The invasion of veins by many malignant tumors has been shown by numerous investigators,1-4 but reports of the actual cytologic demonstration of cancer cells in the circulating blood have been relatively few,5,6 due to the technical difficulty in the separation and identification of the few cancer cells from the numerous formed elements of the blood. This study is a continuation of work begun four years ago7 and concerns the technique for the isolation of cancer cells from the blood and the occurrence of these cancer cells in the circulating blood, including the changes wrought by the manipulation incident to surgery.
Demonstration of Cancer Cells in Venous Blood.
—In 1869, Ashworth8 found cells in the blood which were of the same size and appearance as those of the patient's multiple malignant skin tumors. Schleip,9 in 1906, described cells varying from the normal in a