Prognostic influence of prevertebral space involvement in nasopharyngeal carcinoma: a retrospective study

Abstract Purpose To evaluate how prevertebral space involvement (PSI) and degree of tumor extension within the space affects prognosis in nasopharyngeal carcinoma (NPC). Participants and Methods Data of patients with newly-diagnosed nonmetastatic NPC (n=757) were retrospectively analyzed. Patients were separated into groups according to presence or absence of PSI and degree of tumor spread. Overall survival (OS), failure-free survival (FFS), local relapse–free survival (LRFS), and distant metastasis–free survival (DMFS) were compared between the groups. Results Prevalence of PSI, simple prevertebral muscle involvement (PMI), and behind prevertebral muscle involvement (BPMI) were 44.9% (340/757), 22.5% (170/757), and 22.5% (170/757), respectively. OS, FFS, LRFS, and DMFS for patients with and without PSI were 64% vs. 84.8%, 68% vs. 85.6%, 85.8% vs. 94.4%, and 78.5% vs. 92.8%, respectively (all P 0.05). Conclusions PSI predicts poor prognosis in NPC. Survival is poorer in patients with BPMI than in those with simple PMI. NPC with PSI should be classified as T4 stage.