EFFECTS OF METASTATIC AND NONMETASTATIC MAMMARY ADENOCARCINOMA ON TISSUE DISTRIBUTION OF GA-67 IN THE RAT

The purpose of this work was to study the effect of metastatic and non-metastatic mammary adenocarcinoma on tissue distribution of gallium-67 (Ga-67) citrate in Fischer-344 female rats by the use of gamma counting techniques. The homogenate (0.1 mm) of a sample of metastatic and non-metastatic tumor was implanted by subcutaneous injection in the right footpad of each animal's hind extremity. The animals bearing metastatic tumor were studied 2-24 days and the non-metastatic group 2-30 days after the implantation of tumor homogenate. The control group consisted of four animals and tumor-bearing groups of seven to eight animals at each time point. All animals were injected with 1.11 MBq of Ga-67 citrate by intravenous administration and sacrificed in halothane anesthesia 48 h later. The relative tissue uptake data are presented as arithmetical mean value with a standard error and graphically demonstrated as normalized data with respect to control. The results demonstrate that Ga-67 citrate uptake was largely unaffected in most organs by the presence of either metastatic or non-metastatic tumor. Gallium-67 uptake, however, was significantly and consistently increased in the popliteal lymph nodes of the ipsilateral extremity of tumor implant in the metastatic group. No difference was observed in the non-metastatic tumor group. The findings of this experimental work indicate that the host reaction to the tumor does not modify the gallium uptake characteristics in the normal tissues of tumor-bearing animals.