Association between surgical extent and recurrence in unilateral intermediate- to high-risk papillary thyroid cancer.

[BACKGROUND] Guidelines recommend total thyroidectomy (TT) to facilitate radioactive ablation and serological follow-up for intermediate- to high-risk papillary thyroid carcinoma (PTC). However, the association between surgical extent and tumor recurrence in these patients has not been well validated. We aimed to examine the association between the extent of surgery and recurrence in patients with completely resected unilateral intermediate- to high-risk PTC.

[METHODS] Patients with completely resected unilateral PTC from 2000 to 2017 in a single institute were reviewed. Those who had extrathyroidal extension (ETE) or lymph node metastasis (LNM, cN1 or pN1 > 5 lymph nodes involved) were included for analysis. Cox proportional hazards models were applied to measure the association between surgical extent and recurrence-free survival (RFS) while adjusting for patient demographic, clinicopathological and treatment variables.

[RESULTS] A total of 4550 patients (mean[SD] age, 43.0[11.7] years; 3379 women[74.3%]) were included. Of these patients, 2262(49.7%), 656(14.4%), 1032(22.7%), and 600 (13.2%) underwent lobectomy, TT, lobectomy + neck dissection (ND) and TT + ND, respectively. With a median follow-up period of 68 months, after multivariate adjustment, lobectomy was associated with a compromised RFS compared with other surgical extents (HR[95%CI], TT 0.537[0.333-0.866], P = 0.011, lobectomy + ND 0.531[0.392-0.720] P < 0.0001, TT + ND 0.446[0.286-0.697] P < 0.0001). RFS was similar between the two extents with ND (lobectomy + ND, HR [95%CI], 1.196 [0.759-1.885], P = 0.440).

[CONCLUSION] Lobectomy alone is associated with an elevated recurrence risk in patients with unilateral intermediate- to high-risk PTC compared with larger surgical extents. However, lobectomy and ND may provide similar tumor control compared with the conventional approach of TT and ND.