The present invention relates to the design of three novel monoclonal uPAR sandwich assays for the specific detection of 1) full-length intact uPAR, 2) full-length intact uPAR and domain 2+3 fragment, and 3) domain 1 fragment of uPAR. The invention further relates to a method combining the detected amounts of uPAR forms in a sample with data indicative of the presence of the cancer disease. The method can be used for staging, prognosis or diagnosis of prostate cancer. Two novel monoclonal antibodies and a kit and immunoassays for detecting at least one uPAR form(s) are also described in the present invention.