Abstract
Purpose :
Prior reports on the incidence of uveal melanoma (UM) are derived from large databases where diagnostic accuracy and tumor characteristics cannot be confirmed and where there are unclear population boundaries and demographics. This study utilized the closed patient population of Kaiser Permanente, Northern California (KP) to determine UM incidence. These data are important to provide appropriate allocation of healthcare resources and to determine screening protocols.
Methods :
A retrospective chart review was performed of patients diagnosed with UM by one of two ocular oncologists (MIS, ITP) within KP between October 1st, 2016 and September 30th, 2018. Demographics were compared to the general KP member population. Additional data on visual acuity, tumor characteristics, and treatment modalities were analyzed to define patients that present to ocular oncology and to assess treatment patterns.
Results :
The KP member population served by the ocular oncology service averaged 4.1 million. 79 cases of UM were diagnosed, with an incidence of 9.6 patients per million persons per year. 89% of patients diagnosed with UM identified as Caucasian (OR 1.96); those who identified as Latino, Asian, or African ethnicity had lower incidences (OR 0.32, 0.20, and 0.18, respectively).
The mean thickness of UM at presentation was 3.76 mm and the largest diameter of 23.47 mm. 37.97% (n=30) had tumors thinner than 2 mm with a mean thickness of 1.48 mm and largest diameter of 14.3 mm. All UMs <2 mm thick displayed both subretinal fluid and clumped lipofuscin, confirming UM diagnosis. Incidence was 6.0 per million with tumors <2 mm excluded. The mean age of patients diagnosed with UM was 64 and was higher in patients with tumors <2 mm at 67. By American Joint Committee on Cancer classification, tumors were grouped as T1 50.63% (n= 40), T2 27.85% (n=22), T3 15.19% (n=12), and T4 6.33% (n=5).
Conclusions :
The incidence of UM in our closed population is significantly higher than previously reported. This may be because prior reports have identified UM patients via large, de-identified database reviews and/or from populations of unclear number/demographics, potentially introducing bias. Previous estimates also tended to exclude melanomas <2mm thick; such lesions are considered to be UMs capable of metastases by contemporary ocular oncologists. If such tumors are excluded, the incidence of UM is similar in our population compared to others.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.