Thyroid cancer is the most prevalent endocrine cancer worldwide. Certain histological subtypes of papillary thyroid carcinoma (PTC) exhibit aggressive behavior, with poor clinical outcomes. Long non-coding RNAs (lncRNAs) have emerged as critical regulators of various biological processes, making them promising candidates for cancer biomarkers.

This study aimed to investigate the roles of lncRNAs, specifically prostate cancer-associated transcript 1 (PCAT-1) and Fetal-lethal non-coding developmental regulatory RNA (FENDRR), in the pathogenesis of thyroid carcinoma. Additionally, we evaluated their potential as diagnostic and prognostic markers in PTC.

Forty fresh thyroid cancer samples and 36 control goiter tissue samples were analyzed for gene expression levels of PCAT-1 and FENDRR via quantitative real-time polymerase chain reaction (PCR), and Associations with clinicopathological characteristics were analyzed. Receiver operating characteristic (ROC) curves were used to evaluate diagnostic accuracy, and the Kaplan-Meier technique was used to analyze survival. A Cox proportional-hazards regression model was used to assess the effects of several risk variables on survival.

Compared with controls, PTC patients predented significantly increased PCAT-1 expression and decreased FENDRR expression, with high diagnostic accuracy according to ROC curve analysis. Patients with lower FENDRR expression had shorter recurrence-free survival, according to Kaplan-Meier analysis. Low FENDRR gene expression, a tumor size greater than 2 cm, invasion into the capsule, and other lobe malignancies remained significant independent prognostic factors for PTC recurrence according to Cox proportional hazards regression analysis.

This study is the first to investigate the expression patterns of PCAT-1 and FENDRR in thyroid cancer. These results indicate that both lncRNAs could be used as diagnostic biomarkers to differentiate PTC from benign thyroid tumors. Furthermore, decreased expression of FENDRR might be used as an independent prognostic factor for predicting PTC recurrence.