Incidence of uveal melanoma in Europe.
PURPOSE
To estimate incidence rates of uveal melanoma in Europe from 1983 to 1994.


DESIGN
Incidence analysis of data from cancer registries adhering to the European Cancer Registry-based study on survival and care of cancer patients (EUROCARE) (cases diagnosed from 1983 to 1994).


PARTICIPANTS
Data of 6673 patients with ocular melanoma (as defined by International Classification of Diseases for Oncology morphology codes 8720 to 8780 [melanoma] and International Classification of Diseases 9 (ICD9) codes 190.0 [iris and ciliary body], 190.5 [retina], 190.6 [choroid], and 190.9 [unspecified ocular location]) from 33 cancer registries of 16 European countries.


METHODS
Incidence rate ratios (IRRs) were obtained from a multilevel Poisson regression model.


MAIN OUTCOME MEASURES
Incidence rates and IRRs associated with demographic and geographic variables.


RESULTS
Standardized incidence rates increased from south to north across registries, from a minimum of <2 per million in registries of Spain and southern Italy up to >8 per million in Norway and Denmark. The inclusion of tumors with unspecified ocular location (code 190.9) increased incidence rates in most United Kingdom registries, but not in the other geographic areas, where this code was seldom used for uveal melanomas. Incidence increased noticeably up to age 55 (IRR, 1.46 per 5 years; 95% confidence interval [CI], 1.36-1.57) but leveled off after age 75 (IRR, 0.99 per 5 years; 95% CI, 0.93-1.05), with intermediate levels midway (IRR, 1.18 per 5 years; 95% CI, 1.12-1.23). It was also higher in males (IRR, 1.22; 95% CI, 1.16-1.28). Rates were stable during the study period, but a cohort effect was evidenced, accounting for higher incidence rates in people born during the period 1910 to 1935 (P = 0.005). Incidence increased with latitude (P = 0.008), which explained most differences in rates among areas.


CONCLUSIONS
In this large series of uveal melanomas, we found stable incidence during the years 1983 to 1994. The north-to-south decreasing gradient supports the protective role of ocular pigmentation. European ophthalmologists should develop guidelines to standardize the coding of tumors treated conservatively using the ICD classification to improve the registration and surveillance of uveal melanoma by cancer registries.