Cell Kinetics of Renal Cell Carcinoma Studied with in Vivo Iododeoxyuridine Incorporation and Flow Cytometry

In 29 patients with renal cell carcinoma tumor cell kinetics were studied by in vivo labeling with 100 mg. iododeoxyuridine given 3 to 7 hours before nephrectomy. Two to 6 samples were analyzed from each tumor after fixation in ethanol. Iododeoxyuridine was analyzed by specific antibodies using flow cytometric analysis of labeled cells and parameters, such as labeling index and potential tumor doubling time, could be determined. Samples from 28 tumors were evaluable. Mean labeling index of the tumors was 2.7%, which was significantly different from the 0.35% index in kidney cortex tissue. There was no statistical difference in labeling index among the clinical stages. The mean potential tumor doubling time in the tumor cells was 20.3 days, which was significantly different compared with 137.7 days in kidney cortex tissue. There was a frequent intra-tumoral heterogeneity of potential tumor doubling times. Diploid and aneuploid samples had significantly different potential tumor doubling (mean 37.4 and 12.5 days, respectively). Potential tumor doubling had a significant impact on the survival time (p = 0.004), which also was noted in the patients with aneuploid tumors (p = 0.003). Our study shows that in vivo incorporation of iododeoxyuridine successfully can be analyzed in renal cell carcinoma. Potential tumor doubling time gives valuable prognostic information on the clinical behavior of the patients.