Radioactive phosphorus uptake test. An in vitro analysis of choroidal melanoma and ocular tissues

The concentration of radioactive phosphorus in uveal melanoma and normal parts of the eye was determined in vitro in 14 eyes. The eyes were enucleated after a positive 32P uptake test. Portions of the melanoma as well as normal choroid, retina, sclera, lens, and vitreous were analyzed. The 32P uptake test had been performed at various intervals after intravenous administration of 32P from 24 to 556 hr. The in vitro uptake of 32P was compared to cell type, tumor volume, time of testing, percent uptake measured clinically, and specific activity. The only positive correlation was between percent uptake measured clinically and 32P concentration (dpm/gm). A higher concentration of phosphorus in melanoma resulted when carrier-free 32P was used. A negative correlation existed between number of hours from injection to clinical measurement of percent uptake, although melanoma to normal choroid ratios did not change from 24 to 72 hr. No correlation was found between uptake and tumor volume. The sample was small; however, we saw no correlation between 32P uptake and degree of malignancy.