High COX-2 immunostaining in papillary thyroid carcinoma is associated with adverse survival outcomes

BACKGROUND: Thyroid carcinoma is one of the most common malignancies worldwide. More than 70%-80% are papillary thyroid carcinoma (PTC). Many factors influence the PTC pathway of development such as genetic mutations, growth factors, and radiation. More biological understanding of the genetic and molecular pathways is needed in PTC to determine tumor behavior, and initial clinical assessment. OBJECTIVES: Investigate the relation of COX-2 immunostaining in thyroid carcinoma with clinicopathological parameters to assess whether immunostaining results have prognostic significance. DESIGN: Retrospective study SETTING: Pathology department, tertiary care center METHODS: Records of PTC were retrieved and tissue microarrays were constructed. Tissue sections were stained using anti-human COX-2 monoclonal antibody. Immunostaining results were recorded and analysed. MAIN OUTCOME MEASURES: Relationship of COX-2 immunostaining in thyroid carcinoma with clinicopathological parameters. SAMPLE SIZE: 139 tissue samples from 139 patients RESULTS: High versus low COX-2 immunostaining showed no significant differences for most clinicopathological parameters. However, high COX-2 immunostaining showed borderline association with tumor multifocality (P=.05), lower overall (log-rank=8.739 and P=.003), and disease-free survival (log-rank=7.033, P=.008). CONCLUSION: The study showed a positive association of high COX-2 immunostaining with lower survival outcomes in PTC. COX-2 immunostaining could be a potential prognostic factor for survival in PTC. Additional molecular and clinical investigations are needed for further understanding the molecular pathways of COX-2 in PTC and the feasibility of using inhibitors of COX-2 as adjuvant therapy along with current chemotherapy. LIMITATIONS: Relatively low number of PTC variants, and no testing of other thyroid carcinomas. CONFLICT OF INTEREST: None.