The prognostic influence of prevertebral space involvement in nasopharyngeal carcinoma

Objectives: The purpose of this study was to evaluate the effect of prevetebral space involvement on treatment outcomes in patients with nasopharyngeal carcinoma (NPC) who were treated with radiotherapy/concurrent chemoradiotherpy or concurrent chemoradiotherpy with adjuvant chemotherapy. Design: A retrospective review of case notes from the Kaohsiung Veterans General Hospital archives was performed. Setting: A medical centre in Taiwan. Participants: There were 145 newly diagnosed cases of NPC. Thirty‐nine patients were excluded because of the presence of distant metastasis at the time of presentation, loss of follow‐up and incomplete image information. Main outcome measures: Pearson’s chi‐square tests were used to analyse correlation between tumour invasion and prevetebral space involvement during univariate analysis and logistic regression was applied during multivariate analysis. Kaplan–Meier survival curves were constructed. Multivariate analysis was performed to examine the impact of various prognostic factors. Pearson’s chi‐square and Fisher’s exact test were also used to evaluate the correlation between failure patterns and treatment modality. Results: A total of 106 patients with newly diagnosed NPC were enrolled in this study. Forty‐three patients (41%) in this series were found to have prevertebral space involvement. Patients with prevertebral space involvement conferred a poor overall survival rate and metastasis‐free survival rate compared with those without prevertebral space invasion ( P = 0.04 and 0.02 respectively). Multivariate analysis showed that prevertebral space invasion was associated with an increased risk for distant metastasis [hazard ratio (HR) 14, 95% confidence interval (CI) 1.0–17.4; P = 0.03)] and overall survival (HR 7, 95% CI 1.1–135; P = 0.04). In patients with prevertebral space involvement, their metastasis‐free survival rate, with and without adjuvant chemotherapy, was 100% and 72.7% ( P = 0.047). This phenomenon was not observed in NPC patients without prevertebral space invasion. Conclusions: The present data revealed that prevertebral space involvement has a close relationship with survival rates and recurrence rates of patients with NPC. Nasopharyngeal carcinoma patients with prevertebral space involvement have more recurrence and poorer survival rates and should be the group to benefit from concurrent chemoradiotherapy followed by adjuvant chemotherapy. Inclusion of prevertebral space involvement may be needed to predict prognosis of NPC and help us to identify the high‐risk group.