Clinical implications of Delphian lymph node metastasis in papillary thyroid carcinoma

Abstract

Background: As is known, identifying risk factors precisely for lymph node metastasis (LNM) plays a vital role in initial treatment for papillary thyroid carcinoma (PTC). Nonetheless, whether Delphian lymph node (DLN) metastasis has value in predicting LNM remains an open question. This study covered a sample of 1,575 patients, which is the largest sample group so far, aiming to assess the predictive validity of DLN metastasis in PTC.

Methods: This retrospective cohort study was conducted with 1,575 eligible PTC patients who underwent thyroid operation between July 2013 and December 2018 and clinicopathologic parameters of patients with DLN metastasis were compared with those without DLN metastasis.

Results: The incidence of DLN metastasis, according to our research samples, is 24.4% (384/1,575 patients). And results show that DLN positivity was closely associated with adverse prognostic factors including younger age, larger tumor size, extrathyroid extension, tumor location in the isthmus or upper lobe of the thyroid, number of LNM >5, higher recurrence. After carefully adjusting important confounding factors, we find that in multivariate logistic regression analyses, DLN metastasis is an independent predictor for both central LNM (CLNM, adjusted OR =7.81, P<0.001) and lateral LNM (LLNM, adjusted OR =3.40, P<0.001). Moreover, the stratified analyses also show convincing evidence of a positive correlation between DLN metastasis and LNM in levels II-IV in the vast majority of subgroups.

Conclusions: The present study suggests that DLN metastasis is an independent risk factor for CLNM and LLNM of levels II-IV. The cervical lymph nodes should be meticulously evaluated to guide tailored treatment during operation in patients with DLN involvement.

Keywords: Delphian lymph nodes metastasis; Papillary thyroid carcinoma (PTC); central lymph node metastasis (CLNM); lateral lymph node metastasis (LLNM).

Figure 1

Flow diagram of patients selection. DLN, Delphian lymph node; PTC, papillary thyroid carcinoma.

Figure 2

Comparison of tumor size (A) and the number of metastatic LN (B) between the DLN-negative group and the DLN-positive group. LN, lymph node; DLN, Delphian lymph node.

Figure 3

Incidence of central lymph node metastasis in all patients (A) and in patients with T1-T2, noninvasive, cN0 tumors (B) according to clinical nodal and the DLN status. cN0, clinical lymph node negative; cN1, clinical central or lateral lymph node positive; DLN, Delphian lymph node.

Figure 4

Subgroup analysis of association between level II metastasis and DLN metastasis according to baseline characteristics. DLN, Delphian lymph node; ETE, extrathyroid extension; CLNM, central lymph node metastasis; OR, odds ratio; CI, confidence interval.

Figure 5

Subgroup analysis of association between level III metastasis and DLN metastasis according to baseline characteristics. DLN, Delphian lymph node; ETE, extrathyroid extension; CLNM, central lymph node metastasis; OR, odds ratio; CI, confidence interval.

Figure 6

Subgroup analysis of association between level IV metastasis and DLN metastasis according to baseline characteristics. DLN, Delphian lymph node; ETE, extrathyroid extension; CLNM, central lymph node metastasis; OR, odds ratio; CI, confidence interval.