*Article* **Optimal Surgical Extent in Patients with Unilateral Multifocal Papillary Thyroid Carcinoma**

**Joohyun Woo and Hyungju Kwon \***

Department of Surgery, Ewha Womans University Medical Center, Seoul 07985, Korea; jwoo@ewha.ac.kr

**\*** Correspondence: hkwon@ewha.ac.kr; Tel.: +82-2-2650-5025

**Simple Summary:** Around 30% of patients with papillary thyroid cancer (PTC) have multifocality. As tumor multifocality could increase the risk of recurrence in patients with PTC, more aggressive treatments, including total thyroidectomy and higher-dose radioiodine, are commonly used to treat patients with multifocal PTC. However, it is unclear whether aggressive treatment can decrease the risk of recurrence. Our study of 718 patients demonstrated that thyroid lobectomy showed comparable recurrence-free survival to that of total thyroidectomy. Moreover, our findings indicated that thyroid lobectomy could be safely performed on multifocal PTC patients with high-risk factors, such as large tumor size or lymph node metastasis. In conclusion, thyroid lobectomy was not associated with the risk of recurrence in patients with multifocal PTCs. Multifocality in PTC may not always require aggressive surgery.

**Abstract:** Multifocality increases the risk of recurrence in patients with papillary thyroid carcinoma (PTC); however, it is unclear whether multifocality justifies more extensive or aggressive surgical treatment. Here, we evaluated the effect of the operative extent on the recurrence-free survival (RFS) of patients with multifocal PTC. Between 2010 and 2019, 718 patients with unilateral multifocal PTC were enrolled; 115 patients (16.0%) underwent ipsilateral thyroid lobectomy, and 606 patients (84.0%) underwent total thyroidectomy. With a mean follow up of 5.2 years, RFS was comparable between the total thyroidectomy and lobectomy groups (*p* = 0.647) after adjusting for potential confounders. Multivariable Cox regression analysis also demonstrated that the operative extent was not an independent predictor of recurrence (HR 1.686, 95% CI: 0.321–8.852). Subgroup analyses further indicated that both total thyroidectomy and thyroid lobectomy resulted in comparable RFS for multifocal PTC patients with other high-risk factors, including tumor size > 1 cm (*p* = 0.711), lymph node metastasis (*p* = 0.536), and intermediate ATA risk of recurrence (*p* = 0.682). In conclusion, thyroid lobectomy was not associated with the risk of recurrence in patients with multifocal PTCs. Multifocality in PTC may not always require aggressive surgery.

**Keywords:** papillary thyroid carcinoma; multifocality; lobectomy; operative extent
