The prognostic impact of cytokeratin‐positive cells in bone marrow of patients with localized prostate cancer

Abstract

Our study evaluates the prognostic significance of the cytokeratin‐positive mononuclear cells (CK+ cells) in the bone marrow (BM) and peripheral blood (PB) as detected by immunocytochemistry in patients with locoregionally confined prostate cancer. BM and PB samples were obtained from 66 newly diagnosed patients with T1‐4pN0M0 prostate cancer. All samples were analyzed by standardized immunocytochemical methods (anticytokeratin mononuclear antibody; AE1/AE3) applying a negative immunomagnetic cell enrichment technique. A second sampling was obtained in 60 of the 66 patients ≥2 years after definitive radiotherapy. The median follow‐up after high‐dose radiotherapy of the patients was 65 months. For the analysis of the postradiotherapy clinical progression‐free survival (PFS) treatment, failure was defined as pelvic tumor growth or development of distant metastases. At diagnosis CK+ cells were found in BM in 14 of 66 (21%) prostate cancer patients. This was not associated with an increased risk of progression. On the other hand, the presence of CK+ cells in 12 of 60 (20%) patients at the second BM aspiration was significantly related to a shorterPFS (p = 0.02). In the multivariate analysis, the presence of CK+ cells in the posttreatment BM did not remain as an independent variable of PFS assessment if posttreatment PSA was entered into the analysis. CK+ cells in PB were found in 12% of the patients. After therapy, none of the patients had detectable CK+ cells in PB. The presence of CK+ cells in the posttreatment but not in the pretreatment BM was associated with decreased PFS in patients irradiated for pelvis‐confined nonmetastatic prostate cancer. Although this association was not retained in multivariate analysis, our observations indicate that the presence of CK+ cells after local therapy define a group of patients that have a high risk of developing distant metastases.