[Colony formation of solid tumors in in vitro colony assay (human tumor stem cell assay)]

Colony forming ability of solid tumor cells was studied in a tumor colony assay (human tumor stem cell assay). In 50 cases of solid tumors, cloning efficiencies of 5 X 10(5) cells plated were as follows: breast cancer 12/12 (100%), colon cancer 10/11 (91%), ovarian cancer 9/9 (100%), sarcomas 7/9 (78%), gastric cancer 3/6 (50%), endometrial cancer 2/2 and pancreatic cancer 1/1. An overall cloning efficiency was 88% (44/50) and this rate is higher than those reported in literatures. Ovarian cancer showed the highest plating efficiency of 0.07% (number of colonies/number of cells plated X 100%) in various solid tumors tested. Subsequently, plating efficiencies of colon and breast cancer were 0.03 and 0.01%, respectively. In the cases of sarcomas and gastric cancer, low plating efficiencies were seen (0.008%, 0.003%). The overall rate succeeded colony growth of solid tumors was somewhat higher in enzymatically treated tumor cells, that is, cloning efficiencies in mechanical and enzymatic methods were 85 and 90%, respectively. The enzymatic disaggregation is an advantageous method in gastric cancer and sarcomas. Various solid tumors can be formed colonies in soft agar and chemosensitivity test using in vitro colony assay is expected in solid tumors.