[Somatostatin receptor status in non-medullary thyroid carcinoma]

Recent in-vitro and in-vivo studies demonstrated a somatostatin receptor expression in some non-medullary thyroid carcinomas. In this study we investigated the somatostatin receptor status for this particular tumor entity in a larger patient group.

We compared 131-iodine with 111-In-pentetreotide scans in 24 patients with metastasizing, non-medullary thyroid cancer. The findings were correlated with other imaging modalities. Additionally, we performed receptor autoradiography in one patient, octreotide therapy in another patient and administration of 90-Y- and 111-In-DOTATOC in 2 consecutive patients.

In the 15 patients with papillary or follicular carcinoma, 111-In-pentetreotide was inferior to 131-I in 8/15, equal in 1/15, and superior in 6/15 patients. In 8/9 of the patients with Hürthle cell carcinoma, metastases showed a 111-In-pentetreotide accumulation of various intensity, while 131-iodine scans were negative except for one patient. 111-In-pentetreotide was equal or superior compared to 201-Tl or 99m-Tc-sestamibi, but for the most part inferior in comparison with 18-F-FDG-PET. The findings of 111-In-pentetreotide scintigraphy correlated well with the receptor autoradiography and the accumulation of DOTATOC, but not with the therapeutic effect of "cold" octreotide on the thyroid cancer metastases.

Several metastases of papillary and follicular carcinoma, and the majority of Hürthle cell cancer metastases can express somatostatin receptors. 111-In-pentetreotide scintigraphy is a promising tool for localization of metastases especially in Hürthle cell cancer or if PET is not available, and may be useful for selection of possible candidates, if therapeutic effective beta-emitting somatostatin analogues will be available for routine application.