Uveal and Conjunctival Malignant Melanoma in Denmark, 1943–97: Incidence and Validation Study

PURPOSE

To study the incidence of malignant melanoma in the ocular region in Denmark during the period 1943-97.

METHODS

The patients were mainly identified through the Danish Cancer Registry. Age-period-cohort modelling of the incidence rates was done based on age at diagnosis, calendar period and birth cohort in 5-year groups and for each gender.

RESULTS

The age-standardized incidence of malignant melanoma in the ocular region was 0.78 for men (N = 1327) and 0.65 for women (N = 1242) per 100,000 person-years. Calendar period and birth cohort had no effect on the incidence in the ocular region or in the topography subgroups choroid/ciliary body and conjunctiva. However, the incidence increased with birth cohort for iris melanomas.

CONCLUSIONS

The incidence of malignant melanoma in the ocular region was stable in contrast to a major increase in cutaneous melanoma in Denmark during the period 1943-97. The incidence of iris melanomas increased substantially, whereas the rate was stable for choroid/ciliary body and conjunctival melanomas.

Comparison of risk patterns in carcinoma and melanoma of the skin in men: a multi-centre case-case-control study

We directly compared risk factors between 214 histologically confirmed melanomas (CMM), 215 basal-cell carcinomas (BCC) and 139 squamous-cell carcinomas (SCC) in a multiple case–case–control study with 349 controls from patients without dermatological disease admitted to the same hospitals. Subjects with fair hair had a significant risk increase for all types of tumours at a comparable level (OR_adj for blonde hair: CMM 2.3; SCC 2.4; BCC 2.3). The effect of pale eyes was significant and similar for CMM and BCC (OR_adj 2.6). Intermittent sun exposure measured in hours spent at beach during holidays was significant for both CMM (OR_adj 2.6 for more than 7000 lifelong hours) and BCC (OR_adj 2.1 for more than 7000 lifelong hours), while SCC exhibited a significant risk increase for chronic exposure to sunlight measured in hours of outdoor work (OR_adj 2.2 for more than 6000 lifelong hours). In the case–case comparison using a multinomial logistic regression model, we found a statistically significant risk difference for pale eyes, and number of naevi in the CMM group, compared to other skin cancers. For intermittent sun exposure, there was a significant risk difference of BCC when compared to the risk of SCC. Factors influencing risk of SCC are different, with chronic exposure to sun playing a major role in causing this type of carcinoma.

A pooled analysis of 10 case-control studies of melanoma and oral contraceptive use

Data regarding the effects of oral contraceptive use on women's risk of melanoma have been difficult to resolve. We undertook a pooled analysis of all case-control studies of melanoma in women completed as of July 1994 for which electronic data were available on oral contraceptive use along with other melanoma risk factors such as hair colour, sun sensitivity, family history of melanoma and sun exposure. Using the original data from each investigation (a total of 2391 cases and 3199 controls), we combined the study-specific odds ratios and standard errors to obtain a pooled estimate that incorporates inter-study heterogeneity. Overall, we observed no excess risk associated with oral contraceptive use for 1 year or longer compared to never use or use for less than 1 year (pooled odds ratio (pOR)=0.86; 95% CI=0.74-1.01), and there was no evidence of heterogeneity between studies. We found no relation between melanoma incidence and duration of oral contraceptive use, age began, year of use, years since first use or last use, or specifically current oral contraceptive use. In aggregate, our findings do not suggest a major role of oral contraceptive use on women's risk of melanoma.

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

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