Relation of 18F-FDG PET/CT Positivity with Tumor Cytopathology, Galectin-3, PTEN, Ki-67 and NIS Expressions in Thyroid Nodules

ABSTRACT

Objective: The expressions of certain molecular markers have been found to be related with 18F-FDG uptake in differentiated thyroid cancer. The goal of this study was to assess the relationship between NIS, galectin-3, PTEN, Ki-67 expressions and 18F-FDG positron emission tomography positivity in thyroid nodules.

Material and Methods: Fifteen patients with 27 nodules who had incidental focal 18F-FDG uptake in thyroid and underwent total thyroidectomy were included. Immunohistochemical staining with galectin-3, NIS, PTEN, and Ki-67 were performed.

Results: Among the 27 nodules, 19 nodules were diagnosed as papillary thyroid carcinoma. Malignant- positron emission tomography positive (n=13), malignant-positron emission tomography negative (n=6) and benign-positron emission tomography positive nodules (n=8) were classified as group A, B, and C, respectively. PTEN loss was frequent in the malignant nodules compared to the benign ones [19 (42.1%) vs. 1 (12.5%), p=0.01]. NIS positive staining was significantly frequent in older patients (p=0.019). Mean Ki-67 proliferation index, galectin-3, PTEN and NIS expressions were not different between the three groups. SUVmax values were not statistically different between the malignant and benign nodules with focal 18F-FDG uptake (7.7±5.4 vs. 7.0 ±4.4, p=0.8).

Conclusion: The FDG-positron emission tomography/computed tomography positivity was not associated with Galectin-3, NIS, Ki-67 and PTEN expressions. SUVmax values were not different in the malignant and benign nodules but the PTEN loss was frequent in malignant nodules. We suggest that the role of molecular markers in the development of differentiated thyroid cancer with 18F-FDG uptake should be investigated in further studies with a larger patient group.