Carcinoma of the colon and rectum: Circulating malignant cells and five‐year survival

Circulating malignant cells are found infrequently in the peripheral blood of patients with carcinoma of the colon and rectum. The incidence rises on induction of anesthesia (28%), and tumor cells can be identified in the peripheral blood of 50% of patients during surgery. Some of the important features in their cytologic identification (and distinction from other large mononu-clear cells) are reported. There is a 57% yield when the blood sample is taken from the inferior mesenteric vein draining the tumor in the rectum or left colon. Five-year follow-up on two series of 50 patients shows that the detection of circulating malignant cells has no prognostic significance, and it is not related to the presence of histologic evidence of venous invasion, although this invasion itself is associated with a worse outlook. Fifty-six per cent of patients in whom circulating tumor cells were found at surgery are alive and well without sign of recurrence or metastasis. In cases where blood samples were taken from the common or internal iliac vein before and after ligation of the inferior mesenteric vein, it was noted that patients with no detectable circulating tumor cells had a tendency towards liver metastases, whereas those showing circulating cells in pelvic veins, only after mesenteric vein ligation, had a tendency towards systemic bony deposits. During the isolated perfusion of excised tumors, it was found that addition of a fibrinolytic agent caused the liberation of large numbers of cells. Naturally occurring fibrinolysis may play a part in the liberation of cells into the bloodstream and in their subsequent ability to establish metastases.