Thyroxine Replacement Therapy After Lobectomy for Low-risk Papillary Thyroid Carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer and has a good prognosis.According to the 2015 American thyroid association (ATA) guidelines, no gross extrathyroidal extension and the number of pathological lymph node micrometastases (\<0.2cm) ≤5 were defined as the low recurrence risk group. After total thyroidectomy and radioiodine treatment, the probability of disease-free status (irritant Tg\<1ng/ml, no evidence of other disease recurrence) is about 78%-91%, and the probability of structural recurrence is about 1%-10%. In recent years, due to the further understanding of PTC, surgeons tend to become more conservative in treatment, such as active observation or reducing the extent of surgery. The indication for lobectomy has been extended to tumors \<4cm without extrathyroidal extension and clinical lymph node metastasis. For patients treated with lobectomy, current guidelines recommend that Thyroid Stimulating Hormone (TSH) be controlled at 0.5-2 mU/L, but evidence on the prognostic benefits of this TSH inhibition range is lacking.In recent years, a number of studies have suggested that if postoperative TSH in low-risk patients after lobectomy is acceptable within the reference range, it means that a considerable number of patients have a high probability of not receiving thyroxine replacement therapy after surgery, which can significantly improve their quality of life.A previous retrospective study from our institute showed no significant association between TSH levels after lobectomy and prognosis.The aim of this study was to evaluate the benefits and risks of postoperative TSH levels within the reference range (0.4-5 mU/L) in patients with low-risk papillary thyroid cancer who underwent lobectomy.In order to improve the effect of longer recurrence and death time of PTC, the investigators also performed postoperative thyroglobulin and its antibody for short-term treatment response evaluation.