Arrest of Circulating Tumor Cells Versus Metastases Formation

Abstract

THERE have been numerous reports in recent years on the findings of cancer cells in the peripheral blood of patients with malignancy.^1-3 It was suggested that the presence of these cells reflected the biological activity of the tumor and portended a limited prognosis.⁴ Follow-up studies, however, have failed to confirm this initial supposition and the estimated prognostic value of circulating tumor cells has been substantially reduced.^5,6 Reexamination of the slide material would probably reduce the percentage of positive findings originally reported.⁷ Furthermore the disappearance rate of such cells from the blood as has been demonstrated in animal studies is very rapid.^8,9 This would tend to reduce the importance of finding tumor cells in any given blood sample since the positive sample would reflect more a fortuitous time sequence than a steady clinical state of malignant cytemia. Undoubtedly most circulating tumor cells are rapidly arrested but