Sun exposure predicts risk of ocular melanoma in Australia

Abstract

Previous studies examining sun exposure and ocular melanoma have produced inconsistent results. We investigated this association in a population-based case-control study in Australia. Cases (n ‫؍‬ 290) aged 18 -79 years were diagnosed between January 1996 and July 1998. Controls (n ‫؍‬ 893) were randomly selected from the electoral rolls and frequencymatched to cases by age, sex and state. A self-administered questionnaire and a telephone interview measured sun exposure on weekdays and weekends at 10, 20, 30 and 40 years of age and over the whole of life for specific jobs and recreations. Multivariate logistic regression models of ocular melanoma and sun exposure contained age, sex, region of birth, eye color and measures of ocular and cutaneous sun sensitivity as covariates. Choroid and ciliary body melanoma (n ‫؍‬ 246) was positively associated with time outdoors on weekdays and, less persuasively, total time outdoors but not ambient solar irradiance. Odds ratios increased with increasing exposure to OR 1.8 (95% confidence interval 1.1-2.8) for the highest quarter of sun exposure on weekdays up to 40 years of age for men and women together. The strongest positive associations were for total exposure up to 40 years of age, lifetime occupational exposure and total exposure at about 20 years of age in men; all had odds ratios between 2 and 3 in the highest exposure categories. There was inconclusive evidence for an association between sun exposure and iris (n ‫؍‬ 25) or conjunctival (n ‫؍‬ 19) melanomas. Sun exposure is an independent risk factor for choroidal and ciliary body melanoma in Australia. © 2002 Wiley-Liss, Inc. Key words: ocular melanoma; aetiology; sun exposure; UV radiation; AustraliaThe estimated risks of ocular melanoma associated with personal sun exposure, ambient solar irradiance and use of protective wear have been inconsistent both within and between case-control studies. [1][2][3][4][5][6][7][8][9] However, positive associations with factors less prone to measurement error, such as indicators of sun sensitivity 10 and exposure to artificial sources of UV radiation (e.g., welding arcs and sunlamps), 4,9 suggest a positive association with solar radiation.Possible explanations for past inconclusive results include nonpopulation-based ascertainment of cases and controls, use of qualitative or crude quantitative sun-exposure measures and inadequate control of potential confounding factors, particularly sun sensitivity. Moreover, previous studies collected little or no sun-exposure data for the early years of life. If sun exposure is a risk factor for melanoma of the choroid and ciliary body, the commonest subsites of ocular melanoma, the aetiologically relevant exposure period is probably from birth to the early 20s, when there is some transmission of UV radiation by the crystalline lens to these posterior ocular sites. 11,12 Finally, the unique exposure characteristics of the eye necessitate accounting for personal protective behaviors and environmental factors in estimating ocular sun exposure...

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

“…We relied on self-reported sun exposure history using methods that we have developed over 15 years and used successfully in a number of case-control studies, 23,24,35 both in an extensive, faceto-face interview form and the abbreviated telephone interview form of our study. The face-to-face form has been shown to be reliable on repetition at an interval of about 5 years 25 and the telephone form has been shown to be reliable in comparison with the face-to-face form.…”

“…The face-to-face form has been shown to be reliable on repetition at an interval of about 5 years 25 and the telephone form has been shown to be reliable in comparison with the face-to-face form. 26 Our structured approach to retrospective measurement of sun exposure includes questions about both the pattern and amount of sun exposure and is oriented to personal circumstances or events as recall cues to minimise measurement error. Using the detailed questions, not only is total accumulated lifetime sun exposure hours estimated but, in addition, the components parts can be examined, such as sun exposure on working and nonworking days, or at particular ages.…”

“…We have previously validated the decade years approach as a predictor of total recalled sun exposure. 23 The interviewer explained to the subject that "outdoors" meant hours when they were outside and not under any shade: in this manner, subjects were directed to report hours when they would have been exposed to the sun. The warmer months were defined as being from October to April in the Southern Hemisphere and from March to August in the Northern Hemisphere.…”

“…We constructed separate variables for working and nonworking days sun exposure by summing the reported hours outdoors across the decade years, and a combined working and nonworking days variable as an indicator of total outdoor exposure. We have previously demonstrated the utility of this method for measuring sun exposure [22][23][24][25][26][27] and hereafter refer to outdoor exposure simply as sun exposure.…”

Association of first ocular melanoma with subsequent cutaneous melanoma: Results from the Swedish Family‐Cancer Database

“…[2][3][4][5] Previous data on the role of ultraviolet radiation (UVR) causing OM have been contradictory, 6 but strong evidence was recently reported, particularly for the most common types of OM, chorioid and ciliary body melanoma. 7 Another new study, based on the U.S. Surveillance, Epidemiology and End Results data, reported an increased risk of CM after OM but no increase of OM after CM. 8 Although many studies have analyzed second primary cancers after CM and skin SCC, the results have either shown no increase for subsequent OM, or the studies have been noninformative due to small population size.…”