Positron emission tomography (PET) and PET/CT in thyroid cancer: A systematic review and meta-Analysis

Abstract

Background: Positron emission tomography (PET) and PET/ CT are functional imaging methods that are widely used in diagnostic procedures in oncology. Objectives: The objective of this study was to assess the patient-relevant benefit of PET or PET/CT in patients with thyroid cancer based on a literature review and meta-Analysis. Methods: A systematic review including studies that had been published until December 2013 was performed. To be included, studies had to prospectively investigate patients with thyroid cancer in a clinical setting of staging, restaging, or diagnosing tumour recurrence. Results: Out of 3,506 potentially relevant articles, 29 studies were included. No study directly evaluated the benefits of PET. Twenty-eight studies dealt with the diagnostic accuracy of PET or PET/CT, and 1 study evaluated the prognostic value of PET/CT. The authors showed that a positive result of PET/CT in restaging patients with differentiated thyroid cancer yielded a significant decrease in overall survival (hazard ratio, HR 5.01, CI 3.41-6.62). In patients with suspected recurrence of differentiated thyroid cancer, metaanalysis showed higher sensitivity of PET (89.7%, CI 78-99%) and PET/CT (94.3%, CI 87-97%) compared with conventional imaging (65.4%, CI 32-88%) and comparable results for specificity. Due to the low numbers of studies and patients, meta-Analyses on medullary carcinoma did not produce meaningful results. Conclusion: The patient-relevant benefits of PET or PET/CT in thyroid cancer could not be evaluated satisfactorily based on the included studies. It remains unclear whether higher diagnostic test accuracy leads to changes in therapeutic strategies and better patient-relevant outcomes.