Use of PSA-IgM to demonstrate the possibility to reduce significantly the number of negative prostatic mappings has been validated by a multicenter prospective clinical study on 421 patients (213 PCa cases, 208 BPH controls) who underwent biopsy. The study, coordinated by the Department of Urology, University of Padova, Italy, shows that by using PSA-IgM and dedicated algorithms patients may be classified according to different PCa risk probabilities (iXip). Patients belonging to the very low risk group (iXip < 20%) should not be recommended for biopsy. In this group no patients with PCa are found and negative prostatic mappings may be reduced by 6.5 %. Patients belonging to the low risk group (iXip 20-30%) have a 3% probability of having PCa, so not recommending these patients for biopsy may lead up to a 24 % reduction in negative biopsies. Physicians according to their experience and patient's characteristics may not recommend a biopsy. For medium risk patients reduction of negative biopsies is more consistent (60 %) , but 17 % of patients may have PCa. Physicians according to their experience and patient's characteristics should evaluate to suggest a biopsy. For high and very high risk patients (iXip > 50%) biopsy should be recommended.