Analysis of predictability of F‐18 fluorodeoxyglucose‐PET/CT in the recurrence of papillary thyroid carcinoma

Whether preoperative F‐18 fluorodeoxyglucose (FDG)‐positron emission tomography/computed tomography (PET/CT) can predict recurrence of papillary thyroid carcinoma (PTC) remains unclear. Herein, we evaluated the potential of primary tumor FDG avidity for the prediction of tumor recurrence in PTC patients. A total of 412 PTC patients (72 males, 340 females; age: 47.2 ± 12.2 years; range: 17–84 years) who underwent FDG‐PET/CT prior to total thyroidectomy (n = 350), subtotal thyroidectomy (n = 2), or lobectomy (n = 60) from 2007 to 2011 were analyzed. The predictive ability for recurrence was investigated among various clinicopathological factors, BRAFV 600E mutation, and preoperative FDG avidity of the primary tumor using Kaplan–Meier (univariate) and Cox proportional hazards regression (multivariate) analyses. Of the 412 patients, 19 (4.6%) experienced recurrence, which was confirmed either by pathology (n = 17) or high serum thyroglobulin level (n = 2), during a mean follow‐up period of 43.9 ± 16.6 months. Of the 412 patients, 237 (57.5%) had FDG‐avid tumors (maximum standardized uptake value, 7.1 ± 7.0; range: 1.6–50.5). Kaplan–Meier analysis revealed that tumor size (P = 0.0054), FDG avidity of the tumor (P = 0.0049), extrathyroidal extension (P = 0.0212), and lymph node (LN) stage (P < 0.0001) were significant predictors for recurrence. However, only LN stage remained a significant predictor in the multivariate analysis (P < 0.0001). Patients with FDG‐avid tumors had higher LN stage (P < 0.0001), larger tumor size (P < 0.0001), and more frequent extrathyroidal extension (P < 0.0001). In conclusion, FDG avidity of the primary tumor in preoperative FDG‐PET/CT could not predict the recurrence of PTC. LN stage was the only identified predictor of PTC recurrence.