Cell kinetic measurements in prostate cancer

Two approaches have been suggested for escalating the total dose in radiotherapy treatment of prostate cancer. One is conformal radiotherapy; the other is hyperfractionation using many small fractions. Both imply some possible prolongation in overall treatment time. To judge whether prolonged treatment schedules would be detrimental, it is necessary to know the proliferation rates in human prostate tumors, specifically, the potential doubling time (Tpot). There is a lack of data on this parameter in the literature. Seven patients with adenocarcinoma of the prostate were studied. A tracer dose of 100 mg/m2 of IUdR was infused intravenously 4-12 h before biopies were taken. Biopsies were fixed in 70% ethanol, stored at 4 degrees C, and later prepared and stained by standard methods for flow cytometry, using the red fluorescence signal for DNA and the green fluorescence signal (fluorescein isothiocyanate) for 5-iodo-2'-deoxyuridine. The duration of DNA synthesis (Ts) was determined by the relative movement (RM) method, knowing the interval between tracer administration and biopsy. Tpot was calculated as the quotient of Ts by labeling index (LI). In two of the seven tumors the LI was too low (