[Studies on sensitivity test with clonogenic assay against chemo-endocrine therapy for human breast cancer]

The sensitivity of human breast cancer cells against estradiol-17 beta (E2), tamoxifen (TAM) and adriamycin (ADM) was investigated using the modified stem cell assay method by Hamburger and Salmon. Two hundred and six specimens, 145 from primary breast cancer and 61 from metastatic lesions, were placed in culture. Ninety eight specimens of them (47.1%) successfully formed more than 5 colonies per 5 X 10(5) cells plated. In 47 specimens (22.8%), more than 20 colonies were formed, which made it feasible to perform meaningful sensitivity test. Results obtained were as follows: Sensitivity against E2. More than 150% increase of colony formation was observed in the 36.7% cases of ER(+) group and in the 22.1% cases of ER(-) group. Sensitivity against TAM. When more than 60% inhibition in % colony formation was applied to cut off line, response rates for TAM were 21.7% in all cases, 26.7% in ER(+) group and 12.5% in ER(-) group, respectively. Sensitivity against ADM. When more than 50% inhibition in % colony formation was applied to cut off line, response rate for ADM was 26.7% in all cases. Higher response rate was observed in ER(-) group than in ER(+) group. Response rates of sensitivity test for TAM or ADM were very similar to the results obtained in the clinical use of TAM or ADM.