Abstract
Purpose :
When the result of prognostic gene expression profile (GEP) testing of a uveal melanoma using the DecisionDx-UM test is reported, the GEP class assigned to the tumor is associated with a discriminant score. The higher the absolute value of this discriminant score, the greater the alleged strength of the assignment of the tumor to the reported GEP class. We designed a study to determine whether this discriminant score holds any prognostic significance above that conveyed by the GEP class assignment.
Methods :
The authors identified cases of posterior uveal melanoma evaluated by fine needle aspiration biopsy prior to or at the time of initial treatment of the intraocular tumor (9/2007 through 8/2015) and divided them initially into GEP Class 1 and GEP Class 2 subgroups. Within each subgroup, they subdivided the cases into four quartiles determined by the discriminant scores associated with the GEP Class assignment. They computed and compared actuarial event rate curves for death from metastatic melanoma for the patients in those four subdivisions of the two GEP Class subgroups.
Results :
The total study group consisted of 560 cases. Of these, 391 (69.8%) were GEP Class 1 and 169 (30.2%) were GEP Class 2. The mean largest basal diameter and thickness of the tumors in the GEP Class 2 subgoup (13.5 mm, 6.6 mm) were substantially larger than these dimensions of the tumors in the GEP Class 1 subgroup (11.1 mm, 5.1 mm). The GEP Class 2 group included a substantially greater proportion of posterior tumors involving the ciliary body (42.6%) than did the GEP Class 1 subgroup (19.2%). The cumulative actuarial probability of death from metastatic melanoma at 6 years was substantially higher in the Class 2 subgroup (0.51) than in the Class 1 subgroup (0.12). The cumulative actuarial survival curves of the discriminant score subdivisions of cases in the Class 2 subgroup were not significantly different from one another; however, the lowest quartile discriminant score subdivision of the GEP Class 1 subgroup exhibited a substantially higher cumulative 6-yr probability of melanoma-related death (0.25) than any of the other three quartile subdivisions.
Conclusions :
GEP Class 1 uveal melanomas associated with a low discriminant score may have a higher probability of metastasis and metastatic death than GEP Class 1 tumors associated with a higher discriminant score.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.