Is conformal thyroidectomy feasible? A 5-10-year follow-up study of residual thyroid in 2512 cases after thyroidectomy.

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, and the balance between surgical extent (particularly non-total thyroidectomy [non-TX]) and postoperative recurrence risk in the residual thyroid remains a key clinical concern. This single-center retrospective study analyzed 2512 patients with unilateral PTC who underwent non-TTx between January 2014 and December 2024 and completed 5-10 years of follow-up evaluations, aiming to determine the recurrence rate in residual thyroid and related risk factors. METHODS: The Kaplan-Meier method was used to calculate cumulative recurrence-free survival (RT-RFS) in the residual thyroid. Independent risk factors were identified through univariate χ² tests and multivariate logistic regression analysis. The effect size for between-group differences in continuous variables was calculated using Cohen's d. RESULTS: The overall recurrence rate was 5.8% with 5- and 10-y RT-RFS rates of 95.4% and 94.2%, respectively. Univariate analysis demonstrated significant associations between recurrence and age > 55 y, increased tumor size (T1a-T3), multifocality, preoperative subclinical hypothyroidism, and postoperative TSH > 2.0 mIU/L (all P < 0.05). Multivariate regression analysis confirmed tumor size (T1b/T2/T3 vs. T1a: OR = 2.253/5.053/19.452), multifocality (OR = 1.908), and postoperative TSH > 2.0 mIU/L (OR = 2.193) as independent risk factors for residual thyroid recurrence (all P < 0.05). However, neither the surgical extent of non-TTx, nor age, gender, preoperative subclinical hypothyroidism, and coexisting Hashimoto's thyroiditis are independent driving factors, and confirmed that there is no significant association between residual thyroid volume and postoperative recurrence risk. CONCLUSION: For patients with unilateral, unifocal PTC classified as T1a, we propose that conformal thyroidectomy represents a clinically appropriate and feasible alternative to unilateral thyroid lobectomy.