Significance and predictive value of Delphian lymph node in papillary thyroid carcinoma

Backgroud Delphian lymph node metastasis (DLN) is common in papillary thyroid cancer(PTC). However, there have been limited studies that have specifically examined the clinicopathological characteristics of DLN metastasis in PTC. We objected to investigate the incidence, risk factors and predictive value of DLN in papillary thyroid carcinoma. Methods: : Clinical pathological features and metastatic risks were statistically analyzed by reviewing 1837 patients with papillary thyroid carcinoma, who received their first operation in our department between January 2018 and July 2021. Results: : Of the 1837 patients included in the study, DLN was detected in 925 patients (50.7%), 409 patients (22.3%) had confirmed DLN metastasis. In univariate analysis, DLN metastasis was correlated with age(≥55y), tumor size(≥1cm）, bilateral cancer, mulifocality, tumor location(isthmus cancer), central lymph node metastasis(CLNM) and later lymph node metastasis(LLNM). However, it was not correlated with sex distribution, tumor size, thyroiditis, thyroid stimulating hormone(TSH) level and BRAF mutation. Multivariate analysis showed that CLNM(p=0.03), LLNM(p=0.025)，bilateral cancer and tumor location(p=0.017) were independent risk factors of DLN metastasis. DLN involvement was mildly predictive of CLNM(sensitivity=29.76%, specificity=87.06%, positive predictive values=74.08%, negative predictive values =49.93%, positive likelihood ratio=2.30, negative likelihood ratio=0.81), moderately predictive of LLNM(sensitivity=49.36%, specificity=85.01%, positive predictive values=46.94%, negative predictive values =86.20%, positive likelihood ratio=3.29, negative likelihood ratio=0.60). Conclusions: : Bilateral cancer, CLNM, LLNM and isthmus cancer were independent risk factors of DLN metastasis. DLN metastasis could be used as a predictor of central and lateral lymph node metastasis. Positive DLN should be an alert signal to careful evaluate central and lateral lymph node in thyreoidectomy.