Positron Emission Tomography (PET) and PET/CT in Thyroid Cancer: A Systematic Review and Meta-Analysis

Positron emission tomography (PET) and PET/CT are functional imaging methods that are widely used in diagnostic procedures in oncology.

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.

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.

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, meta-analysis 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.

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.