Haematogenous dissemination of cells from human renal adenocarcinomas

Estimates were made of the rates at which cancer cells were released directly into the renal vein in patients undergoing radical nephrectomy for primary renal cancer. Cancer cells were counted in blood samples taken from the renal vein using a density gradient centrifugation procedure, and identified using immunocytochemical techniques, on the basis of their cytoskeletal intermediate filament proteins. Cancer cells were released as single cells and multicell emboli in 8/10 patients, in numbers varying widely between 14-7509 emboli ml-1 of blood. Despite a calculated median input into the metastatic process of 3.7 x 10(7) cancer cells per day for at least 180 days, only 3/10 patients had extraperitoneal metastases prior to surgery and only 1 of the remaining disease-free patients subsequently developed distant metastases over a maximum 35 month period. These results are discussed in terms of primary tumour kinetics and metastatic inefficiency.