Background: The aim of this study was to prove the reliability of cytokeratin 18/prostate specific antigen (CK18/PSA) immunocytochemistry to detect tumor cells in the bone marrow of patients with prostate cancer (CaP) compared with a control group without CaP.
Patients and methods: In bone marrow aspirates of 34 patients with CaP and 11 control patients without CaP, CK18/PSA immunocytochemistry was performed and compared with PSA RT-PCR in bone marrow and blood.
Results: 12% of tumors showed a positive staining with PSA and and 17% with CK 18 immunocytochemistry. There was no correlation with the stage or grade of the CaP. False positive results occurred in 2 out of 6 males without CaP and in 2 out of 5 women. 35% of the samples were found to have PSA-mRNA signals in RT-PCR which were neither associated with the histological stage or grade nor the PSA staining in immunocytochemistry.
Conclusion: False positive staining results were obtained in control patients. Detection of PSA-mRNA was not associated with immunocytochemistry. Neither immunocytochemical nor PCR results were associated with the histological stage of the CaP. Thus, detection of micrometastasis using immunocytochemical methods has to be interpreted with caution and cannot be recommended as a clinical staging procedure.