Localization of radioactive lead in ocular and skin melanoma.

The ability of radioactive lead to localize melanomas was studied. The Greene melanoma in the Syrian Golden hamster served as a model for both skin and ocular melanoma. The affinity of heavy metals for neoplasms has been studied but previous reports have been inconsistent as to tumor specificity. For this investigation the radioactive lead (203-Pb,) was studied as the chemical complex 203-Pb-Tris. Significant tumor:nontumor ratios were found in ocular melanoma and the concentration in the lens was minimal. The ratio of per cent uptake per gram of tumor: per cent uptake per gram in control tissue with skin melanoma was 9.4 at 24 hours and for the eye melanoma the ratio was 26.3 at 24 hours. The affinity of 203-Pb-Tris for melanomas appears to be as promising as other compounds presently being evaluated for ocular scintigraphy, namely, labeled quinoline analogs. Therefore, further preclinical evaluation is warranted.