Optimal Serum Thyroid-Stimulating Hormone Level for Patients With Papillary Thyroid Carcinoma After Lobectomy

Abstract

Background: The optimal serum thyroid-stimulating hormone (TSH) level for post-lobectomy papillary thyroid carcinoma (PTC) patients is unclear. The objective of this study was to examine the association of TSH and recurrence in post-lobectomy patients. Methods: Patients who underwent lobectomy for PTC in a single tertiary hospital from January 2000 to December 2014 were enrolled. The mean TSH score of a patient was calculated based on each serum TSH value during follow-up. The TSH value of each follow-up visit was scored as 0-20 with an interval of 0.5 mU/L, and the mean TSH score (MTS) was calculated as the average of all available scores for a patient. The reference range of serum TSH was 0.5-4.0 mU/L (MTS 0-7). Univariate and multivariable analyses were performed with Cox proportional hazards models. Restricted cubic spline (RCS) functions were used to model relationships between MTS and recurrence-free survival (RFS). Results: A total of 2297 patients (median age, 42 years; 1750 (76.2%) female) were analyzed. MTS below (≤0.5), in the lower half (0.5-3), in the upper half (3-7) and above (>7) the reference range were observed in 415 (18.1%), 1376 (59.9%), 409 (17.8%), and 97 (4.2%) patients, respectively. According to the Cox model and RCS, no association was observed between MTS and RFS (adjusted P=0.5071, adjusted P for nonlinear=0.5182). The only RFS difference observed in the stratified univariate analysis was between patients with MTS in the lower half (n=793) and above the reference range (n=54) in the intermediate- to high-risk group (10-year RFS by Kaplan-Meier 82.1% vs 70.5%, log rank p=0.023). Conclusions: Mean serum TSH levels are not associated with recurrence. A normal TSH reference range is recommended for post-lobectomy PTC patients. Funding Information: The study was funded by the CAMS Innovation Fund for Medical Sciences (CIFMS) (Grant no.2016-I2m-1-002) and Beijing Hope Run Special Fund of Cancer Foundation of China (Grant no.LC2018A26) Declaration of Interests: The authors have no conflicts of interest to disclose. Ethics Approval Statement: The study was approved by the Ethics Committee of the Cancer Hospital, Chinese Academy of Medical Sciences. Informed consent was obtained at the time of surgery with surgical consent for general use of clinical information for future studies.