PDCD1LG2 and carcinoma: According to receiver-operating characteristic (ROC) curve analysis, a serum PD-L2 concentration of 5499 pg/mL represented the optimal cut-off for distinguishing cats with these two subtypes from cats with Luminal A (LA) and Luminal B (LB) carcinomas (specificity: 95.2%; sensitivity: 82.6%; AUC = 0.919).