(HealthDay News) — Tumor levels of microRNA (miRNA)-222 and miRNA-146b are associated with papillary thyroid cancer (PTC) recurrence, and circulating levels are associated with the presence of PTC, according to a study published online Oct. 28 in Cancer.

James C. Lee, from the Royal North Shore Hospital and University of Sydney in Australia, and colleagues compared tumor miRNA profiles in a retrospectively recruited cohort of patients with recurrent PTC (Rc-PTC) and those without recurrence (NR-PTC). In a prospective analysis, pre- and postoperative circulating miRNA levels were analyzed in patients with newly diagnosed PTC or multi-nodular goiter who were undergoing total thyroidectomy; healthy volunteers were used as a control group.

The researchers found that in Rc-PTC tumors, miRNA-222 and miRNA-146b were overexpressed 10.8 and 8.9-fold, respectively, compared with NR-PTC tumors (P = 0.014 and 0.038, respectively). The levels of miRNA-222 and miRNA-146b were significantly increased in plasma from preoperative PTC patients compared with plasma from healthy volunteers. After total thyroidectomy, significant reductions were observed in the plasma levels of miRNA-222 (2.7-fold) and miRNA-146b (5.1-fold).

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“This study demonstrated that tumor levels of miR-222 and miR-146b are associated with PTC recurrence and that miR-222 and miR-146b levels in the circulation correspond to the presence of PTC,” the authors write. “The potential of these miRNAs as tumor biomarkers to improve patient stratification according to the risk of recurrence and as circulating biomarkers for PTC surveillance warrants further study.”