Postoperative ultrasonography surveillance in patients with follicular thyroid carcinoma: a multicenter study

Objective This study aimed to evaluate the locoregional recurrence rate of follicular thyroid carcinoma (FTC) and to assess the appropriate frequency of postoperative ultrasonography (US) surveillance for detecting tumor recurrence. Methods The review boards of the seven participating institutions approved this study. From 2000 to 2011, 186 patients underwent at postoperative US at least once; US was performed by experienced radiologists at each institution. Based on the US and histopathological results, locoregional tumor recurrence was assessed. Results The T stages of the 186 patients were T1a (8.1%), T1b (21.5%), T2 (39.8%), T3 (30.6%), T4a (0%), and T4b (0%). The N stages were unknown (24.2%), N0 (71.5%), N1a (3.2%), and N1b (1.1%), and the M stages unknown (29.6%), M0 (66.1%), and M1 (4.3%). Tumors recurred in only 6 (3.2%) patients during the follow-up period over 5 years. Among them, no patients showed the initial suspicion of recurrences on routine follow-up US. The session number and interval of postoperative US differed significantly between patients with recurrence and those without recurrence. The mean interval of postoperative follow-up US at the first detection time of tumor recurrence was 37.5 +/- 18.5 months (range 9-62 months). Significantly more FTCs were at an advanced N and M stage in the recurrence group than in the non-recurrence group (p < 0.05). Conclusions Routine postoperative US surveillance may be unnecessary for detecting tumor recurrence after thyroid surgery in FTC patients.