Abstract
Purpose :
Iris melanoma is the rarest form of uveal melanoma, constituting approximately 3 - 5% of cases. Owing to their low prevalence, treatment of iris melanomas have been centralized to the University Hospital Rigshospitalet in Copenhagen, Denmark. Clinical observations have indicated a notable increase in the incidence of iris melanomas, predominantly attributed to tumors located in the inferior part of the iris. Utilizing data from Danish national registers we set out to determine and analyze the incidence of iris melanomas in Denmark from 1943 - 2022.
Methods :
Patients with iris melanoma were identified from the Danish Institute of Eye Pathology. Filed pathology reports were retrieved and reviewed. Additional patients were found through the Danish Cancer Register and the Danish Cause of Death Register. Clinical records were retrieved and reviewed. Tumor characteristics on tumor location were registered.
Social security numbers (CPR-numbers) were used for retrieval of patient information across databases and information on date of birth, migration status and date of death. Data extracts from the central authority on Danish statistics (Statistics Denmark) were utilized to calculate both crude and age-standardized incidence rates for iris melanoma. Incidence rates were calculated using 5-year intervals spanning from 1943 - 2022.
Results :
Between 1943-2022 a total of 432 cases of iris melanoma were identified, with 293 cases located in the inferior part of the iris, 43 in the superior part, and 81 of mixed location. In 15 cases, tumor location was unknown. Using 5-year intervals, both crude and age-standardized incidence per million increased, from 1.2 - 14.8 and 0.8 - 8.8, respectively. Stratified on tumor location crude and age-standardized incidence rates per million respectively changed from 1.2 - 11.5 and 0.9 - 7.1 for inferior tumors, from 0.0 - 1.7 and 0.0 - 1.0 for superior tumors and from 0.0 - 1.5 and 0.0 - 0.8 for tumors of mixed location.
Conclusions :
From 1943-2022, the incidence of iris melanomas has shown a consistent upward trend, with cases per million individuals rising from 0.8 to 8.8 over 5-year intervals, as determined by age-standardized rates. When stratified by tumor location, it becomes evident that tumors located inferiorly in the iris emerge as the predominant factor contributing to the observed increase in incidence rates, aligning with the clinical experience.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.