Uptake of [131I]thiouracil in tumours of patients with disseminated malignant melanoma. A pilot study.
Previous studies on mice carrying melanoma have shown that 5-iodo-2-thiouracil (ITU) is accumulated in the tumours due to its specific incorporation into melanin during its synthesis. ITU is also selectively localized in murine melanoma metastases and in cultured human melanoma cells. Progressive formation of melanin is, however, a prerequisite for the incorporation. Four patients with disseminated melanoma were injected intravenously with 39-62 MBq [131I]TU. Blood and urine samples were gradually collected, and 3-7 days postinjection tumours were biopsied and examined by impulse counting. The patients were scanned with a gamma camera over the total body daily for 3-4 days. The radioactivity was rapidly excreted. Poor melanin pigmentation of the tumours and low proliferation rate (possibly induced by chemotherapy) decreased the uptake of radioactivity by the tumors, and no imaging was possible. One of the patients, however, had clearly progressive disease with darkly pigmented metastases which contained considerably higher levels of radioactivity than the surrounding skin. Calculations indicated that a doubling of the radioiodine dose would probably make visualization of the tumours possible.
Olander
K
K
Department of Toxicology, Uppsala University, Sweden.
Larsson
B S
BS
Ringborg
U
U
Schnell
P O
PO
D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008543:Melanins / Q000032:analysis; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000556:secondary; D011877:Radionuclide Imaging; D012878:Skin Neoplasms / Q000000981:diagnostic imaging*; D013889:Thiouracil / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014018:Tissue Distribution
D007457:Iodine Radioisotopes; D008543:Melanins; D013889:Thiouracil; C036667:iodothiouracil