Growth of human colorectal carcinoma implants in the mouse subrenal capsule assay

The subrenal capsule assay (SRCA) in normal immunocompetent mice was performed from 1331 implants of 43 human colorectal carcinomas to evaluate the possible applications for clinical chemosensitivity testing. Also the effect of an immunosuppressive agent, cyclosporine, was tested on the growth of tumours. Histologically in all except one of 23 saline-treated tumours the original tumour tissue was replaced by granulation tissue and inflammatory cells. This was also true in cyclosporine-treated mice since in only one of the nine tests tumour cells were observed. The macroscopic growth of the implants in the cyclosporine-treated mice was significantly less than in the saline-treated mice. Flow cytometric DNA-analysis revealed that the difference between macroscopic growth of saline and cyclosporine-treated groups was observed only in DNA-diploid tumours. We conclude that new methods are required to preserve the viability of human colorectal carcinoma in the SRCA.