RESUMO
Objective To evaluate the prognostic impact of MRI-detected prevertebral space involvement in nasopharyngeal carcinoma (NPC) treated with radiotherapy and chemotherapy.Methods A retrospective analysis was performed on the clinical data of 333 patients who had newly diagnosed biopsyproven NPC without distant metastasis from 2005 to 2007.All patients underwent MRI scans of the nasopharynx and neck and were treated with two-and three-dimensional radiotherapy without or without chemotherapy.The Kaplan-Meier method was used to calculate overall survival (OS),distant metastasis-free survival (DMFS),and locoregional relapse-free survival (LRFS),and the log-rank test was used for survival difference analysis;the Cox proportional hazards regression analysis was used to assess the prognostic value of prevertebral space involvement.Results The follow-up rate was 95.2％.Prevertebral space involvement was seen in 139(41.7％) of these patients.The patients with prevertebral space involvement had significantly higher T stage and clinical stage than those without prevertebral space involvement (x2 =90.41,P =0.000;x2 =54.03,P =0.000).The 5-year OS,DMFS,and LRFS for NPC patients with and without prevertebral space involvement were 58.8％ vs.77.5％ (x2 =11.95,P =0.000),77.8％ vs.85.0％(x2=2.56,P=0.110),and 88.3％ vs.91.8％ (x2=1.51,P=0.220),respectively.After adjusting for N stage,a significant difference was still seen between the two groups with regard to 5-year OS (x2 =9.93,P =0.002).The multivariate analysis showed that prevertebral space involvement was not the independent prognostic factor for OS,DMFS,and LRFS (x2 =0.43,P =0.512 ; x2 =0.08,P =0.783 ; x2 =0.00,P =0.971).Conclusions The frequency of prevertebral space involvement is very high in NPC.The OS for the patients with prevertebral space involvement is significantly lower than those without prevertebral space involvement.But prevertebral space involvement is not the independent prognostic factor in NPC patients.