Neck level-specific nodal metastases in oropharyngeal cancer: is there a role for selective neck dissection after definitive radiation therapy?

Abstract

To determine the extent of the required neck dissection for patients with persistent lymphadenopathy after definitive radiation therapy for oropharyngeal cancer. If feasible, a conservative approach using selective neck dissection would likely minimize the extent of neck fibrosis and other adverse sequelae. Analysis of pretreatment and posttreatment radiologic scans and pathology reports of 76 patients with oropharyngeal carcinoma (35 tonsil; 41 base of tongue), who had radiologic evidence of persistent nodal disease for level-specific involvement. Patients were treated with twice-daily fractionations of external-beam radiation therapy (median dose, 76.8 Gy to the primary tumor) and planned neck dissection (levels I-V) for bulky nodes (N2-3) or salvage neck dissection for N1 disease. The distribution of clinical nodal disease by neck level on the basis of pretreatment and posttreatment radiologic scans indicated levels II and III to be most commonly involved. The false-negative rate for the restaging radiologic scans for each neck level was as follows: level I, 0%; level II, 8%; level III, 6%; level IV, 5%; and level V, 1.5%. Of the eight hemi-necks found to contain positive pathologic nodes in a neck level judged to be negative on the basis of restaging scans, five of the patients subsequently had disease recurrence in the primary site. Patients who had evidence of residual neck disease had a significantly lower rate of locoregional control (77% vs 100%, p =.0005). The extent of neck dissection for patients with nodal disease associated with oropharyngeal cancer treated with radiation therapy should include levels II-IV. It is reasonable to spare levels I and V in patients without radiologic and clinical evidence of positive nodes in levels I and V.