Affinity of Lanthanons for Malignant Tumor (II)

Abstract

Affinity of¹⁶⁹Yb and¹⁷⁰Tmfor the malignant tumor was examined. Citrates or chlorides of these elements were prepared and injected intravenously to the rats which had subcutaneously transplanted Yoshida sarcoma and these rats were sacrificed 3 hours, 24 hours and 48 hours after injection. The radioactivities of the tumor, blood, muscle, liver, kidneys and spleen were measured by a well type scintillation counter.
The retention values in these organs were calculated and expressed as a percent dose per gram-tissue weight. The retention values of¹⁶⁹Yb, ¹⁷⁰Tmin tumor were 0.7% /g-1.1%/g (to administered dose) and these values were similar to that of gallium. At 24 hours after injection, tumor-muscle concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere 24-52, tumor-blood concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere 43-57, tumor-bone concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere 0.4-0.3. Values of tumor-muscle and tumor-blood concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere far superior to that of⁶⁷Ga, but values of tumor-bone concentration ratio of¹⁶⁹Yband¹⁷⁰Tm were inferior to that of⁶⁷Ga.Tumorliver concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere larger than that of⁶⁷Ga, but tumorkidney concentration ratio of¹⁶⁹Yband¹⁷⁰Tmwere smaller than that of⁶⁷Ga.In our experiments using croton oil-induced inflammation in the rats, ¹⁶⁹Ybalso had strong affinity for inflammation.
The chemical form of¹⁶⁹Yband¹⁷⁰Tmsuitable for the selective uptake by tumor cells should be carrier free or having a little carrier and able to produce the ions of these elements easily in the body.¹⁶⁹Yband¹⁷⁰Tmwere similar to⁶⁷Gain affinity for the malignant tumor and various organs, but these two elements were more rapidly taken up in the bone from blood than⁶⁷Ga.