Pathological Distribution of Positive Lymph Nodes in Patients with Clinically and Radiologically N0 Oropharyngeal Carcinoma: Implications for IMRT Treatment Planning

Background: We identified involved lymph node groups in patients with oropharyngeal carcinoma and radiologically N0 disease, aiming to define the clinical target volume, and to assess the negative predictive value of CT neck and correlate it to the tumor site, stage, and grade.

Methods And Materials: Between 1988 and 2000, we evaluated 53 patients who satisfied all of the following criteria: 1) oropharyngeal carcinoma diagnosis; 2) NO stage based on CT; 3) no prior treatment; and 4) primary surgical resection including ipsi-lateral neck dissection. The pathology reports were reviewed to identify the exact site of lymph node involvement.

Results: Twenty patients (37.7%) were found to have pathologically positive lymph nodes, yielding a negative predictive value of 62.3% for CT neck. Node levels II, III, and IV were the most commonly involved (26%, 17%, and 11% of all patients, respectively). Fifty percent of patients with T3 and T4 tumors had positive lymph nodes versus 20% of patients with T1 and T2 (P = 0.036). Tumor grade and site were insignificant (P > 0.05).

Discussion: Ipsilateral neck levels II-IV should be included during elective nodal irradiation in patients with N0-stage oropharyngeal carcinoma, regardless of the primary tumor site, stage, and grade.