Background and objective: The level-Ib lymph node metastasis is rare in nasopharyngeal carcinoma (NPC). When and how this level should be irradiated with precise radiotherapy remains controversial. This study evaluated the prevalence and prognostic significance of level-Ib lymphadenopathy on the prognosis of NPC patients.
Methods: From January 1990 and December 1999, 933 newly diagnosed patients with NPC treated at Sun Yat-sen University Cancer Center were randomly selected, examined with computed tomography (CT) imagining for evidence of level-Ib lymphadenopathy before treatment. All patients received radical radiotherapy with or without chemotherapy. The relationship between level-Ib lymphadenopathy and post-treatment outcomes including overall survival (OS), locoregional recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were analyzed using Kaplan-Meier methods. The Cox proportional hazards regression model was used to adjust for other prognostic factors.
Results: Of the 933 patients, 55 (5.9%) were found to have level-Ib lymphadenopathy, which was associated with carotid sheath involvement, oropharynx involvement and levels, and lateral cervical lymph node involvement. In the subgroup with carotid sheath involvement, with multivariate analysis accounting for all previously known prognostic factors, level-Ib lymphadenopathy was still associated with a risk of decreased OS (RR, 2.124; P<0.001), DMFS (RR, 2.168; P<0.001), and LRFS (RR, 1.989; P=0.001).
Conclusion: Level-Ib lymphadenopathy in the patients with carotid sheath involvement is an independent prognostic factor.