Abstract
Purpose :
To evaluate the clinical, cytopathological and genomic profile features of diffuse posterior uveal melanomas (PUM) and compare their metastasis free survival with other tumors matched by basal diameter regardless of thickness and thickness regardless of basal diameter.
Methods :
IRB approved retrospective chart review of 550 uveal melanomas biopsied prior to or at the time of treatment. Exclusion criteria included anterior tumors and non-melanoma tumors. Diffuse PUMs were defined as tumors with Largest Basal Diameter (LBD) ≥13 mm and maximal thickness ≤ 20% of LBD. After descriptive statistics and frequencies were calculated, the diffuse PUMs were matched with 2 subsets of tumors of similar thickness or LBD. Kaplan-Meier cumulative metastasis-free survival curves were obtained to compare patient outcomes.
Results :
Seventeen patients with diffuse PUM were studied. The mean patient age was 63.1 years (SD=15.9 years). The mean tumor LBD was 16.8 mm (SD=2.6mm) and mean thickness was 3.0 mm (SD=0.7mm). The median follow-up time of this group of patients was 18.7 months. Fourteen patients had an exclusively choroidal tumor; of these, 8 were subfoveal and 3 were parafoveal, 5 were juxtapapillary, 7 parapapillary, and 5 extrapapillary. All 17 patients were biopsied, 10 at the time of plaque implantation, 4 post-enucleation, and 3 as a separate diagnostic procedure. Tumors cells were categorized as spindle B in 7, mixed spindle and epithelioid in 4, epithelioid in 2, borderline in 2, and insufficient for classification in 2. Twelve tumors were Gene Expression Profile (GEP) class 1 tumor, 4 GEP Class 2, and 1 is still pending. 4-year metastasis-free survival was 42% in the diffuse uveal melanoma subgroup, 66% in the LBD-matched subgroup, and 100% in the thickness-matched subgroup.
Conclusions :
Diffuse PUM seem to represent a distinct category of tumors because despite the fact that most of them have a low risk genomic profile they carry substantially worse metastasis-free survival compared even to other tumors of similar LDB and substantially greater thickness.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.