IN-VIVO INACCESSIBILITY OF SOMATOSTATIN RECEPTORS TO IN-111-PENTREOTIDE IN PRIMARY RENAL-CELL CARCINOMA

The presence of somatostatin receptors on human renal cell carcinomas in surgically removed kidneys has been demonstrated by autoradiography . The aim of this study was to detect the in vivo presence of somatost atin receptors in primary renal tumours and their possible metastases before surgery, using In-111-pentreotide scintigraphy. Tl-201 was used as a sensitive tumour-seeking agent with blood flow-dependent uptake. Fifteen patients were imaged before surgical removal of the renal tum our. Thirteen tumours were malignant. The large tumours (more than 4 c m in diameter) did not accumulate In-111-pentreotide or Tl-201. In con trast, the single small tumour accumulated both tracers. A scalp skin metastasis was demonstrated in one patient by Tl-201 and In-111-pentre otide uptake. In one case, known lung metastases were visualized with both Tl-201 and In-111-pentreotide, but the lung metastases of another three patients as well as one case of epidural metastasis were not id entified. In one patient with a photopaenic lesion, positive labelling of the surgically removed tumour was demonstrated by in vitro autorad iography. Somatostatin receptor scintigraphy with In-111-pentreotide a ppears to have Little value for the detection of metastases in patient s with renal cell carcinoma, as some metastases (especially those of t he lungs) were missed. The absence of In-111-pentreotide uptake by lar ge primary tumours is an interesting finding, suggesting inaccessibili ty of these very large tumours to drugs. ((C) 1998 Lippincott Williams & Wilkins).