Prognostic significance of gene amplification of ACTN4 in stage I and II oral tongue cancer

Despite complete resection of the early stage of oral tongue cancer by partial glossectomy, late cervical lymph node metastasis is frequently observed. Gene amplification of ACTN4 (protein name: actinin-4) is closely associated with the metastatic potential of various cancers. This retrospective study was performed to demonstrate the potential usefulness of ACTN4 gene amplification as a prognostic biomarker in patients with stage I/II oral tongue cancer. Fifty-four patients with stage I/II oral tongue cancer were enrolled retrospectively, in accordance with the reporting recommendations for tumour marker prognostic studies (REMARK) guidelines. The copy number of ACTN4 and the protein expression of actinin-4 were evaluated by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. The overall survival time of patients with gene amplification of ACTN4 was significantly shorter than that of patients without gene amplification (P = 0.0010, log-rank test). Gene amplification of ACTN4 was a significant independent risk factor for death in patients with stage I/II oral tongue cancer (hazard ratio 6.08, 95% confidence interval 1.66-22.27). Gene amplification of ACTN4 is a potential prognostic biomarker for overall survival in oral tongue cancer.