KLK3 and posterior cortical atrophy: Fania and colleagues, instead, found different MALDI-TOF/MS features in serum associated with PCa in patients with low (≤ 4 ng/mL) or high PSA levels (> 4 ng/mL), a result that could improve the diagnostic accuracy of this tumour marker, in particular by overcoming the false negative rate of PSA [27].