Detection of disseminated tumour cells in blood and bone marrow samples of patients undergoing hepatic resection for metastasis of colorectal cancer.

BACKGROUND: In 50-60 per cent of patients who undergo hepatic resection for metastasis of colorectal cancer the first site of tumour recurrence is extrahepatic, indicating the presence of more extensive disease at the time of resection. The aim of this study was to evaluate whether the presence of disseminated tumour cells in blood and bone marrow could predict extrahepatic tumour recurrence. METHODS: Cytokeratin 20 (CK20) reverse transcriptase-polymerase chain reaction was used to study the presence of tumour cells in preoperative peripheral blood and bone marrow samples from 41 patients with liver metastasis scheduled for surgical resection. RESULTS: CK20 expression was detected in six of 41 peripheral blood samples and in eight of 32 bone marrow samples. There was no correlation between CK20-positive samples and subsequent extrahepatic recurrence. Positive blood samples did, however, correlate with high serum carcinoembryonic antigen level and large tumour volume. None of the 14 patients previously treated with chemotherapy had CK20-positive samples, whereas six of 27 blood and eight of 20 bone marrow samples were positive in the chemotherapy-naive group. CONCLUSION: Although the number of patients in this study is limited, the presence of disseminated tumour cells did not predict subsequent extrahepatic recurrence. The results strongly suggest that the presence of circulating tumour cells in peripheral blood may reflect transient shedding of tumour cells related to large tumour volume.

Investigations for a multi-marker RT-PCR to improve sensitivity of disseminated tumor cell detection.

BACKGROUND: In order to develop a multi-marker RT-PCR, which as such may be more sensitive than a single marker assay for the detection of disseminated tumor cells, we evaluated six RT-PCR markers: cytokeratin 20 (CK20), carcinoembryonic antigen (CEA), guanylyl cyclase C (GCC), epidermal growth factor receptor (EGFR), matrilysin (MMP-7) and HeLa metastatic gene (HLM). MATERIALS AND METHODS: The expression was studied in human colon tumor cell lines, in colon cancer tissues, and in blood and/or bone marrow samples of colorectal cancer patients and control subjects. RESULTS: The cell lines showed a differential expression pattern. The expression of all markers was detected in control blood samples with the lowest frequency for CK20 and EGFR. Semiquantitative analysis, which was performed to study threshold setting, demonstrated that GCC expression was elevated in patient compared to control samples. However, the reproducibility was questionable. CONCLUSION: The results presented in this study suggest an enhanced sensitivity for a combination of RT-PCR markers. Due to limited specificity however, the development of a multi-marker RT-PCR by using conventional PCR does not seem feasible. Future studies should focus on the potential of quantitative RT-PCR.

Limitations of cytokeratin 20 RT-PCR to detect disseminated tumour cells in blood and bone marrow of patients with colorectal cancer: expression in controls and downregulation in tumour tissue.

AIMS: Despite informative staging of patients with colorectal cancer, some patients with localised disease at diagnosis will develop recurrence or metastasis. Attempts to improve staging include sensitive detection of disseminated tumour cells in blood and bone marrow by reverse transcriptase polymerase chain reaction (RT-PCR). The results of this study have been considered in relation to the controversial results in the literature to elucidate the usefulness of cytokeratin 20 (CK20) RT-PCR to detect disseminated tumour cells further. PATIENTS/METHODS: Blood and bone marrow samples from 30 patients with colorectal cancer were studied by CK20 RT-PCR. Specificity was evaluated in 47 blood and 15 bone marrow samples from non-cancer controls. In addition, the expression of CK20 mRNA and protein was studied in normal and tumour colon tissue samples. RESULTS: CK20 expression was detected in nine of 30 and nine of 19 of the blood and bone marrow samples from patients with colorectal cancer, respectively. In non-cancer control blood and bone marrow samples, CK20 expression was detected in 10 of 47 and four of 15, respectively. A difference between patient and control samples may be observed in terms of frequency of positive PCR tests. In tissue samples, CK20 mRNA expression was downregulated in tumour compared with normal colon tissue. CONCLUSIONS: CK20 expression was downregulated in tumour tissue compared with normal colon and a background expression of CK20 was seen in some control blood and bone marrow samples. Despite a lack of standardisation (which hampers comparison of studies), these results, together with other reports in the literature, suggest that CK20 may still be a suitable marker, but that background expression and threshold setting should be studied further.