Negative Expression of CPSF2 Predicts a Poorer Clinical Outcome in Patients with Papillary Thyroid Carcinoma

Background: The BRAF^V600E mutation is a promising prognostic biomarker for patients with papillary thyroid carcinoma (PTC), but its prevalence differs widely among different geographic regions. A recent study reported that loss of the Cleavage and Polyadenylation Specificity Factor Subunit 2 (CPSF2) gene was associated with increased cellular invasion, cancer stem cells, and aggressiveness of PTC. This study aimed at evaluating CPSF2 protein expression as a prognostic marker for PTC in a region with a high prevalence of the BRAF^V600E mutation, Korea. Methods: This study included 159 patients with classical PTC who underwent a total thyroidectomy and received ablative doses of ¹³¹I. The expression of CPSF2 protein was evaluated by immunohistochemistry and graded semi-quantitatively. The presence of the BRAF^V600E mutation was evaluated by direct sequencing. Results: Negative protein expression of CPSF2 was observed in 34 (21.3%) of the 159 PTCs. In multivariate analysis, negative CPSF2 expression was significantly associated with cervical lymph node metastasis (odds ratio [OR]=2.56, p=0.28), and distant metastasis (OR=3.48, p=0.02). After adjusting for age, sex, tumor size, extrathyroidal invasion, lymphovascular invasion, and the BRAF^V600E mutation, the CPSF2-negative group had a significantly lower recurrence-free survival compared to the CPSF2-positive group (hazard ratio=2.14, p=0.03). Conclusion: Negative protein expression of CPSF2 is independently associated with a poor clinical outcome in PTC. CPSF2 could be a useful prognostic marker for PTC in regions with a high prevalence of the BRAF^V600E mutation.