POTENTIAL OF THE HISTOCULTURE DRUG-RESPONSE ASSAY TO CONTRIBUTE TO CANCER-PATIENT SURVIVAL

The histoculture drug-response assay (HDRA) was recently evaluated in a retrospective clinical trial and was found to correlate to drug sens itivity, resistance, and patient survival, To further investigate the potential of HDRA to contribute to patient survival, 215 patients with gastric cancer from 45 medical centers were tested with the HDRA in a blinded study after resection of the primary lesion, One hundred sixt y-eight patients received at least 20 mg/m(2) of mitomycin C and a min imum of 30 g UFT, a mixture of tegafur and uracil at a molar ratio of 1:4, thereby making them eligible for the study, Of these cases 128 we re evaluable by the HDRA, The evaluable patient tumors were tested by the HDRA with the [H-3]thymidine incorporation end point measured by m icroautoradiography to be drug ''sensitive'' or ''resistant,'' The in vitro conditions for distinguishing sensitivity and resistance that ma tched the response rates for historical controls for gastric carcinoma were 90% inhibition rate and 0.12 mu g/ml for mitomycin C and 70% inh ibition rate and 1 mu g/ml for 5-fluorouracil, respectively, Most impo rtantly in the blinded study, the overall and disease-free survival ra tes of the HDRA-sensitive group were found to be significantly higher than those of the HDRA-resistant group tested under the above conditio ns, The data further indicate the importance of three-dimensional tumo r culture for obtaining accurate clinical information, The results dem onstrate that the HDRA response correlates to patient survival, which suggests the potential of the HDRA to contribute to patient survival i n gastric cancer when used prospectively.