Myocardin immunohistochemistry index is associated with clinical prognosis in nasopharyngeal carcinoma: a clinical practice-based cohort study

Abstract

Purpose: Recent findings have implicated the role of myocardin re-expression in carcinogenesisHowever, the clinical functions of myocardin in nasopharyngeal carcinoma (NPC) is not known yet. The purpose for the cohort research was to investigate whether myocardin re-expression level may predict clinical prognosis in NPC patients.Methods: 148 NPC patients were recruited from September, 2005 to September, 2011 with median follow-up time of 4.5 years in a clinical practice setting. At study entry myocardin re-expression of these patients was determined using immunohistochemistry (IHC) and additional 20 normal nasopharyngeal tissues were included as control. Two-sample t-test was used to compare mean myocardin reexpression levels and Chi-square test was used for comparing tumour recurrence rate. Logistic regression analysis was used for tumour local control rate, and log-rank test, Kaplan-Meier estimates and Cox proportional hazard model for disease-free survival and overall survival.Results: Myocardin IHC index was significantly downregulated in NPC samples than in normalnasopharyngeal tissues (mean ± standard deviation, 61.2 ±31.5 vs. 109.9 ±73.6, P= 0.009). However, among NPC patients was observed a roughly V-shaped change of myocardin IHC index according to Tumour T-stage (P=0.067); meanwhile higher IHC level was associated with more tumour recurrence rate in NPC patients (High vs. Low: 21.6% vs. 8.1%; P=0.021). Logistic regression analysis equally showed high myocardin IHC level was an independent risk factor for local tumour control rate regardless of adjustments [High vs. Low: unadjusted Odds Ratio (OR) 0.320, 95% confidence interval (CI): 0.117 to 0.871; P=0.026]. Moreover, higher myocardin IHC level was associated with a marginal but not significant risk increase of disease-free survival [High vs. Low: adjusted Hazard Ratio (HR) 1.760, 95% CI: 0.981 to 3.158; log-rank: P=0.129]. A less obvious trend was observed with regard to overall survival [adjusted HR 1.409, 95% CI: 0.715 to 2.77; log-rank: P=0.745].Conclusion: The study results suggested that high myocardin IHC index level could be a potential clinically prognostic intermediate biomarker for tumour recurrence for NPC patients in routine practice. Large well-designed cohort studies involving IHC re-expression change over time is needed.