NY-ESO-1 expression and primary melanoma thickness. There was a significant correlation between NY-ESO-1 expression and primary melanoma thickness. All 13 thin melanomas were negative for NY-ESO-1 whereas 4 of the 37 (10.8%) intermediate tumors and 4 of the 11 thick tumors (36.4%) expressed NY-ESO-1 (P = 0.01, trend test).