Among them, positive acute phase proteins A2M, FGG, HPX, SERPING1, and C4A displayed decreased levels, while negative acute phase proteins AHSG and AMBP increased levels in PCa, resulting in down-regulation (PCa vs. BPH z-score= −1.3; PCa vs. BC z-score= −0.8). Here, AMBP is linked to benign prostatic hyperplasia.