The demonstration of a certain degree of independence of ‘aspecific’ (PCnano1, PCnano2) exosome descriptors from PSA specific (NSFC-exo) one, points to the fact cancer-healthy discrimination obtained by exosome size and number builds upon biological features not strictly related to prostate cancer specificity and thus could be used for ‘general’ cancer screening. Here, KLK3 is linked to Familial prostate cancer.