Initial observations and problems with in vitro predictive assay in genitourinary malignancies

Recently, techniques have been developed that allow in vitro growth and chemotherapy sensitivity testing of human malignancies. We report our initial experience with the clonogenic, or colony-forming, assay as applied to genitourinary malignancies. Over the past two years, 172 specimens of genitourinary tumors were sent for assay. Thirty-three per cent were not plated, either because of sufficient quantity of cells obtained in the sample or because of the low viability percentage as determined by trypan blue exclusion. Forty-seven per cent showed adequate growth for chemosensitivity testing whereas 20 per cent of the samples showed inadequate growth. A major problem was obtaining adequate numbers of viable cells. Several other problems make it difficult to draw clinical correlations from in vitro findings. The method appears promising for several potential applications, but further studies will be needed before the final utility of the methods is defined.