On twenty-three specimens from patients with
osteosarcoma (biopsied tissue, resected specimens from primary and metastatic lesions), the human
tumor clonogenic assay (
HTCA: standard assay) as well as cultivated
HTCA involving short-term cultivation of a single-cell
suspension, was carried out. The percentage colony-forming ability, which was very small for standard
HTCA, increased significantly when cultivated
HTCA was performed. With cultivated
HTCA, sensitivity tests were possible in 87% of the specimens, in contrast to only 28.6% with standard
HTCA. Retrospective evaluation of the results obtained by cultivated
HTCA with the clinical efficacy of anticancer drugs showed a true positive rate, 66.7%, and a true negative rate, 88.9%. This analysis revealed that drugs shown to be ineffective and that
tumor cells are refractory to those drugs, so that clinical use of such drugs should be avoided.