ABSTRACT
<p><b>OBJECTIVE</b>To investigate the relationship between ALDH1A1 expression and lymph node metastasis (LNM) in papillary thyroid carcinoma (PTC).</p><p><b>METHODS</b>One hundred and fifty-three paraffin-embedded specimens of PTC treated in the Beijing Tongren Hospital of Capital Medical University were selected from January 2006 to December 2013. The expression of ALDH1A1 was detected in both tumor tissues and adjacent non-tumor tissues by immunohistochemistry and several clinicopathological parameters (size, bilaterality, multifocality, tumor border and extrathyroidal extensions) were assessed by HE staining. The correlation of ALDH1A1 expression with LNM was analyzed.</p><p><b>RESULTS</b>In 153 cases of PTC, there were 82 cases with LNM, 126 cases with high ALDH1A1 expression in tumor tissues, and 112 cases with high ALDH1A1 expression in adjacent non-tumor tissues. On univariate analysis, patient age < 45 years, tumor size of 10 mm or more, invasive tumor border, and high ALDH1A1 expression in tumor tissues predicted LNM in PTC (P < 0.05), whereas gender, bilaterality, multifocality, extra-thyroidal extensions and high ALDH1A1 expression in adjacent non-tumor border did not (P > 0.05). On multivariate analysis, invasive tumor border, high ALDH1A1 expression in tumor tissues were found to be independent predictive factors for LNM in PTC (P < 0.05). After a follow-up of 42 months (median time), four patients developed locoregional recurrences, but no distance recurrence or disease related death were seen in 82 patients of follow up. The estimated 5-year locoregional recurrence was 4.88%. Of these four logcoregional recurrences, three involved lymph nodes and one involved the remaining thyroid. The ALDH1A1 expression in tumor tissues was high in all of recurrence cases.</p><p><b>CONCLUSION</b>High ALDH1A1 expression in tumor tissues is correlated with lymph node metastasis in PTC and may be used as an independent predictive factor of LNM, and may improve treatment and follow-up strategies for PTC.</p>