Sunlight exposure as risk factor for intraocular malignant melanoma

An epidemiological study of posterior uveal melanoma in Israel, 1961-1989

Trends in the incidence rate of uveal melanoma in Israel during the period 1961-1989 among Jews of various geographical origins and among non-Jews were examined, and found to be stable over time. Based on data of the Israel Cancer Registry, 515 cases were included in the final study population after an independent case-finding ascertainment survey. The average annual incidence rate per million for all Jews was 5.7 for both males and females; the rates for non-Jews were: males 1.6, females 1.3. Incidence rates within the Jewish sub-populations show significant differences. The highest rates by sub-population were for Jews born in Europe or America (7.5 for males and for females), followed by Jews born in Israel (males 6.8, females 6.7); and lowest in Jews born in Africa (males 2.1, females 2.3) and Asia (males 1.6, females 2.8). Jews born in Israel had rates lower than Jews born in Europe and America during the 1960s, but in the 1980s the situation was reversed. Results suggest that rate differences between population groups and over time stem from constitutional factors or from the direct or indirect effect of sunlight radiation, whether early in life or from cumulative exposure.

Risk of ocular melanoma in relation to cutaneous and iris naevi

A case-control study was set up to assess the risk of eye melanoma in relation to the number and type of cutaneous melanocytic naevi and pigmented lesions of the iris. Cases comprised 211 unselected ocular melanoma patients attending the Ocular Oncology Clinic at Moorfields Eye Hospital, London, during November 1990 to October 1991 and diagnosed after August 1986. Hospital and general practice controls (416) were recruited in the North East Thames Region of the UK. Cutaneous naevi greater than or equal to 2 mm in diameter were counted on the skin. Clinically atypical and congenital naevi were recorded separately. Pigmented lesions of the iris were counted. The relative risk for ocular melanoma increased with numbers of atypical naevi and numbers of common naevi. Ten percent of cases but 3% of controls had at least 100 naevi of 2 mm or greater diameter. Seven percent of cases and 0.4% of controls had 4 or more atypical naevi. Pigmented lesions of the iris were significantly more common in cases than controls. Nine percent of cases had the Atypical Mole syndrome (AMS) phenotype compared with 1% of controls. Six cases had concurrent cutaneous melanoma primaries. We conclude that atypical and iris naevi are important risk factors for eye melanoma and that patients with eye melanoma are at increased risk of cutaneous melanoma. Dermatological examination for the AMS phenotype and cutaneous melanoma should be recommended in eye melanoma patients with large numbers of pigmented lesions of the skin or family history of melanoma.

Solar ultraviolet radiation and ocular disease: a review of the epidemiological and experimental evidence

Exposure to solar ultraviolet radiation has been linked, at some point, with more than a dozen eye diseases. Some of these associations are based solely on anecdotes, while others have been subjected to epidemiological investigations. For each eye disease, the evidence for an association with ultraviolet radiation is presented and evaluated. The only eye disease for which there is sufficient evidence of a causal association in humans is photokeratitis. For several eye diseases (climatic droplet keratopathy, pterygium, cataract) there is limited evidence for an association, while for other diseases (uveal melanoma, macular degeneration) there is either little support for an association or inadequate data on which to base an assessment.

Black-white differences in risk for cutaneous, ocular, and visceral melanomas

Fair-skinned individuals have a much higher risk of cutaneous and ocular melanomas than dark-skinned individuals, possibly reflecting a protective effect of melanin against sun exposure. There are some reasons to believe that the effect of sunlight exposure is indirect (i.e., sunlight stimulates growth factor production, which then stimulates melanocytic proliferation, leading to melanoma). Visceral melanomas are extremely rare, and little is known about them. This study used US data on 25,184 melanoma cases to investigate the White-Black ratio for visceral melanoma and did not find a disproportionality similar to that for cutaneous and ocular melanomas. The findings support the hypothesis that the sunlight effect on melanoma is primarily direct.

Are atypical nevi a risk factor for uveal melanoma? A case-control study

Atypical nevi and other potential risk factors for uveal melanoma were studied in 109 uveal melanoma patients and 149 controls. Information concerning employment, medical history, drug use, family history of cancer, excess sun exposure, and blistering sunburn before and after the age of 15 was obtained. A total skin examination was performed and skin type, hair color, eye color, freckles, actinic damage, the total number of common acquired nevi, and the number of clinically atypical nevi were noted. More atypical nevi were found in uveal melanoma patients than in controls (age- and sex-adjusted odds ratio of 2.9 [95% confidence interval 1.2-6.3] for one or two atypical nevi versus none; odds ratio of 5.1 [95% CI 1.3-20.0] for three or more atypical nevi versus none). Light skin types and freckling also prevailed in uveal melanoma cases. In our study, atypical nevi are more common in uveal melanoma patients than in controls. Further studies will have to indicate whether risk factors comparable to those for cutaneous melanoma really exist for uveal melanoma.

Mortality study on a cohort of Italian licensed pesticide users

This study describes the mortality experience in a cohort of 23,401 farmers, residing in southern Piedmont, Italy, and licensed to use pesticides. From 1970 to 1986 the cohort included 340,794 person-years and 2683 deaths were observed. A strong attenuation of the death risk was found due to the healthy worker effect (seen as an active role in the application for the license by the members of the cohort) and due to the limited comparability of the cohort with respect to the reference population. The standardized mortality ratios (SMRs) were remarkably < 100 for all causes (SMR = 59; 95% confidence interval = 57-61) and for all tumors (SMR = 60; 95% CI 55-64), but they increased with the increasing duration of the follow-up. A risk increase was observed with respect to melanomas and eye tumors in the entire cohort and lymphoma and tumors of the connective tissue in the subcohort of subjects living in villages with mainly arable land.

Knowledge of sunlight effects on the eyes and protective behaviors in the general community

The knowledge of sunlight effects on the eyes and protective behaviors was assessed in the general community of Brisbane, Australia. Five hundred people were systematically sampled and surveyed via a telephone questionnaire. Of the participants, 279 (56%) were female and 258 (52%) were aged 40 years or less. Levels of knowledge were found to be lower in the older subjects, those with dark complexions and outdoor workers. Most were unaware of specific ultraviolet light related eye diseases such as cataract, pterygium and eye cancer. Three hundred and ninety (78%) wore sunglasses > 10% of the time while outdoors during the day; the most common reasons for wearing included protection from glare in 254 (65%) and driving in 60 (15%). Ninety-six (19%) never wore sunglasses, the most common reasons being inconvenience in 16 (17%), thought unnecessary in 16 (17%) and uncomfortable in 13 (14%). Promotion of sun protection to prevent ultraviolet light related diseases should include information on the eye. This information is important for establishing preventative behaviors and the selection of optimal eye protective measures.

Uveal melanoma: is solar ultraviolet radiation a risk factor?

Age-standardized mortality rates for cancers of the eye among adults in England and Wales are compared with those for cutaneous malignant melanoma. While cutaneous malignant melanoma rates have increased three-fold since 1950-54, rates for cancers of the eye have remained relatively constant over the same period. Collectively, the inconclusive findings of case-control studies for an association between exposure to ultraviolet radiation and uveal melanoma, the lack of supporting dosimetry data, together with the lack of an upward trend in mortality rates for cancers of the eye, suggests that exposure to ultraviolet radiation may not be a major factor in the etiology of uveal melanoma.

Design and methods of a clinical trial for a rare condition: the Collaborative Ocular Melanoma Study. COMS Report No. 3

Investigators who conduct clinical trials of treatments for uncommon conditions face special challenges regarding trial design and execution in addition to the challenges faced by all clinical trial investigators. The Collaborative Ocular Melanoma Study (COMS) currently consists of two multicenter, randomized controlled clinical trials designed to investigate the efficacy of radiotherapy compared to surgery in prolonging the survival of patients with choroidal melanoma, a rare intraocular cancer. Patients with unilateral choroidal melanoma classified as "medium" in size are randomized with equal probability to either enucleation (removal of the eye) or radiation delivered to the tumor by means of a radioactive "plaque" attached by sutures to the scleral surface of the eye over the base of the tumor. Patients with large tumors are randomized with equal probability to either enucleation or a 5 day course of external beam radiation therapy followed by enucleation. Time to death is the primary outcome; patients will be followed for at least 10 years or until death. Quality assurance mechanisms for evaluation, treatment, and follow-up have been implemented. This paper describes the design and methods of the trials, highlights the challenges associated with implementing and conducting the study, and summarizes the current status of the study.

Ocular melanoma in childhood

A case of primary ocular melanoma of the iris in a 10 year old girl is reported. Primary melanoma of the eye is exceedingly rare in childhood. The incidence and risk factors for ocular melanoma are discussed and possible reasons why this tumour is so uncommon in younger age groups are considered.

Tumor progression in ocular melanomas

The term ocular melanoma refers to a heterogeneous group of cancers of melanocytic origin. The precursor of most cases of conjunctival melanoma is known to ophthalmologists as primary acquired melanosis. This condition passes through well-defined stages of tumor progression. Although tumor progression is not obligatory, as a conjunctival melanocytic lesion acquires new biologic properties it is more likely to progress further. Although junctional nevi are seldom encountered beyond childhood and primary acquired melanosis usually develops in middle-aged individuals, these two conditions may be histologically indistinguishable. Most junctional nevi eventually show evidence of differentiation, whereas nearly half of the cases of primary acquired melanosis with atypia progress to melanoma. Therefore, it is possible that aging may modulate the capability of certain clonal proliferations to differentiate. Uveal melanocytes normally reside in mesenchyme, so that the traditional histologic criterion for establishing the diagnosis of most melanomas--breach of an epithelial basement membrane--does not apply. Because uveal melanomas are not easily accessible to incisional biopsy (without disruption of vision), only two points in the spectrum of tumor progression are defined clinically: nevus and melanoma. Experimental evidence suggests that a spectrum of atypical melanocytic proliferations separates benign nevi from melanomas capable of generating metastases. Unlike conjunctival melanomas that spread first to regional lymph nodes, choroidal and ciliary body melanomas preferentially spread first to the liver and are examples of organ-specific metastases.

Cytogenetic analysis of uveal melanoma. Consistent occurrence of monosomy 3 and trisomy 8q

BACKGROUND

The genetic alterations associated with the pathogenesis of uveal melanoma have not been determined. To address this issue, the authors performed a prospective cytogenetic study of 35 uveal melanomas, including 23 primary untreated tumors and 12 tumors that were removed after local radiation therapy.

METHODS

Representative tumor tissue was processed by established methods for histopathologic and cytogenetic studies. Tumor cells were disaggregated and established in short-term culture; metaphases were prepared by standard methods for karyotypic analysis.

RESULTS

Successful analyses were achieved in 27 of the tumor specimens, including 20 of 23 tumors not exposed to radiation and 7 of 12 tumors exposed to radiation. All of the tumors had an abnormal karyotype. Recurrent chromosomal abnormalities detected in the tumors not exposed to radiation included monosomy 3 (13 of 20), trisomy 8 or 8q (11 of 20), loss of a sex chromosome (10 of 20), and loss of 6q (8 of 20). The tumors previously exposed to radiation were characterized by more complex changes, with monosomy 3 and trisomy 8q detected in three cases each.

CONCLUSIONS

Uveal melanoma is characterized by monosomy 3 and trisomy 8q in most cases. These findings, which are supported by data from other investigators, provide compelling evidence that loss of gene sequences on chromosome 3 and duplication of gene sequences on chromosome 8 are implicated in the genetic alterations associated with uveal melanoma and offer a basis for additional molecular genetic investigations.

Occupation and risk of uveal melanoma. An exploratory study

BACKGROUND

Little is known about the cause of uveal melanoma, the most common primary intraocular malignant lesion in adults. This population-based case-control study evaluated occupational exposures.

METHODS

One hundred ninety-seven newly diagnosed cases of uveal melanoma participated. Approximately two control subjects matched for age, sex, and telephone exchange area were selected for each case by random-digit dialing. Data were collected by a structured telephone interview. Two systems of occupational coding were used: an occupation-exposure linkage system and the Bureau of Census data. Conditional logistic regression for matched studies was used to examine various occupational exposures while controlling for previously reported potential confounders and for family income. The occupation-exposure matrix was used to define clusters of cases exposed to a particular chemical group from various occupations.

RESULTS

Odds ratios were elevated for agriculture and farming work for both industry and occupation; this was consistent across both classification systems. Elevated odds ratios also were found for occupations involving machine operations, fabrication, assembling, equipment cleaning, and exposure to metal industries. Exposure to alkylating agents and phenols was associated with a lower risk compared with all other exposures. Several self-reported exposures also were studied. Exposures associated with elevated odds ratios were inks, insecticides, gases, radioactive substances, polybromated biphenyls, and chemical solvents.

CONCLUSIONS

This exploratory study suggests various occupational associations for uveal melanoma and areas for future research.

An abbreviated assessment of ocular exposure to ultraviolet radiation

Individual behaviour has a very large effect on determining the exposure of the eye to solar radiation. To be able to examine the relationship between ocular exposure to ambient ultraviolet radiation and ocular disease, a model was developed previously that assessed cumulative ocular exposure from individual information on work and leisure activities. In this paper, we present a simplified version of the model that uses data on exposure during the middle of the day (9 a.m. to 3 p.m. solar time) during the northern 'summer' months (April to September). The ocular exposure determined by the simplified model is highly correlated with the full model (r = 0.98) and the simplified model predicts 62% of the total ocular exposure. This model should be useful for future epidemiologic studies of sun exposure and eye disease.

Clinicopathologic spectrum of primary uveal melanocytic lesions in an animal model

BACKGROUND

Currently, there are no animal models of primary uveal melanoma in an eye large enough to allow documentation of the clinical evolution of the lesion by either funduscopy or fundus photography.

METHODS

The authors induced primary uveal melanocytic lesions in the eyes of Dutch (pigmented) rabbits using a two-stage carcinogenesis protocol involving initiation with 4 weekly topical applications of 10 microliters of a 1% solution of 7,12-dimethyl-benz[a]anthracene (DMBA) in acetone (21 eyes) followed by 12 weekly topical applications of a 10 microliters solution of either 0.25% or 0.5% croton oil in acetone. They also investigated the effect of initiation with DMBA without promotion and the effects of chronic topical exposure to acetone and proparacaine.

RESULTS

Exposure to DMBA followed by promotion with croton oil in either concentration was the most effective means of inducing clinically detectable fundus lesions. Histologically, a spectrum of melanocytic proliferations developed including benign nevi, nevi with varying grades of cytologic atypia, and clusters of confluent atypical melanocytes that may represent early melanomas. Although clinical regression of fundus lesions was noted in eight eyes after promotion had been stopped, five of these eyes showed unequivocal histologic evidence of a residual uveal melanocytic lesion. Chronic ocular irritation is capable of inducing cytologically benign subclinical uveal melanocytic proliferations.

CONCLUSIONS

The conventional classification of human uveal melanocytic lesions includes only nevi and melanomas, but a comparison of the results of this study with descriptions of human uveal melanocytic nevi suggests the existence of a spectrum of intermediate atypical precursor lesions in humans.

Properties and function of the ocular melanin--a photobiophysical view

This paper reviews the biosynthesis and physicochemical properties of the ocular melanin. Age-related changes of melanin granules and the corresponding formation of lipofuscin pigments in the retinal pigment epithelium (RPE) are also described. Adverse photoreactions of the eye and, in particular, light-induced damage to the RPE-retina are reviewed in relation to the ocular pigmentation. A hypothesis on the photoprotective role of the RPE melanin is presented that is based on the ability of the cellular melanin to bind redoxactive metal ions. Since bound-to-melanin metal ions are expected to be less damaging to the pigment cells, it is proposed that sequestration of heavy metal ions by the RPE melanin is an efficient detoxifying mechanism. It is postulated that oxidative degradation of RPE melanin may lower its metal-binding capability and decrease its anti-oxidant efficiency. Cellular and environmental factors that may contribute to possible oxidative damage of the RPE melanin are discussed in connection with the etiology of age-related macular degeneration.

Pregnancy and sex steroid hormone effects on nevi of patients with the dysplastic nevus syndrome

Female patients with the dysplastic nevus syndrome who were pregnant or taking sex steroid hormones were prospectively studied to evaluate the effectiveness of photography and close clinical follow-up in detecting nevus change or melanoma development. Seventeen patients, who served as their own controls, were studied during 22 pregnancies. Twenty-four patients who used oral contraceptives and seven who took hormone supplements were similarly studied. This clinical management method provided timely biopsy of changing nevi with a small number of biopsies required per patient. One melanoma occurred during pregnancy, but neither patients who were taking sex steroid hormones nor those in the control groups had melanomas. The rate of nevus change observed clinically was 3.9 times higher when patients with dysplastic nevus syndrome were pregnant than when they were not, whereas no differences were observed whether or not women took oral contraceptives or hormone supplements. The rate of histologically proven dysplastic nevi that changed was 2.0-fold higher when women were pregnant; 1.4-fold higher with the use of hormone supplements and 1.1-fold higher with the use of oral contraceptives. These preliminary data suggest pregnancy and hormone supplements may be temporally associated with an increased rate of dysplastic nevus change.

No N-ras mutations in human uveal melanoma: the role of ultraviolet light revisited

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No excess prior cancer in patients with uveal melanoma

To determine whether there were more prior cancers in uveal melanoma patients than in a geographically matched control group, the authors compared the history of prior cancer in 407 uveal melanoma patients who lived in the western United States with that of 870 control subjects. Control subjects were selected by random digit dial and frequency-matched for age at diagnosis of patient, race, and sex. Fifty-one (12.5%) patients and 86 (9.9%) control subjects reported skin cancers whereas 25 (6.1%) patients and 47 (5.4%) control subjects reported other cancers. No statistically significant elevated estimates of relative risk (RR) were found for uveal melanoma with history of skin cancer in either men (RR = 1.4, 95% confidence interval (CI) = 0.87-2.3) or women (RR = 1.1, 95% CI = 0.58-2.0), or with history of other prior cancer in either sex (men, RR = 1.0, 95% CI = 0.42-2.2; women, RR = 1.1, 95% CI = 0.55-2.1). Data from this study do not support an association between prior cancer and increased risk of uveal melanoma.

Urban and rural factors in the aetiology of cancer

The incidence of cancer, or the mortality attributed to it, has been compared in urban and rural residents in 13 populations. In each case, the incidence (or mortality) has been higher in the urban areas in each sex, the ratios varying from a minimum of 1.03 to 1 in men in Japan to 1.63 to 1 in men in Denmark. Examination of 26 separate types of cancer showed that 23 tended to be more common in towns, 1 (myeloma) to be evenly distributed, and 2 (cancers of the lip and eye) to be more common in the countryside. The urban excess was greatest for cancers of the bladder, larynx, liver, lung, mouth and pharynx, and oesophagus, and least for leukaemia and non-Hodgkin's lymphoma. It is concluded that differences in personal behaviour (cigarette smoking, alcohol consumption, sexual promiscuity, exposure to ultraviolet light, type of diet, and family size) are the principal factors responsible for the urban excess. Other factors include general atmospheric pollution, occupational hazards, genetic differences in susceptibility, and artefacts of diagnosis and recording. The rural excess was marked for cancer of the lip in both sexes, but less marked and clearly evident only in men for cancer of the eye. Three-quarters of eye cancers are melanomas and the excess incidence in rural areas provides some weak support for the idea that exposure to sunlight contributes to the production of the disease.

Effects of ultraviolet radiation

Ultraviolet radiation from high-intensity sources has well-known acute effects on the eye and skin, consisting primarily of photokeratoconjunctivitis and sunburn, which are enhanced in the presence of photosensitizing agents. Long-term elevated exposure to low-level ultraviolet radiation is also responsible for an increased risk of squamous- and basal-cell carcinomas; probably responsible for an increased risk of cortical and posterior subcapsular cataracts, pterygium, and cutaneous melanoma and intraocular melanoma and possibly responsible for immunologic effects of clinical significance.

Evaluation of prior primary malignancy as a determinant of uveal melanoma. A case-control study

To examine whether individuals with a history of malignancy are at increased risk for uveal melanoma developing, the authors conducted a case-control study comparing history of prior malignancy among 197 New England cases and 385 matched controls identified by random digit dialing (RDD), and 337 cases residing within the United States and 800 sibling controls. Estimated relative risks for uveal melanoma associated with nonskin cancers were 1.2 (95% confidence interval [Cl], 0.61-2.3) and 0.9 (95% Cl, 0.49-1.5) for RDD and sibling comparisons, respectively. Prior skin malignancy (melanoma and basal or squamous cell types) tended to increase the estimated risk in both groups (case/RDD comparison: relative risk, 1.5; 95% Cl, 0.67-3.5 and case/sibling comparison: relative risk, 1.7; 95% Cl, 0.93-2.9). Among females, history of a malignancy was associated with a higher risk in the case/RDD comparison only (relative risk estimate, 2.2; 95% Cl, 0.97-5.1). These results suggest that the association of prior malignancies with uveal melanoma is weak. Cutaneous malignancies and uveal melanomas may share some common risk factors.

Choroidal malignant melanoma in an albino

This is the first report of an amelanotic melanoma arising in the unpigmented choroid of a tyrosinase-positive oculocutaneous albino (TPOCA). Melanosomes within the tumour showed a maturation arrest in the unpigmented type II (premelanosome) phase. Other neural crest derived melanocytes in iris and choroid showed similar limited melanogenesis. The neuroectodermally derived melanocytes of the iris, ciliary body, and retinal pigment epithelium (RPE) contained mature melanosomes, though clinically the RPE was pale. The significance of this tumour arising in an albinotic eye is discussed.

The biological effects of UV-B on the eye

The adverse effects of ultraviolet-B (UV-B) radiation on the eye have been suspected but only recently have they been quantified by epidemiologic studies in humans. These studies became possible as methods to qualify individual ocular UV-B exposure were developed. A consistent dose-dependent association between ocular UV-B exposure and two common types of cataract (cortical and posterior subcapsular) has been shown. Although suggested by experimental studies, at present, evidence does not exist to link UV-B exposure to senile macular degeneration. Ocular exposure to UV-B is also associated with several corneal changes, pterygium, climatic droplet keratopathy, and acute photokeratitis (snow blindness). Significant reduction in ocular UV-B exposure results from the use of eyeglasses and hats.

Other cancers in uveal melanoma patients and their families

To determine associations with other cancers, 400 consecutive uveal melanoma patients examined at Wills Eye Hospital between 1984 and 1985 were surveyed regarding personal and family history of cancer. Responses were received from 333 (83%). Sixty patients reported 43 nonbasal cell second primary cancers, which were confirmed pathologically or by physician records. The overall prevalence of nonbasal cell cancers diagnosed in uveal melanoma patients by December 1985 was over two times greater than the expected prevalence, based on the Connecticut Tumor Registry data for an age- and sex-matched population. Gynecologic cancers tended to be more common in uveal melanoma female patients than in the comparison population. Although the observed prevalence of cutaneous melanoma was not significantly greater than expected, three cases with both primary cutaneous and uveal melanoma were reported. Family histories of cutaneous melanoma were confirmed in 14 patients, and uveal melanoma in two patients. Data suggested that the overall cancer prevalence in uveal melanoma patients may be increased, that hormonal factors may play a role in the genesis of this malignancy, and that there may be a link between cutaneous and uveal melanoma.

Epidemiology and control of melanoma in white populations and in Japan

In white populations living at moderate or low latitudes, melanoma has become one of the most common tumors in young adults. Epidemiologic studies show a complex association with sun exposure. Risk is related positively to the levels of exposure typical of the place of residence, and also to personally controlled exposure, with the maximum risk being related to acute intermittent exposure. Risk also varies with pigmentation, family history of melanoma, and the presence of benign and of dysplastic nevi. The following methods of control of melanoma in such populations are discussed: the most effective methods depend on early diagnosis; primary prevention appears difficult and requires evaluation; identification of very high-risk subjects on the basis of family history and dysplastic nevi will affect only a very small proportion of melanomas; the use of simpler methods to identify high-risk subjects is explored. In Japan, melanoma is comparatively rare, but increasing as rapidly as elsewhere. The incidence rate of acral lentiginous melanoma appears similar to that in whites, comprising a large proportion of melanoma in Japan. Control programs cannot be designed rationally, since basic information on the occurrence, presentation, and survival of melanoma in Japan is lacking. Some specific research questions are suggested.

Increased incidence of malignant melanoma of the skin in workers in a telecommunications industry

In 1982 physicians at a hospital melanoma clinic in Montreal noticed that among their patients there had been seven men working in a single telecommunications company. This raised suspicions that working in that industry might be associated with development of malignant melanoma of the skin (MMS). A preliminary gross comparison with general population rates indicated that there was an increased risk in this working group. To estimate the risk of MMS more accurately, a standardised incidence ratio (SIR) was calculated based on the rates of MMS in the local population of the Greater Metropolitan Montreal Area for the years 1976-83. During that period, among workers in all plants for the company, 10 male cases of MMS were observed for an expected number of 3.7 (SIR = 2.7; 95% CI = 1.31-5.02). No cases were observed among female workers (expected = 1.3). The excess was significant among cases with a short latency (less than 20 years since beginning of employment). There was no apparent pattern of exposure based on job titles or departments.

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Photoimmunology: the mechanisms involved in immune modulation by UV radiation

Ultraviolet radiation (UVR) may be the most prevalent agent that man encounters in his environment. As a result, certain biological adaptations take advantage of the beneficial effects of UVR exposure, e.g. the photoactivation steps involved in vitamin D metabolism. In this regard, UVR plays an important role in maintaining our good health; however, it must be noted that UVR is potentially the most harmful naturally occurring agent in our environment. Thus, it appears that several mechanisms have evolved to protect us against the detrimental effects of UVR overexposure. Although epidermal melaninization or "tanning" may be the most obvious example of these processes, we would argue that adoptive mechanisms within the immune system also provide protection against UVR-induced skin damage. It is now known that UVR affects the distribution and functional activities of various immunocompetent cells within the skin, as well as modifying the production of inflammatory and hematopoietically active cytokines. This review will focus on the known mechanisms involved in the immune modulatory effects of UVR and how adoptive immune responses to UVR-induced skin damage contribute to specific pathological processes.

Familial uveal melanoma

The cause of uveal melanoma is unknown. In a few cases, however, factors are found in association with the disease which may play some part in the aetiology. One such factor is inheritance. Twelve families have been reported with adequate documentation during the last century in which two or more members have had uveal melanomas. At least some of these may be the result of an inherited disorder. On available data inheritance is most likely autosomal dominant with partial expressivity or incomplete penetrance. This report describes two more families each of which have two members with uveal melanomas.

Place of birth and incidence of ocular melanoma in the United States

To examine whether or not being born in the southern United States is associated with an increased risk of ocular melanoma, the distribution of State of birth of 763 patients (White, not of Spanish origin) with ocular melanoma diagnosed between 1973 and 1984 and identified by 9 population-based cancer registries participating in the Surveillance, Epidemiology, and End Results program, was compared to the distribution of State of birth of the underlying population of the regions served by these registries. The incidence of ocular melanoma among persons born in the southern United States was nearly the same as that among persons born in the north, after adjustment for age, sex, and residence at diagnosis (Incidence Ratio = 1.1, 95% C.I. 0.8, 1.5). Comparisons of the risk of ocular melanoma between persons born in States with high and low levels of solar radiation yielded similar results, and a trend with increasing solar radiation was observed only among females. These findings do not support the hypothesis that exposure to the sun early in life is a major risk factor for ocular melanoma.

Epidemiologic aspects of uveal melanoma

Although the underlying cause or causes of uveal melanoma have yet to be elucidated, important insights may be gained by examining the epidemiologic features of the disease. Uveal melanoma is an uncommon cancer with an incidence of only six cases per million population per year. It is most often diagnosed in the sixth decade and is somewhat more common in males. Apart from sporadic reports of family clusters, uveal melanoma is not considered an inherited disease. Whether some environmental exposure triggers the development of uveal melanoma remains an open question. Sunlight has been proposed as an environmental risk factor because sunlight is known to cause melanoma of the skin and both diseases are rare in nonwhite races. Unlike cutaneous melanoma, however, rates have not been increasing over time and do not vary by latitude. This paper evaluates the available evidence for sunlight and other potential risk factors for uveal melanoma, highlighting areas requiring further research.

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.

Cancer and other causes of death among Wisconsin farmers

Computerized mortality listings for Wisconsin for 1968-1976 were used in proportional mortality ratio (PMR) and proportional cancer mortality ratio (PCMR) analyses to evaluate mortality patterns among Wisconsin farmers. Examination of PCMR trends by per capita county level of agricultural production was limited to the youngest birth cohort (1905-1958) and cancer sites associated with farming exposures in either the present or previous analyses. Among all Wisconsin farmers, significantly decreased PMRs were seen for tobacco- and alcohol-related causes of death, while excesses occurred for accidental causes, asthma, and cancer of the stomach, prostate, eye, and lymphatic and hematopoietic systems. Elevated PCMR's for leukemia and all lymphopoietic cancer and cancers of the stomach, rectum, eye occurred in farmers born 1905-1958, while deficits were observed for cancer of the pancreas and the category, "all other cancers." Increases in PCMR's with level of various agricultural activities were largely associated with cancers of other lymphatic tissue (2/3 of which were multiple myeloma) and the rectum. Certain agricultural exposures were also positively associated with deaths due to cancers of the prostate, brain, lymphosarcoma and reticulosarcoma, and all lymphopoietic cancers. No positive PCMR gradients were observed for leukemia and malignancies of the stomach and eye. Modern chemical practices in farming may account for some of the patterns noted.

Sun protection in well-child care: results of a survey of Florida pediatricians

Chronic sun exposure has been linked to induction of skin cancers including melanoma and aging changes of the skin, has an adverse effect on certain diseases such as lupus erythematosus and is responsible for drug-induced phototoxic reactions. A majority of an individual's lifetime sun exposure may occur during childhood, and thus early photoprotection is desirable. We conducted a written survey of Florida pediatricians regarding their inclusion of sun protection information as part of routine well-child care. The results indicated that a majority of the pediatricians have awareness of the need for parent and patient education about sun-related issues, and most (65%) requested further information and educational materials. This study suggests that expanded educational efforts concerning sun-related health hazards and sun protection would be desirable for physicians involved in pediatric care, for parents, and for children.

Experimental ocular malignant melanoma in Sinclair swine

An animal model of malignant melanoma of the eye was established by transplanting a cell suspension from cutaneous melanomas into the anterior chamber of the eye in Sinclair Farm miniature swine. The frequency of tumor takes in the eye was increased from 8.9% to 22% by treating the animals simultaneously with subconjunctival triamcinolone acetonide. As an animal model for hematoporphyrin derivative--photoradiation treatment of human malignant melanoma of the eye, this does not appear to be a good research tool because of the sporadic incidence of tumor takes, the rapid growth of tumor within the eye causing glaucoma, and the dark iris pigmentation of successful tumor takes, which hides extensive underlying ciliary body tumor.