Human lung tumors: SPECT quantitation of differences in Co-57 bleomycin uptake

A newly developed single photon emission computed tomography (SPECT) method was used to measure noninvasively the concentration of labeled drugs in human lung tumors. The validity of the method was established by the high correlation (r = .92) between in vivo SPECT measurement of the concentration of glucoheptonate labeled with technetium-99m and in vitro measurement of the concentration of the drug in specimens of nine of the same tumors obtained at surgery. The in vivo concentration of intravenously injected bleomycin labeled with cobalt-57 was measured over time in 14 human lung tumors. Significant differences were found in the uptake of bleomycin by the tumors, even those with the same histologic characteristics, when the concentration over time, the tumor/blood ratio at 30 minutes, and the tumor cumulative concentration were measured in vivo. Since the drug concentration in the blood was not related to the concentration in the tumor (r = .54), uptake of chemotherapeutic drugs should be measured in each patient individually.