Dynamic risk stratification system in post-lobectomy low-risk and intermediate-risk papillary thyroid carcinoma patients.

Abstract

The dynamic risk stratification (DRS) and its current definition of each response-to-therapy category in post-lobectomy papillary thyroid carcinoma (PTC) patients have not been well studied. This study aimed to validate the DRS system and to investigate useful thyroglobulin (Tg) or anti-Tg antibody (Ab)-related parameters in defining each response-to-therapy category. Retrospective observational study. This historical cohort study included 619 patients with PTC treated by thyroid lobectomy. All enrolled participants were stratified according to the American Thyroid Association (ATA) initial risk stratification system and DRS system, respectively. The association between these stratifications and structural recurrence was evaluated. The median follow-up period was 103months. Structural recurrence occurred in 1.6% of the patients with excellent response, 3.8% of those with indeterminate response, 2.9% of those with biochemical incomplete response, and all patients with structural incomplete response. Five (1.5%) of the low-risk patients and 14 (5.0%) of the intermediate-risk patients had structural recurrence. The disease-free survival curves showed significant differences according to the DRS (P<.001) and ATA initial risk stratification (P=.012), respectively. The proportion of variance explained the DRS system and ATA risk stratification system for structural recurrence was 32.4% and 29.4%, respectively. A thyroid-stimulating hormone (TSH) level >2.75μU/mL at 1year after the initial operation (P<.001) was the only valuable risk factor for structural recurrence identified in this study. The long-term postoperative management of PTC patients treated with thyroid lobectomy could be guided based on the DRS.