Clinical Significance of Cancer Cells in the Circulating Blood

Lung colony formation: A selective cloning process for lung-colony-forming ability

“…This indicates that some factors responsible for lungcolony formation are different from those involved in local subcutaneous growth. The present experimental results agree with various clinical and experimental facts: the inefficiency of metastasis formation despite the presence of many malignant cells in the blood stream (Engel, 1959;Roberts et al, 1961) tumour-specific distribution of metastatic foci, the "seed soil theory" of Paget (1889), and the development concept of malignancy which suggests heterogeneity of karyotype or malignant characteristics among cells in a tumour (Makino, 1957;Foulds, 1969;Nowell, 1976). Fidler (1973) has already isolated highly metastatic variants of B16 melanoma cells by 5 to 10 passages of the cells as lung metastases.…”

“…Both tumour-cell and host factors could be involved and interact in all these steps (Zeidman, 1957;Rubin & Green, 1968;Thompson, 1976). Metastatic foci are formed at low frequency in spite of the release of many malignant cells into the circulation (Engel, 1959;Roberts et al, 1961) or despite i.v. injection of many living cells (Iwasaki, 1915; Takahashi, 1915;Warren & Davis, 1934.)…”

Prognostic significance of CEA levels and detection of CEA mRNA in draining venous blood in patients with colorectal cancer

“…If some circulating tumor cells result in metastases, their detection might be valuable in patients' prognosis. Detection of tumor cells in blood from colorectal cancer patients traditionally has been performed by cytology or immunochemistry using anti-cytokeratin antibodies [4][5][6][7][8]. With recent advances in molecular techniques, many investigators have succeeded in detecting circulating tumor cells with high sensitivity by using reverse transcriptase-polymerase reaction (RT-PCR) targeting either carcinoembryonic antigen (CEA) or any of a number of cytokeratin (CK) isozymes [9,10].…”

Circulating Tumor Cells and Colorectal Cancer

“…This idea regained attention almost a century later when Engell [4] found evidence of CTCs in live cancer patients. However, follow-up studies by Engell [5] and others [6] found no correlation between survival and the number of tumor cells in the blood, likely because of poor cytologic criterion largely founded on cell morphology and size. Technological advances in subsequent years have increased the ability to accurately and reliably detect CTCs.…”