Immunohistochemical Staining of E-cadherin is Inversely Correlated with the Presence of Metastases of Papillary Thyroid Carcinoma

Background:
Papillary thyroid carcinoma (PTC) is the most common type of primary thyroid cancer with a low incidence of distant metastases. A few studies have explored the correlation between immunohistochemical staining of PTC and risk of tumor metastases and extrathyroidal extension (ETE).

Aim:
To evaluate the correlation between the intensity of different immunohistochemical marker staining in PTC and the risk for extrathyroidal extension or metastases.

Methods:
The study included patients who underwent complete or partial thyroidectomy for PTC at Bnai-Zion Medical Center. Thyroid tissues were immunohistochemically stained for different tumor proliferative markers: Minichromosome maintenance protein 2 (MCM2), Ki-67 labeling index, E-Cadherin, Neuropilin-1 and Metallothionein. The correlation between the intensity of each staining and tumor extrathyroidal extension and metastases were evaluated.

Results:
The study included 44 patients: 21 patients with thyroid confined PTC who had neither ETE nor metastases, 12 patients with PTC with ETE without known metastases, and 11 PTC patients who had cervical lymph nodes metastases or distant metastases. No staining correlated with extrathyroidal extension. The intensity of E-Cadherin staining was significantly lower in PTCs with metastases than thyroid confined PTCs and PTCs with extrathyroidal extension (P 0.028 and 0.021, respectively). The intensity of the staining of the immunohistochemical markers: MCM2, Neuropilin-1 and Metallothionein did not correlate with presence of metastases. Ki-67 nuclear staining was significantly lower in PTCs with ETE than PTCs with metastases, however it did not significantly differentiate between thyroid confined tumors and metastatic ones.

Conclusions:
Immunohistochemical staining of E-Cadherin significantly and inversely correlated with the presence of metastases of papillary thyroid carcinoma.