Chronic Lymphocytic Thyroiditis is a Protective Factor for Lymph Node Metastasis in Papillary Thyroid Carcinoma: A Propensity Score Matching Analysis.

Aims/Background The connection between lymph node (LN) metastases in papillary thyroid carcinoma (PTC) and chronic lymphocytic thyroiditis (CLT) has been examined in a number of prior investigations. However, there is ongoing debate over the effect of CLT on LN metastasis in PTC. In order to explain the relationship between CLT and LN metastasis more convincingly, we aimed to retrospectively review clinical data to investigate the correlation between CLT and LN metastasis in PTC using propensity score matching (PSM). Methods Data on PTC patients at Wenzhou Central Hospital were collected retrospectively between 1 January 2018, and 31 March 2022. The patients were split into two groups based on whether they had CLT or not. The clinicopathological characteristics of the two groups were compared using a PSM analysis. The relationship between CLT and LN metastases was analyzed using logistic regression analysis. Results Among the 773 PTC patients collected and examined, 213 showed simultaneous CLT. Prior to PSM, patients with CLT displayed a significantly lower incidence of LN metastasis (34.3% VS 44.8%, p = 0.008), a lower metastatic LN ratio (0 (0, 0.17) VS 0 (0, 0.38), p = 0.011), and a greater number of LNs dissected (7 (5, 11) VS 5 (3, 7), p < 0.001). These differences persisted after the PSM of 208 pairs. After PSM, patients with CLT displayed a significantly lower incidence of LN metastasis (35.0% VS 44.7%, p = 0.045), a lower metastatic LN ratio (0 (0, 0.17) VS 0 (0, 0.33), p = 0.038), and a higher number of dissected LNs (7 (5, 11) VS 5 (3, 7), p ≤ 0.001). Additionally, the multivariate logistic regression analysis indicated that CLT had a protective role against LN metastasis in both the matched group (odds ratio (OR), 0.62; 95% confidence interval (CI): 0.39-0.96; p = 0.032) and the unmatched group (OR, 0.63; 95% CI: 0.44-0.91; p = 0.014). Conclusion Our data indicate that CLT may protect against LN metastases in patients with PTC. Patients having PTC with coexisting CLT have fewer LN metastases, a greater number of LNs dissected, and a lower metastatic LN ratio.