Circulating cytokeratin-positive cells and tumor budding in colorectal cancer

Aim: To investigate whether circulating cytokeratin-positive (CK⁺) cells in the mesenteric blood of resected colorectal specimens are prognostic and correlate with tumor budding.

Methods: Fifty-six colorectal specimens were collected between 9/2007 and 7/2008. Blood from the mesenteric vein was drawn immediately after receiving the fresh and unfixed specimens in the pathology department. After separation of the mononuclear cells by Ficoll-Hypaque density-gradient centrifugation, cytological smears were immunocytochemically stained for CK18. Tumor budding was evaluated on slides stained for pan-cytokeratin. The identification of ≥ 30 buds/1.3 mm² was defined as high grade budding.

Results: CK⁺ cells and clusters were identified in 29 (48%) and 14 (25%) of the samples, respectively. Two cells were identified in one of three non-malignant cases. Clusters were found exclusively in malignant cases. The occurrence of CK⁺ cells or clusters was not associated with any of the evaluated clinicopathological factors, including surgical technique and tumor budding. Moreover, the occurrence of CK⁺ cells or clusters had no influence on the cancer-specific survival [75 mo (CI: 61; 88) vs 83 mo (CI: 72; 95) and 80 mo (CI: 63; 98) vs 79 mo (CI: 69; 89), respectively].

Conclusion: CK⁺ cells and showed neither prognostic significance nor an association with tumor budding. It is very likely that CK18-staining is not specific enough to identify the relevant cells.