 3% (from 27.3 to 26.4/100,000) among men. The decline for men, however, was 16% from the peak rate of 31.5 reached in 1970-1974. The major underlying component causing the different trends in the two sexes was lung and other tobacco-related neoplasms, which had been considerably on the increase in young men up to the early 1970s, and levelled-off thereafter, while showing no appreciable change in women. The falls were about 50% for stomach cancer in both sexes, and over 80% for cervical cancer. A clear impact of improved treatment was reflected in the substantial declines in Hodgkin's disease, of testicular cancer in the last decade and, possibly, in the favourable trends in cancers of the breast, bone, brain and leukemias over the most recent calendar periods. Only two sites showed appreciable and persisting upward trends: oral cavity in men and skin melanoma in both sexes. They therefore constitute priorities for intervention in the near future.

Anaesthetic agents and the ozone layer

There is an important relationship between the stratospheric ozone layer and the absorption of potentially harmful ultraviolet-B radiation from the sun. Chlorofluorocarbons and halogenated hydrocarbons are commonly used chemicals which are implicated in the depletion of the ozone layer. Of the anaesthetic agents, halothane has the greatest potential for depleting ozone although, when compared with the global use of other chlorofluorocarbons and halogenated hydrocarbons, its current contribution to the problem is relatively small.

Photoaging/photodamage and photoprotection

Exposure to sunlight can produce both acute and long-term effects. Acute changes include erythema, photosensitivity, and immunologic alterations. Long-term consequences include carcinogenesis and photoaging. All effects can be minimized by photoprotection. This article reviews the adverse effects of sun exposure and strategies to reduce photodamage.

Increasing incidence of cutaneous melanoma, ultraviolet radiation and the clinician

Incidence of melanoma is certainly rising all over the world and this observation has been related to a more frequent and prolonged exposure to the rays of the sun. The authors critically review pertinent literature and conclude that descriptive epidemiology of melanoma does not give survival trends and does not support the claim that melanoma is ultraviolet (UV) dependent. Analytical epidemiology has not reached a consensus on this aspect. Experimental data available are also difficult to interpret because there are consistent differences of susceptibility to UV among different animals, among lamps used and methods of measuring employed in various laboratories. Information available shows that the maximal relative biological activity of UV in humans is at about 305 nm. This evaluation greatly depends on (1) thickness of the skin, (2) the quantity and quality of secretions that cover the skin, (3) cleanness of the skin, (4) the latitude, (5) the weather, (6) the hour of the day and (7) the presence of chemical carcinogens in the air and on the skin. The authors stress the importance of the criteria of clinical diagnosis recently introduced in clinical practice and higher public awareness as the causes of the increasing incidence of melanoma.

Solar and UVC-induced mutation in human cells and inhibition by deoxynucleosides

Optimum conditions were established for quantitating the induction of hypoxanthine guanine phosphoribosyl transferase-deficient (HGPRT-) mutants in HeLa cells and in a human amelanotic melanoma cell line (MM96L). Compared at a fluence of equal toxicity (D37, fluence required to decrease cell survival to 37% of unirradiated control), noon sunlight in summer was slightly more mutagenic in MM96L than in HeLa cells (17 and 12 HGPRT- mutants per 10(6) survivors respectively). UVC (predominantly 254 nm) exhibited similar mutagenicity as equitoxic sunlight in HeLa but was 8-fold more effective in MM96L than equitoxic sunlight. Addition of a mixture of deoxyguanosine (20 microM), deoxyadenosine (20 microM), deoxycytidine (100 microM) and thymidine (20 microM) to the culture medium during the 7-day expression period following irradiation gave a 3-fold reduction in the UVC-induced mutation frequency of MM96L but not HeLa cells. The results suggest that these melanocytic cells are highly susceptible to mutagenesis by short wavelength UV, in a mechanism sensitive to deoxynucleosides.

Animal model of conjunctival primary acquired melanosis

A condition clinically identical to human conjunctival primary acquired melanosis (PAM) was induced in 16 of 20 Dutch (pigmented) rabbits after weekly topical 60-microliters applications of a 1% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in acetone. Pigment stippling appeared in the conjunctiva as early as 5 weeks after the initial carcinogen application. Confluent patches of flat pigmentation appeared over the palpebral conjunctiva 18 weeks after the onset of treatment and showed progressive lateral enlargement and darkening. Histologically, a spectrum of changes from increased melanin production and melanocytic hyperplasia without atypia (resembling the human condition of PAM without atypia) through atypical melanocytic hyperplasia (resembling human PAM with atypia) was identified. The development of this model permits further investigations to explore and explain the clinically observed phenomenon of waxing and waning of PAM and its promotion to conjunctival malignant melanoma.

Dysplastic naevi in a population-based survey

The prevalence of dysplastic naevi was studied in a population-based survey of 380 30 to 39-year-old and 50 to 59-year-old non-Maoris in Milton, a small town in the south of New Zealand. Photographs of all pigmented naevi greater than or equal to 4 mm in diameter were taken during the survey and subsequently evaluated by two experienced reviewers. Nine percent of the group (95% CI, 6%-13%) were judged to have one or more dysplastic naevi. Interobserver agreement over the diagnosis of dysplastic naevi was 85% (kappa = 0.55). Dysplastic naevi were associated with higher counts of moles greater than or equal to 2 mm in diameter; 50 or more such moles increased the likelihood of having three or more dysplastic naevi about 40-fold. Naevi judged to be dysplastic were, therefore, relatively common and were associated with increased numbers of common moles.

Descriptive epidemiology of skin cancer in the Swiss Canton of Vaud

Incidence registration and survival data for non-melanocytic skin neoplasms and cutaneous melanoma have been abstracted from the population-based system of the Cancer Registry of the Swiss Canton of Vaud, which has been operating in a particularly favourable environment, since the large majority of cutaneous lesions resected in the area are examined by a pathologist. Among the 5,712 cases registered, 66.7% were basal-cell carcinomas, 20.6% squamous-cell cancers, 9.3% cutaneous melanomas and 3.4% other miscellaneous histological types. The distribution by histological type did not differ appreciably in the 2 sexes, but there were marked inter-sex differences as regards anatomical site. In both sexes, head and neck was by far the commonest localization for non-melanomatous neoplasms (69 to 81% of all incident cases), followed by trunk for basal-cell cancers (18% in males, 15% in females) and upper limb for squamous-cell (10% in males, 17% in females). The distribution of skin melanomas differed considerably between the 2 sexes, by far the commonest site being the trunk for males (45% of cases) and lower limbs for females (40%), followed by head and neck (22% in both sexes). Incidence rates for both basal- and squamous-cell cancers increased with age, and rates were higher in males for each localization except the lower limb. In contrast, incidence for melanoma was higher in females, and incidence rates did not increase with age above 55 years for all sites except head and neck. This can be interpreted in terms of cohort effect, since mortality from melanoma has substantially increased in Switzerland across subsequent birth cohorts. Although this study is essentially descriptive, accurate inspection of these data provides some support for the major aetiological hypotheses of skin carcinogenesis, i.e., the observation that the large majority of basal- and squamous-cell cancers arise on the head and neck confirms the importance of long-term ultraviolet exposure; the relative excess of squamous-cell as compared to basal-cell neoplasms on the upper limb may suggest the role of exposure to other (chemical) carcinogens; and the proportional excess of melanomas on the trunk in males and lower limb in females further indicates that intermittent exposure to sunlight is probably the relevant aetiologic factor for melanocytic skin neoplasms.

Tamoxifen and mastectomy for elderly patients with operable breast cancer

Images

The application of trend surface models to the analysis of time factors in Swiss cancer mortality

To study different temporal components on cancer mortality (age, period and cohort) methods of graphic representation were applied to Swiss mortality data from 1950 to 1984. Maps using continuous slopes ("contour maps") and based on eight tones of grey according to the absolute distribution of rates were used to represent the surfaces defined by the matrix of various age-specific rates. Further, progressively more complex regression surface equations were defined, on the basis of two independent variables (age/cohort) and a dependent one (each age-specific mortality rate). General patterns of trends in cancer mortality were thus identified, permitting definition of important cohort (e.g., upwards for lung and other tobacco-related neoplasms, or downwards for stomach) or period (e.g., downwards for intestines or thyroid cancers) effects, besides the major underlying age component. For most cancer sites, even the lower order (1st to 3rd) models utilised provided excellent fitting, allowing immediate identification of the residuals (e.g., high or low mortality points) as well as estimates of first-order interactions between the three factors, although the parameters of the main effects remained still undetermined. Thus, the method should be essentially used as summary guide to illustrate and understand the general patterns of age, period and cohort effects in (cancer) mortality, although they cannot conceptually solve the inherent problem of identifiability of the three components.

Patterns of invasive melanoma in the Connecticut Tumor Registry. Is the long-term increase real?

The decades-long increase in incidence rates for melanoma has been ascribed to artifactual changes in case ascertainment rather than to true changes in disease risk. In this study, population-based incidence data for invasive cutaneous malignant melanoma from the Connecticut Tumor Registry were categorized into seven age groups and four time periods to examine the pattern of change over four decades. Analyses of age, period, and cohort variables focused on the curvature components, which are estimable functions. Statistical modeling demonstrated the following: (1) incidence rates have increased by birth cohort in both sexes with no requirement for a period variable, regardless of whether data are examined by 10-year, 5-year, or 1-year intervals of diagnosis; (2) this pattern in incidence rates differed from the patterns of change in the two indices of case ascertainment, the proportion of cases confirmed microscopically and the proportion of cases in localized stage, both of which exhibited changes by period of diagnosis rather than by birth cohort; and (3) adjustment for these two indices caused a downward bend in the cohort curve for females but not for males. The results suggested that much of the observed increase for this tumor was real.

Effects of age, birth cohort and period of death on Swiss cancer mortality, 1951-1984

Swiss death certification data over the period 1951-1984 for total cancer mortality and 30 major cancer sites in the population aged 25 to 74 years were analysed using a log-linear Poisson model with arbitrary constraints on the parameters to isolate the effects of birth cohort, calendar period of death and age. The overall pattern of total cancer mortality in males was stable for period values and showed some moderate decreases in cohort values restricted to the generations born after 1930. Cancer mortality trends were more favourable in females, with steady, though moderate, declines in both cohort and period values. According to the estimates from the model, the worst affected generation for male lung cancer was that born around 1910, and a flattening of trends or some moderate decline was observed for more recent cohorts, although this decline was considerably more limited than in other European countries. There were decreases in cohort and period values for stomach, intestine and oesophageal cancer in both sexes and (cervix) uteri in females. Increases were observed in both cohort and period trends for pancreas and liver in males and for several other neoplasms, including prostate, brain, leukaemias and lymphomas, restricted, however, for the latter sites, to the earlier cohorts and hence partly attributable to improved diagnosis and certification in the elderly. Although age values for lung cancer in females were around 10-times lower than in males, upward trends in female lung cancer cohort values were observed in subsequent cohorts and for period values from the late 1960's onwards. Therefore, future trends in female lung cancer mortality should continue to be monitored. The application of these age/period/cohort models thus provides a summary guide for the reading and interpretation of cancer mortality trends, although it cannot replace careful inspection of single age-specific rates.

Migrant and Seasonal Farmworkers in the United States: A Review of Health Hazards, Status, and Policy

Although the occupation and associated living conditions of migrant and seasonal agricultural workers in the U.S. pose exceptional health hazards to the workers and their dependents, relatively few occupational health professionals have been involved with this group. This article examines the basis for this neglect and proposes a definition of the population that should be considered in farmworker health policy. It then reviews existing evidence regarding hazards of four major occupational exposures — pesticides, the sun, injuries, and poor field sanitation — and policies that have been developed to address these hazards. The extremely negative health consequences of farmworker living conditions, which are indirect occupational hazards, are also summarized. Numerous policy, planning, and research recommendations are made. Adequate solutions for this impoverished and powerless group, however, will require significant sociopolitical advances, such as are developing with unionization and other forms of political organization.

Trends in incidence of ocular malignant melanoma in Denmark 1943-1982

All records of ocular malignant melanoma notified to the Danish Cancer Registry between 1943 and 1982 were re-coded, and 1,624 out of 1,650 cases were verified and included in this investigation. The annual number of incident cases increased from about 30 to 50, but the age-standardized incidence rate remained stable at 0.75 per 100,000 in males and 0.60 in females. There was no predilection for one or the other eye in either sex. About 80% of the tumours were located in the choroid, 10% in the ciliary body and iris, 5% in the conjunctiva, and 5% in "multiple regions". The histopathology of the tumours was: epithelioid cell type in 12%, spindle-cell type in 36%, and mixed-cell type in 51%. The stable incidence rates of ocular malignant melanomas were in marked contrast to the 5- and 6-fold increase observed for cutaneous melanomas during the same time period. Possible differences in risk factors are discussed. Similarities and differences between the present data and results from other countries are highlighted.

DNA repair synthesis in fibroblast strains from patients with actinic keratosis, squamous cell carcinoma, basal cell carcinoma, or malignant melanoma after treatment with ultraviolet light, N-acetoxy-2-acetyl-aminofluorene, methyl methanesulfonate, and N-methyl-N-nitrosourea

Fibroblast strains derived from skin biopsies of patients with actinic keratosis (6), malignant melanoma (18), squamous cell carcinoma (11), and basal cell carcinoma (12) were investigated for DNA repair synthesis, with 16 fibroblast strains for normal donors as controls. Cells were exposed to UV light, the "UV-like" carcinogen (Ac)2ONFln, and the methylating carcinogens MeSO2OMe and MeNOUr. Dose-response experiments, which included 10 dose levels, were performed, the data analyzed by linear regression, and the slope of the regression line (term: G0) used as a measure of DNA repair synthesis. The mean experimental variability of G0 of individual fibroblast strains was 9.5%-15.4%, depending upon exposure. For comparison of all cell strains belonging to the same skin malignancy group with those of the control group, G0 values of the individual strains were combined to yield group-specific weighted mean G0 values. In addition, the capacity to incise UV-damaged DNA was measured in 24 cell strains from patients with skin tumors using the alkaline elution technique. For quantitating DNA-incising capacity, the initial velocities of the elution curves were plotted versus the UV dose, and the slope of the resulting regression line was used to obtain the characteristic value E0. The mean experimental variability of E0 of individual strains was +/- 22%. These E0 values were combined to yield weighted mean values of groups. The fibroblast strains in the groups of patients with actinic keratosis and malignant melanoma were found to have normal mean G0 values when DNA repair synthesis was challenged with UV light or one of the three carcinogens. However, the squamous cell carcinoma group exhibited significantly lower mean G0 values after treatment with UV light (82% that of normal donors), (Ac)2ONFln (70%), MeSO2OMe (70%), and MeNOUr (69%). The basal cell carcinoma group showed significantly diminished repair synthesis upon treatment with UV light (81% that of normal donors) and MeSO2OMe (67%). In contrast to these findings, in no skin malignancy group was post UV DNA-incising capacity (E0) significantly diminished, although it should be noted that group sizes were only half as large as for G0 determinations. These data may be interpreted as indicating that DNA excision repair is impaired in fibroblast strains from patients with squamous cell carcinoma and-to a lesser extent-basal cell carcinoma.(ABSTRACT TRUNCATED AT 400 WORDS)

Risk factors for cutaneous malignant melanoma in a northern Italian population

The relationship between cutaneous malignant melanoma (CMM) and the colour of skin, hair and eyes, the extent of sun exposure and reaction to it, education, and the occurrence of skin neoplasms in patients and their families was evaluated in a case-control study of 103 cases of CMM and 205 control subjects hospitalized for acute conditions other than malignant or hormonal disease. A significantly higher risk was associated with fair skin as compared to dark/medium skin (RR = 4.0; 95% CI: 1.5-10.5) and positive family history for CMM (RR = 8.1; 95% CI: 1.0-200.9). CMM seemed to occur more frequently, but not significantly so, in individuals with brown or blond hair, higher education and clinically diagnosed dysplastic naevi. Outdoor occupation and heavy sun exposure in the last 20 years seemed to increase the risk of CMM in sun-exposed sites but to be negatively associated with CMM in normally unexposed sites.

Relation between phenotype and banal melanocytic naevi

In a study of risk factors for the development of melanocytic naevi in relation to the pathogenesis of malignant melanoma 197 white adults were examined by four dermatologists and naevus counts correlated with several other features. Highly significant associations were found between large numbers of banal acquired melanocytic naevi and the ability to tan easily without burning (skin types 3 and 4; relative risk 4.6), brown or hazel eyes (relative risk 3.5), green or grey eyes (relative risk 3.5) and brown or black hair (relative risk 3.7). No significant associations with numbers of naevi were shown for parity or use of oral contraceptives or other steroid hormones. This is the first study to find any relation between melanocytic naevi and phenotypic factors in a white population.

Occurrence of cancer in socioeconomic groups in Sweden. An analysis based on the Swedish Cancer Environment Registry

We wanted to examine the distribution of cancer by socioeconomic group in Sweden. For this purpose the 1960 Census population was followed up for the whole period 1961-79 by means of the Swedish Cancer Environment Registry. Cancer morbidity in five socioeconomic groups was analysed for each of 50 cancer sites. An association was found between several sites and particular socioeconomic groups. For instance, there are elevated rates of lung cancer and stomach cancer among blue collar workers; colon cancer and breast cancer among white collar workers and lip and stomach cancer among self-employed farmers. The overall cancer morbidity was close to the expected levels for all groups except self-employed farmers, who showed a marked deficit.

Sex differences in presentation of cutaneous malignant melanoma and in survival from stage I disease

To explain the improved survival rates of females with malignant melanoma compared with that of males in this region of the United Kingdom (a recognized low incidence area for melanoma), clinicopathologic differences between the sexes of 477 patients presenting with primary melanoma at all stages, were examined between 1961 and 1976. The survival of 356 males and females presenting with Stage I melanoma were also compared, taking death from melanoma as the critical event. The data were analyzed using the Cox multivariate model, which allows several prognostic variables to be considered simultaneously, and enabled the assessment of the effect of, and interactions between, these variables. Female superiority in survival was due to: more lesions on the female lower limb, a site associated with a good prognosis; thinner lesions at presentation in the female; an interaction with age in which females between the age of 50 and 79 years fare significantly better than a similar age group of males. This age/sex interaction has not been observed in high incidence areas. It suggests, therefore, that melanoma may behave differently in different geographical areas.

Melanoma and other tumors of the skin among office, other indoor and outdoor workers in Sweden 1961-1979

Through a record linkage of the 1960 Swedish Population Census and the 1961-79 Cancer Registry it was possible to analyse the occurrence of melanoma and other skin tumours by occupations, classified as either outdoor, office or other indoor work. Office work as compared to other indoor work was associated with risk of melanoma of the covered, but not the uncovered, parts of the body. It is shown that social class is a confounding factor in such analysis, but the elevated risk of melanoma of covered parts of the body among office workers is not entirely due to their higher social class.

Seasonality of presentation of cutaneous melanoma, squamous cell cancer and basal cell cancer in the Oxford Region

The seasonality of presentation of 1019 skin melanomas in Oxford Region 1952-1975, and of 1,523 squamous cell and 4,865 basal cell skin cancers in the region 1967-1975, were analysed using data from the Oxford Cancer Registry. For males and for females, for each of the histologies there was a peak of presentations during July to September. In further subdivisions of the data by age and by skin site, a summer or autumn peak was generally present except where numbers of cases were small. Amplitude of seasonality did not show consistent differences by histology, sex, or skin site, but for both melanoma and squamous cell cancer amplitude was greater for persons aged under 55 years than for older persons. There was no substantial seasonality for presentations of cancers of all non-skin sites in the region. The seasonality of presentation of skin cancers appeared not to be mainly an artefact of the cancer registration process or of organisational aspects of medical care attendance, and only a small proportion of it could be explained as an artefact of the longer term increase in registrations of these cancers. The visibility of skin cancers might have lead to seasonal variation in rapidity of presentation to medical care, for instance for social reasons, or the results might reflect a short induction period effect of exposure to a seasonal insult, perhaps sun radiation, on the aetiology, growth or symptoms of skin cancers; for melanoma there is previous evidence suggesting a short induction period aetiological effect of sun radiation.

Sunlight exposure as risk factor for intraocular malignant melanoma

In a case-control study, we compared 444 patients with intraocular malignant melanoma with matched controls to evaluate the role of exposure to ultraviolet radiation and other risk factors in the pathogenesis of this tumor. Persons born in the southern United States had a relative risk of 2.7 (95 per cent confidence interval, 1.3 to 5.9) as compared with those born in the North. Subjects with brown eyes were protected as compared with those with blue eyes (relative risk, 0.6; 95 per cent confidence interval, 0.4 to 0.8), but complexion and hair color were not important risk factors. Patients with intraocular malignant melanoma were also more likely to have spent time outdoors in their gardens, to have sunbathed, and to have used sunlamps. Rarely wearing hats, visors, or sunglasses while in the sun was a risk factor for the disease (relative risk, 1.9; 95 per cent confidence interval, 1.6 to 2.2). These data suggest that sunlight exposure is an important risk factor for intraocular melanoma.

Migration and death from malignant melanoma

The age-standardized mortality rates for malignant melanoma of the skin in immigrants to New Zealand were compared with those of New Zealand-born non-Maoris. Immigrants from European countries had mortality rates that were generally similar to those prevailing in their countries of origin, although, among immigrants from the British Isles, early age at migration was associated with a mortality rate similar to that of New Zealand-born non-Maoris. In a community survey, British immigrants were not less likely to have had severe sunburn, but had fewer moles, than New Zealand-born non-Maoris. The lower melanoma mortality, and the effect of age at migration, could be mediated by differences in mole frequency.

Risk for cutaneous melanoma in recent Connecticut birth cohorts

Mortality trends suggest that increases in Connecticut incidence for cutaneous melanoma (CM) equal or under estimate increases for the entire country. One-sixth of CM in Connecticut occurs under age 35. In the 1955 birth cohort, modeled incidence rates per 100,000 age-adjusted to the 1960 US population are 38.2 in males and 28.9 in females. These estimated rates for CM rival those for colon cancer (now the third most common malignancy in the United States) and have special implications for young adults.

Cutaneous melanoma in relation to intermittent and constant sun exposure--the Western Canada Melanoma Study

The histories of exposure to sun through occupational, recreational and vacation activities of 595 patients with newly incident cutaneous melanoma excluding lentigo maligna and acral lentiginous melanoma, were compared to those of comparison subjects drawn randomly from the same population and matched for age, sex and province of residence in Western Canada. Significant increases in risk were seen with increasing amount of sun exposure through outdoor activities associated with recreation and vacations; activities likely to involve more intense sun exposure were associated with greater increases in risk. While a moderate amount of occupational exposure was associated with increased risk, greater occupational exposure resulted in no further increase; in men a decrease in risk was seen. These findings were independent of the effects of hair and skin colour, freckles, ethnic origin and socio-economic status. The results suggest that short-term exposure to unusually intense sunlight increases the risk of melanoma, while long-term constant exposure has no effect or may decrease risk. No simple relationship was seen between melanoma risk and total sunlight exposure. This study introduces new methods of assessing different types of sun exposure from retrospective data.

Diagnosis and management of premalignant melanocytic proliferations

The histopathology of melanocytic proliferations in human skin can be defined in a way which allows a rational approach to their management. Early and/or premalignant lesions such as melanocytic hypertrophy, hyperplasia, dysplasia, and atypical hyperplasias are correlated with clinical lesions such as lentigo, compound nevoid lentigo, changes in nevi during pregnancy, and unusual moles seen in patients with the dysplastic nevus syndrome. Clinical management of such lesions may be determined from the pathological process. Hypertrophic and hyperplastic lesions need not be re-excised, although partially removed moles showing junctional hyperplasia may recur clinically. The mildly and moderately dysplastic nevus need only be narrowly removed. Severe dysplasia and melanoma in situ may recur locally as invasive melanoma, and consideration for conservative reexcision is warranted. Dysplastic nevi should be considered to be markers of patients who may develop melanoma. Patients with dysplastic nevi or a family history of unusual moles or melanoma should have continued follow-up, preferably with standardized clinical photographs.

Malignant melanoma in Rome, Italy, 1970-9

An epidemiological study was conducted in the city of Rome and the incidence of malignant melanoma was determined retrospectively for the years 1970-9. All patients had legal residence in Rome and a histological diagnosis of melanoma during that period; only cases of malignant melanoma of the skin (ICD 172, 8th revision) were considered. A total of 17 public and 82 private hospitals were involved in the study with 11 081 and 6127 hospital beds respectively. All the hospitals in the study had one of the following therapeutic and diagnostic facilities: internal medicine, dermatology, oncology, radiology, surgery, plastic surgery, histopathology. Analyses of incidence are based on 500 cases, 237 males and 263 females, collected in the period 1970-9. The data indicate a positive time trend in incidence; the average annual increase is 0.27 cases/year per 100 000. The data show that in a Mediterranean and Latin country such as Italy the incidence of melanoma presents the same ascending trend as that of other Caucasian countries, whether European or not, the slope of the curves is similar for both sexes. The distribution of the primary site for both sexes is closely parallel to that described for all Caucasian populations, the lower limbs being more affected in females and the trunk in males.

Cancer morbidity among workers in the telecommunications industry

A retrospective cohort study of 2918 workers in the telecommunications industry in Sweden recorded the cancer morbidity for the period 1958-79. Cases of cancer were collected from the Swedish Cancer Registry for this period and information on work characteristics was collected for the entire period of employment. The total cancer morbidity was as expected. There was no excess risk of lung cancer but an excess risk of malignant melanoma of the skin was detected (SMR = 2.6, 12 cases). This excess risk was particularly associated with work environments where soldering was practised. Estimates of the SMR became larger with the assumption of a longer induction/latency period.

Sun and malignant melanoma

The incidence and mortality rates of malignant melanoma in Caucasians are increasing rapidly in many countries worldwide. Considerable circumstantial evidence suggests that exposure to solar radiation may play a role in this substantial rise in malignant melanoma. This evidence comes primarily from epidemiologic studies and from the identification of susceptible phenotypes. Despite the increasing data that implicate sunlight as an important factor in the development of certain types of malignant melanomas in humans, the role of solar electromagnetic radiation in the pathogenesis of human malignant melanomas is yet to be determined.

Fibroblasts from patients with hereditary cutaneous malignant melanoma are abnormally sensitive to the mutagenic effect of simulated sunlight and 4-nitroquinoline 1-oxide

Because of a possible etiologic link between mutations and carcinogenesis, we compared fibroblasts derived from skin biopsies of several patients with hereditary cutaneous malignant melanoma and the dysplastic nevus syndrome for sensitivity to the mutagenic and/or cytotoxic effect of broad-spectrum simulated sunlight and of a UV mimetic carcinogen, 4-nitroquinoline 1-oxide (4NQO). The genetic marker was resistance to 6-thioguanine; loss of colony-forming ability was the assay for cytotoxicity. All five strains tested were more sensitive than normal to the killing effect of 4NQO (slopes of survival curves were 2- to 3-fold steeper), but only one strain was hypersensitive to killing by Sun Lamp radiation. Two strains were tested for mutagenicity. The response of each to the mutagenic action of these agents corresponded to its response to cell killing. Both strains were hypermutable after exposure to 4NQO, but only one showed a higher than normal frequency of mutants induced by simulated sunlight. The finding that nonmalignant fibroblasts from patients with a hereditary variant of malignant melanoma are abnormally susceptible to carcinogen-induced mutations suggests that hypersensitivity to mutagens contributes to risk of melanoma in patients. It also supports the somatic cell mutation hypothesis for the origin of cancer.

Risks, survival and trends of malignant melanoma among white and blue collar workers in Sweden

All persons in Sweden, classified as white or blue collar workers in the 1960 Population Census, were followed up for the period 1961-1973 with regard to the occurrence of cancer. The SMRs were calculated for 50 tumour sites and it was found that the crude classification of occupations into white or blue collar workers was particularly important for malignant melanoma risk. The number of malignant melanoma cases among blue collar workers was significantly lower than expected while it was significantly higher than expected among the white collar workers. This was true for men as well as for women. The SMRs were calculated to be 87 and 141 (men) and 79 and 117 (women), respectively. Comparing the relative survival probabilities it was found that white collar workers had a higher probability of survival than blue collar workers. This might indicate that the difference in occurrence could be dependent on early detection as well as differential risk. The incidence of malignant melanoma is increasing faster than any other kind of tumour in Sweden. For the period 1961-1970 the incidence rate increased two-fold for blue collar workers and more than two-fold for white collar workers (men). In absolute terms the white collar workers in the age group 45-64 had an appreciably faster increase in incidence over this period compared to all other groups studied.

Relationship of fluorescent lights to malignant melanoma: another view

In an attempt to determine whether exposure to fluorescent lights may cause an increased risk for developing melanoma, 114 patients with melanoma were compared to 228 age-matched controls. Fluorescent-light exposure, along with 10 other risk factors, was analyzed for its possible relationship to malignant melanoma. No association was found between fluorescent-light exposure and increased risk for acquiring malignant melanoma.

Trends in malignant melanoma of skin in New Zealand

Incidence and mortality rates for malignant melanoma of skin in the New Zealand non-Maori population over the past 30 years were analysed in relation to sex, age, birth cohort and time. In both sexes, the age-standardized incidence rates increased approximately exponentially with time, with an annual increment of 7.5%. The age-standardized mortality rates increased approximately linearly with time, resulting in a two- to three-fold increase over 30 years, as compared with an eight- to nine-fold increase in the incidence rates. Descriptive birth cohort analysis shows different patterns of increase for incidence and mortality rates. The main difference is that, whereas incidence rates have continued to increase in recent birth cohorts, mortality rates have stabilized. The explanation for this difference is uncertain.