Prognostic significance of tumor volume in nasopharyngeal carcinoma

Objective To investigate the prognostic significance of primary and residual tumor volume in nasopharyngeal carcinoma. Methods 56 patients were included in the study. Diameters of tumors were measured from CT and MR film hardcopies. Diameter-based measurements were computed as an ellipsoid (V = 4/3·π·d1·d2·d3) to calculate diameter-based volume. It was investigated whether primary tumor volume provided prognostic information about local regional recurrence free survival (LRRFS), disease free survival (DFS), distant metastasis free survival (DMFS) and overall survival (OS) by monovariant and multivariant analysis. Kaplan–Meier survival analysis method and log-rank test were used to estimate survival analysis (95% confidence interval). Cox regression test was used for two variant and multivariant survival analysis. Statistical Package for Social Sciences (SSSP) 10.0 for Windows programme was used for data analysis. Results In the multivariate analysis, in the patients with tumor volume more than 60 ml, local regional recurrence more frequently developed. The relationship between tumor volume and local regional recurrence was found significant (p = 0.053). In the monovariate analysis, primary tumor volume was found to be a significant predictive value on DFS and DMFS. In the patients with tumor volume below 20 ml, DFS was 60%, whereas in the patients with tumor volume above 60 ml, DFS was 0% (p = 0.007). The prevalence were 68% and 0% in the patients group that had tumor volume below 30 ml and above 60 ml respectively. DMSF ratios in the patients with primary tumor volume below 20 ml and above 60 ml were 86.67% and 33.3% respectively. The residual tumor volume (RTV) at first control after treatment was found to be a significant prognostic factor on LRRFS (p = 0.03). Conclusion The foundation of new T staging systems that consists of PTV that was found as an independent prognostic factor alone in multivariate statistical analysis may precede better prediction of prognosis and more appropriate treatment of patients having different prognostic factors. RTV in the first control after treatment was a significant prognostic factor on LRRFS.