In summary, the ATCCS is an efficient culture system which grows clonogenic cells from greater than 80% of human cancers. The ATCCS supports the growth of malignant cells from human cancers. The ATCCS shows classical drug and radiation survival curves which routinely achieve over 1 log of kill. The ATCCS has high CFE and permits sensitivity testing from small samples. Clinical correlations for the chemosensitivity assay were satisfactory. Radiosensitivity in vitro correlates with tumor histology.