Endocrine Abstracts

Objectives: We previously reported the outcome of 1-year follow-up of 2013 DTC patients in the DTCC (differentiated thyroid cancer in China) 1^st stage Study. Using the retrospectively gathered information, we sought to observe the long-term follow-up and prognosis of these patients with DTC undergoing thyroid surgery.

Methods: This multicenter, noninterventional study was conducted at eight tertiary hospitals across China. Data from the patients with more than five years of follow-up from the date of signing the informed consent form (ICF) in the DTCC 1^st study were collected retrospectively. Eligible patients were those recruited into DTCC 1^st study with intermediate risk or high risk of recurrence. We categorized the patients into five groups according to a time-weighted average of serum TSH (TW-TSH): lowest (<0.1 mIU/l), below (0.1-0.5 mIU/l), in the lower half (0.5-2 mIU/l), in the upper half (2-4 mIU/l), and above (>4 mIU/l) the reference range.

Results: 1262 patients (mean age 48 years) who have completed follow-up were analyzed. After a median follow-up of 6.5 years (range, 1.0-8.3 years ), the recurrent disease was observed in 33 patients (2.6%), five patients died (0.4%), and 11 patients (0.9%) had reoperation or multiple surgeries. Of the 1178 patients with sufficient follow-up data, 89.0%, 4.6%, 2.5%, and 3.9% were classified as having an excellent response, biochemical incomplete response, structural incomplete response, and indeterminate response during the first postoperative visit in this study, respectively. By univariate analysis, no difference was demonstrated in DFS (disease-free survival) according to the surgical extent (Total/near-total thyroidectomy vs. other, P = 0.74); a similar lack of difference was seen in radioiodine (RAI) treatment application (RAI vs. no RAI, P = 0.65). Based on the Cox model, no association was observed between TW-TSH and DFS in the overall cohort (P = 0.07). However, patients with TW-TSH in the lower half showed improved DFS compared with those with a TW-TSH above the reference range (risk ratio [RR] 0.37, P = 0.01).

Conclusions: This was the first large-scale retrospective study of how patients with DTC in China are treated in actual clinical practice. The results show that the recurrence rate is low; the reason may be that high-volume surgeons in top tertiary hospitals conducted the surgeries, and nearly all patients underwent lymph node dissection during the initial surgery.