Background: Delphian lymph node (DLN) metastasis has long been considered a prognostic marker of head and neck malignancy. These days, the significance of DLN in thyroid cancer has come to the fore. The objective of the present study was to evaluate the clinical significance of DLN metastasis in patients with papillary thyroid cancer (PTC).
Patients and methods: The study was carried out between July 2009 and December 2011, and DLN was detected in 245 of 898 PTC patients who underwent total thyroidectomy and bilateral central compartment neck dissection. In those 245 patients DLN status was correlated with clinical and pathologic factors, including age, gender, tumor size, extrathyroidal extension (ETE), lymphovascular invasion (LVI), and central and lateral nodal metastasis.
Results: DLN metastasis was found in 20 % of the patients studied (49 of 245), and DLN metastasis was correlated with tumor size, multicentricity, bilaterality, and LVI excluding ETE (all p < 0.05). The proportion of male patients was higher in the DLN metastasis positive group than in the DLN metastasis negative group (34.7 vs. 13.3 %; p < 0.05). Most of the patients (95.9 %) with DLN metastasis had other central neck node metastasis, and the metastatic central lymph node ratio was higher (0.38 ± 0.23 versus 0.09 ± 0.16; p < 0.001) and lateral neck node metastasis was more common (2.6 vs. 32.7 % <0.001) than in patients without DLN metastasis. For central and lateral compartment nodal metastasis, DLN status had sensitivity, specificity, positive and negative predictive values of 100, 37.4, 58.1, and 100 %, and 85.3, 76.2, 97.4, and 32.7 %, respectively. Multivariate analysis showed that the factors affecting DLN involvement were tumor size and LVI. Patients with positive DLN were ~1.6 times more likely to have further central compartment disease and 3.6 times more likely to have lateral compartment disease.
Conclusions: DLN metastasis in patients with PTC is related to a number of poor prognostic factors. Furthermore DLN involvement implies that the patients are predicted to have heavy burden of central neck node metastasis and are more likely to have further lateral neck node metastasis. It is recommended that DLN is evaluated and dissected in all patients with thyroid cancer. If DLN metastasis is suspected, the surgeon should thoroughly dissect the central neck compartment and pay particular attention to the lateral lymph node compartments.