RACK1 and RPS6 as independent prognostic biomarkers in oral squamous cell carcinoma: a five-year survival analysis

This study aimed to investigate the Clinicopathologic & prognostic significance of Receptor for Activated C Kinase 1 (RACK1) and Ribosomal Protein S6 (RPS6) in Oral Squamous Cell Carcinoma (OSCC) through immunohistochemistry.

Formalin-fixed, paraffin-embedded tumor tissues of 100 OSCC cases who were treated primarily via surgery were retrieved and immunohistochemical analysis was done for RACK1 & RPS6. Clinicopathological data was gathered for these subjects and each was followed up for a period of 5 years from initial diagnosis. Association of expression of marker with clinicopathological parameters was done using Chi-square test. Prognostic significance was evaluated with Cox proportional hazards regression, Kaplan-Meier method, and receiver operating characteristic (ROC) analyses.

High expression of RACK1 and RPS6 was significantly associated with age (p = .005, p = .04), nodal involvement (p = .01, p = .05), histopathological grading (p = <0.001), treatment (p = 0.04, p = 0.02), and recurrence (p = .001, p = .03). Subjects with high expression of RACK1 & RPS6 were significantly associated with reduced overall (OS), disease-free (DFS), and cancer-specific survival (CSS) (p < 0.001). Co-expression of both markers correlated with the worst prognosis in terms of OS, DFS and CSS (p < 0.001). Multivariate Cox Regression analysis showed that both the markers can serve as independent prognostic marker in OSCC. Strong positive linear correlation (R² = 0.718) was observed between expression of RACK1 & RPS6. ROC analysis demonstrated high sensitivity and specificity of both the markers in predicting OS, DFS and CSS.

The results of the present study suggest that RACK1 & RPS6 are associated with tumor progression and invasion in OSCC. Individual as well as combined expression of both the markers may be used as prognostic biomarker in OSCC for patient stratification and personalized treatment planning.