the present disclosure provides methods for the diagnosis of metastatic prostate cancer and / or the prediction of the metastatic ability of prostate cancer in prostate biopsy tissue . metastatic ability of prostate cancer is positively correlated with the level of transcriptional and translational expression of the muc18 coding sequence in the neoplastic tissue . methods for the determination of muc18 protein synthesis include western blots , elisa , radioimmunoassay , immunofluorescence , and other immunoassays using muc18 - specific antibody and suitable detection means . methods for measurement of transcriptional expression of the muc18 coding sequence include northern hybridizations and quantitative reverse transcriptase - polymerase chain reaction analyses . absence of or very low muc18 expression in the prostate tumor tissue is associated with nonmetastatic cancer , while relatively high levels of muc18 expression are predictive of prostate cancer which is likely to metastasize or which has already metastasized . the present disclosure provides an improved diagnostic tool to aid the medical community in the choice of appropriate treatment regimens for prostate cancer patients .