title: Expression of somatostatin receptor subtype 2 and subtype 5 in thyroid malignancies.
abstract: OBJECTIVE
  To retrospectively analyse the expression of somatostatin receptor subtypes 2 (SSTR 2) and 5 (SSTR 5) in thyroid malignancies, possibly the most relevant subtypes for targeted therapy with somatostatin peptide radioligands. In addition, findings were also correlated with the course of disease.
  
  
  METHODS
  87 consecutive patients (59 women, 28 men) with thyroid malignancy were included; 52 had papillary carcinoma, 24 follicular carcinoma, six medullary carcinoma, two poorly differentiated carcinoma and three anaplastic carcinoma. After initial therapy 70 (80.5%) patients showed complete remission, 11 (12.6%) patients partial remission with clinical and biochemical signs of residual disease and six (6.9%) patients progressive disease. The immunohistochemical staining results of the primary malignancy for SSTR 2 and SSTR 5 were semiquantitatively assessed and correlated with various outcome parameters.
  
  
  RESULTS
  In 10 of 87 (11.49%) thyroid cancer samples SSTR 2 showed positive immunohistochemical expression as compared to 75 of 87 (86.20%) for SSTR 5. All SSTR 2-positive cases expressed SSTR 5. Persistent or recurrent disease was found in 17 of 87 cases (19.54%). Fifty percent (6 /12) of SSTR 5-negative patients showed persistent disease as compared to 14.7 % (11 / 75) of SSTR 5-positive patients: seven of these were exclusively SSTR 5-positive, 4 showed dual expression of SSTR 5 and SSTR 2 (p = 0.01). No case showed only SSTR 2 expression.
  
  
  CONCLUSIONS
  SSTR 5 was shown to be the main receptor subtype in the analysed differentiated or anaplastic thyroid malignancies, whereas SSTR 2 was found only in a small percentage. Deficient SSTR expression may indicate higher risk for persistent or recurrent disease after initial therapy. For this reason immunohistochemistry can be considered a prognostic marker which should be further validated in prospective studies.
authors: S
authors: S
authors: Woelfl
authors: S
authors: S
authors: Bogner
authors: H
authors: H
authors: Huber
authors: S
authors: S
authors: Salaheddin-Nassr
authors: M
authors: M
authors: Hatzl
authors: C
authors: C
authors: Decristoforo
authors: I
authors: I
authors: Virgolini
authors: Prof. Dr. Michael Gabriel, Department of Nuclear Medicine and Endocrinology General Hospital, Krankenhausstr. 9, 4021 Linz, Austria, Tel. +43/(0)732/78 06 61-41, Fax -65, E-mail: michael.gabriel@akh.linz.at, michael.gabriel@i-med.ac.at.
authors: M
authors: M
authors: Gabriel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D017481:Receptors, Somatostatin / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000628:therapy*; D014018:Tissue Distribution; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D017481:Receptors, Somatostatin; C574734:SSTR2 protein, human; C094573:somatostatin receptor 5
keywords: Somatostatin receptor expression; immunohistochemistry; prognostic marker; thyroid carcinoma