Quantitative study on the liberation of tumor cells into the circulating blood

A study was undertaken to investigate the mechanism of liberation of tumor cells into the blood stream in connection with the process of tumor growth, using three strains of ascites tumor such as Yoshida sarcoma (YS) with infiltrative growth pattern, AH100B with expansive one, and AH109A with intermediate one. For this experiment, a new method for the quantitation of the number of circulating tumor cells was devised. From its results, it was concluded as follows: (1) Tumor cells appear first in the circulating blood at the transitional phase from logarithmic growth to declining growth. (2) Tumor size is a macroscopical index of the risk of the liberation of tumor cells into the blood stream. (3) Tumor necrosis is a histological sign suggesting that the tumor growth phase is declining, namely, that hematogenous dissemination of tumor cells has begun already. (4) There is a striking difference in the frequency and number of tumor cells in the venous blood among these three tumor strains. The tumour strains in order of the number of the circulating tumor cells are YS, AH109A, and AH100B. (5) In YS and AH109A, the transition of the number of tumor cells liberated into the blood stream is closely related to the growth process of tumor tissue. (6) Liberated cells of AH109A and AH100B disappear promptly from the blood stream.