Clinical impact of coexistent chronic lymphocytic thyroiditis on central lymph node metastasis in low- to intermediate-risk papillary thyroid carcinoma: The MASTER study.

BACKGROUND: The clinicopathological impact of chronic lymphocytic thyroiditis on patients with papillary thyroid carcinoma patients is still controversial. This study aimed to evaluate the clinicopathologic differences and risk factors for central lymph node metastasis based on the presence of coexistent chronic lymphocytic thyroiditis in patients with low- to intermediate-risk papillary thyroid carcinoma. METHODS: The medical records of 1,022 patients with low- to intermediate-risk papillary thyroid carcinoma who underwent lobectomy and central neck dissection between June 2020 and March 2022 were reviewed. Differences in clinicopathological factors were analyzed in patients with papillary thyroid carcinoma with or without chronic lymphocytic thyroiditis. Furthermore, risk factors for central lymph node metastasis in patients with low- to intermediate-risk papillary thyroid carcinoma with or without chronic lymphocytic thyroiditis were evaluated. RESULTS: Among the 1,022 patients with low to intermediate-risk papillary thyroid carcinoma, 102 (10.0%) had coexisting chronic lymphocytic thyroiditis. Female sex (odds ratio = 3.536, P = .001, 95% confidence interval 1.781-8.069), a multifocal tumor (odds ratio = 2.162, P = .001, 95% confidence interval 1.358-3.395), and angiolymphatic invasion (odds ratio = 0.365, P < .001, 95% confidence interval 0.203-0.625) were independent factors associated with patients who had coexisting chronic lymphocytic thyroiditis compared to those without chronic lymphocytic thyroiditis. There were 358 (35%) patients who had central lymph node metastasis. Multivariate analysis showed that younger age (odds ratio = 0.667, P = .013, 95% confidence interval 0.482-0.555), male sex (odds ratio = 0.549, P < .001, 95% confidence interval 0.402-0.751), tumor size >1 cm (odds ratio = 1.454, P = .022, 95% confidence interval 1.053-2.003), extrathyroidal extension (odds ratio = 1.874, P < .001, 95% confidence interval 1.414-2.486), and angiolymphatic invasion (odds ratio = 3.094, P < .001, 95% confidence interval 2.339-4.101) were risk factors for central lymph node metastasis. Angiolymphatic invasion (odds ratio = 11.184, P < .001, 95% confidence interval 3.277-46.199) was identified as the sole independent risk factor for central lymph node metastasis in patients with papillary thyroid carcinoma with coexisting chronic lymphocytic thyroiditis. CONCLUSION: Our data suggest that patients with low to intermediate-risk papillary thyroid carcinoma with coexistent chronic lymphocytic thyroiditis exhibit different clinical features than patients with papillary thyroid carcinoma without chronic lymphocytic thyroiditis. Additionally, the presence of chronic lymphocytic thyroiditis may be considered a potential factor against central lymph node metastasis.

Feasibility of active surveillance in patients with clinically T1b papillary thyroid carcinoma ≤1.5 cm in preoperative ultrasonography: MASTER study.

Objective: Active surveillance (AS) is generally accepted as an alternative to immediate surgery for papillary thyroid carcinoma (PTC) measuring ≤1.0 cm (cT1a) without risk factors. This study investigated the clinicopathologic characteristics of PTCs measuring ≤2.0 cm without cervical lymph node metastasis (cT1N0) by tumor size group to assess the feasibility of AS for PTCs between 1.0 cm and 1.5 cm (cT1b≤1.5). Design: This study enrolled clinically T1N0 patients with preoperative ultrasonography information (n= 935) from a cohort of 1259 patients who underwent lobectomy and were finally diagnosed with PTC from June 2020 to March 2022. Results: The cT1b≤1.5 group (n = 171; 18.3 %) exhibited more lymphatic invasion and occult central lymph node (LN) metastasis with a higher metastatic LN ratio than the cT1a group (n = 719; 76.9 %). However, among patients aged 55 years or older, there were no significant differences in occult central LN metastasis and metastatic LN ratio between the cT1a, cT1b≤1.5, and cT1b>1.5 groups. Multivariate regression analyses revealed that occult central LN metastasis was associated with age, sex, tumor size, extrathyroidal extension, and lymphatic invasion in patients under 55, while in those aged 55 or older, it was associated only with age and lymphatic invasion. Conclusion: For PTC patients aged 55 years or older with cT1b≤1.5, AS could be a viable option due to the absence of a significant relationship between tumor size and occult central LN.