Associate Professor College of Medicine, Ewha Womans University, Seoul-t'ukpyolsi, Republic of Korea
Introduction Multifocality in papillary thyroid carcinoma (PTC) increases the risk of recurrence. Some recent studies have suggested that multifocality and its bilaterality have different impact on recurrence in patients with PTC. However, it is still unclear if these factors can improve the accuracy of the recurrence pre-diction model. Methods Between 2012 and 2019, 1288 patients with PTC underwent total thyroidectomy at Ewha Womans University Medical Center. Patient demographics and tumor characteristics data pertaining to the tumor size, ETE, total number of tumors, bilaterality, LN metastasis, resection margin statue, and coexisting Hashimoto thyroiditis were collected. Primary end point of this study was the 5-year recurrence-free survival (RFS). Results Follow-up period was 6.4 ± 3.3 years (IQR 4.4–8.7 years). A total of 387 (30.0%) patients had bilateral PTC, whereas 114 (8.8%) patients had unilateral multifocal tumors and 114 (61.1%) had unifocal tumor. The 5-year RFS rate was 98.0% in patients with unifocal tumor, 97.0% with unilateral multifocal tumors, and 95.8% with bilateral PTC (p=0.027). Cox proportional hazards analysis indicated that bilaterality (HR 2.145, 95% CI 1.085-4.241), male sex (HR 2.100, 95% CI 1.019-4.325), tumor size (HR 1.706, 95% CI 1.291-2.255) and N1b LN metastasis (HR 3.586, 95% CI 1.212-10.61) could be an independent predictor of recurrence, while unilateral multifocality (HR 1.279, 95% CI 0.363-4.506) did not increase the risk of recurrence. Conclusion Patients with bilateral PTC had worse 5-year RFS, compared to those with multifocality. Bilaterality offers better predictability of recurrence in patients with PTC.