Somatostatin Receptor Imaging In Recurrent Medullary Thyroid Cancer

摘要

This study was performed to evaluate the clinical value of somatostatin receptor scintigraphy (SRS) in the diagnostic management of patients having recurrent medullary thyroid cancer (MTC).In 22 patients with recurrent MTC after primary surgical intervention, 33 SRS were performed. Planar imaging was carried after i.v. administration of 180 MBq of [111In]-DTPA-D-Phe1-octreotide (Octreoscan?), SPET of the neck and thoracic regions. The scintigraphical results were compared with the tumor markers human calcitonin (hCT), CEA, other imaging methods, histological findings, and clinical follow-up.In 36% (8/22) of the cases, SRS was concordant to the defined gold standard in the detection or exclusion of tumor tissue. If patients with liver metastases are excluded, SRS was positive in hCT levels >6.4 ng/ml and in hCT/CEA ratios >0.38.SRS can only be recommended to clear up equivocal findings especially in patients having sufficiently elevated titers of hCT levels and hCT/CEA ratios. Introduction Medullary thyroid carcinoma (MTC) originates in the calcitonin-secreting cells of the thyroid gland and represents 4-9% [1] of thyroid carcinomas. In 75% of the patients, the sporadic form of the disease can be observed whereas the remaining 25% have the hereditary form [2, 3]. Up to now, the genetic defects could be detected on the chromosome 10q11.2 [4].Human calcitonin (hCT) has been proven as the most reliable marker for primary, residual and recurrent medullary thyroid carcinoma [5, 6]. In this context, the pentagastrine-test is an important diagnostic tool.An exact determination of the tumor spread is mandatory because surgery is the only curative treatment modality with a five-year-survival rate of 70% [7], but only about a half of the patients will be primarily in remission after total thyroidectomy and neck dissection [8,9,10,11,12]. This is caused by the early nodal spread which is reported in 35 % of the patients [13, 14], the presence of distant metastases in 10-20% of the patients at the time of diagnosis, and the resistance to chemotherapy and radiotherapy [15].By autoradiographical methods the presence of positive somatostatin receptor staining has been reported in 40%-60% of primary medullary thyroid cancers [16]. Previously published sensitivities of in-vivo SRS are varying between 57% and 72% [17,18,19,20,21]. With regard to these differences and to the relatively high costs of SRS (comparing to CT and MRT) we want to report our results of SRS imaging in patients having recurrent MTC and compare those findings with other localization procedures, pathological and biochemical assessment. Patients and Methods Patients22 patients (8 female, 14 male, age 32-73 yrs. (mean: 51.3, SD: 12.1 yrs.) with suspicion of recurrent MTC after primary surgical intervention underwent 33 SRS examinations. 18 patients suffered from the sporadic and 4 from the hereditary form of the disease (Tab. 1). Because the extent of surgical intervention has influence on SRS findings, the collective of patients was divided into three groups: Group 1 (n=8):patients treated by thyroidectomy alone Group 2 (n=11):patients who received additional neck dissection Group 3 (n=3):patients treated as Group 2 with additional mediastinal resection of lymphatic metastases