The Clinical Significance of the Expression of FEN1 in Primary Osteosarcoma.

Purpose The aim of this research was to investigate the clinical significance of the expression of flap structure-specific endonuclease 1 (FEN1) in primary osteosarcoma. Methods The expression of FEN1 was detected by immunohistochemistry analysis. The association of the expression of FEN1 in osteosarcoma with clinicopathological parameters was analyzed by using χ2 test or Fisher’s exact test. Survival analyses were performed by Kaplan–Meier method and Cox proportional hazards regression model. Results Of the 40 osteosarcoma patients, 19 (47.5%) patients presented with FEN1 high expression, while in the non-neoplastic bone specimens, the FEN1 high expression was observed in 10% (3/30), the positive expression rate in osteosarcoma patients was significantly higher than that of non-neoplastic bone specimens (P< 0.01). Univariate analysis indicated that the progression-free survival (PFS) and overall survival (OS) were correlated with the expression level of FEN1 (PFS, P < 0.001; OS, P = 0.002), Enneking staging (PFS, P = 0.026; OS, P = 0.044) and chemotherapy response (PFS, P = 0.019; OS, P = 0.031). Multivariate analysis demonstrated that FEN1 expression was an independent prognostic factor for the PFS (HR = 4.73, P = 0.002) and OS (HR = 4.01, P = 0.038) of osteosarcoma patients. Conclusion This study showed that FEN1 was overexpressed in osteosarcoma patients and positively associated with poor prognosis of osteosarcoma patients. Further studies should focus on the relative mechanisms and the targeted FEN1 therapies for osteosarcoma.