The growth and metastasis of four commonly used tumour lines implanted into eight different sites: evidence for site and tumour effects.

The growth and metastasis of four commonly used experimental tumour lines have been compared after the implantation of cells into a lobe of the liver, the spleen, the left kidney, the peritoneal cavity, the thorax, the right thigh muscle, subcutaneously into the dorsolumbar region and intravenously into the tail vein or the right femoral vein. This was done to assess the importance of site in affecting metastatic distribution, and to determine whether any general conclusions could be drawn as to the role of this factor. Tumours grew at variable rates in different sites, but this did not affect the extent or distribution of metastasis. Each line gave a characteristic pattern that could be considerably modified by site. For example, in the spleen, metastasis was always extensively to the liver; in the kidney, and to some extent in the muscle, metastasis was similar to that obtained for intravenously injected cells; in the peritoneal cavity or thorax, metastasis was usually lower than from other sites; and in the liver, the metastasis to other lobes of the liver and to the lungs was modified. Many of these findings could be explained by both specific and non-specific factors operating at each site. It is suggested that interactions at the primary site of tumour growth may be very important in affecting metastasis, and that in the future more attention should be given to this factor in order to make progress in understanding tumour spread.