Tumor Location of Uveal Melanoma and Impact on Metastasis-Free Survival in 1001 Cases.

Background: There is limited literature on tumor location of uveal melanoma (UM) and the relative impact on metastasis-free survival (MFS).

Methods: A review of 1001 consecutive eyes with UM was performed and precise tumor location was identified according to quadrant (5 zones), clock hour (13 zones), anteroposterior (5 zones), and a combination of clock hour and anteroposterior regions (49 zones). Heat maps were constructed for frequency in each zone and Kaplan-Meier estimates for 5- and 10-year MFS was calculated.

Results: The UM quadrant regions included central (macula and juxtapapillary) (18%), superior (19%), nasal (18%), inferior (18%), and temporal (27%). The central region demonstrated smaller UM thickness (p < .01) and diameter (p < .01). The MFS (5- and 10-years) for central region (90%, 86%) was more favorable than other quadrants (p < .01).The UM clock hour regions included central (18%), 1:00 (6%), 2:00 (6%), 3:00 (10%), 4:00 (6%), 5:00 (7%), 6:00 (7%), 7:00 (5%), 8:00 (7%), 9:00 (9%), 10:00 (6%), 11:00 (5%), and 12:00 (8%). The central region demonstrated smaller UM thickness (p < .01) and diameter (p < .01). The MFS (5- and 10-years) for central region (90%, 86%) was more favorable than any clock hour region (p = .03).The UM anteroposterior regions included central (18%), post-equatorial (28%), equatorial (26%), peripheral (13%), and ciliary body (15%). Increasing UM thickness (p < .01) and diameter (p < .01) stepwise were noted with increasing anterior location. The MFS (5- and 10-years) for central region (90%, 86%) was more favorable than other anteroposterior regions (p < .01).A combination of clock hour and anteroposterior regions (49 zones) revealed random distribution with no preferential location. Multivariate regression analysis adjusted for tumor thickness/diameter and proximity to foveola/optic disc showed no benefit of any location.

Conclusions: Across all fundus regions, UM occurred most often in the central region. Uveal melanoma in the central region was smaller in thickness and base and demonstrated more favorable MFS compared to other quadrants, clock hours, and anteroposterior zones. Analysis of the 49 zones showed no benefit of tumor location alone after adjusting for tumor size and proximity to foveola and optic disc.