The specific biomarker based on PSA-expressing exosomes (NSFC-exo) had a statistically significant (but relatively weak) correlation with exosomes number (PCnano2) only, suggesting that the kind of ‘cancer-related’ information provided by both size and number of exosomes is widely independent to the specific (prostate) cancer type. The gene discussed is KLK3; the disease is Familial prostate cancer.