The volume to be irradiated during selective neck irradiation in nasopharyngeal carcinoma: analysis of the spread patterns in lymph nodes by magnetic resonance imaging

BACKGROUND: For this report, the authors analyzed the spread pattern of lymph node (LN) metastases in patients with nasopharyngeal carcinoma (NPC) by using magnetic resonance imaging (MRI). In addition, the efficacy of selective neck irradiation was assessed based on the volume irradiated. METHODS: This was a retrospective review of data from 924 patients with newly diagnosed and nondisseminated NPC who underwent MRI and treatment between January 2003 and December 2004. RESULTS: According to the criteria for involved LNs detected by MRI, the incidence of LN metastases was 85.1% (786 of 924 patients). An analysis of the distribution of LN metastases in these 786 patients demonstrated that the retropharyngeal LNs (RLN) and Level II LNs were the most frequently involved regions, followed in order by Level III and Level V LNs, Level IV LNs, and supraclavicular fossa (SCF) LNs. In only 4 of 786 patients (0.5%) did metastasis skip LNs in their progression. In addition, 5 of 354 patients (1.4%) who had unilateral, higher level LN metastases (including RLNs and Level II LNs) had contralateral or bilateral, lower level LN involvement (including Level III, Level IV, Level V, and SCF LNs). In patients who had LN-negative (N0) disease, the risks of regional recurrence and distant metastasis did not differ statistically between patients with inferior border of the neck irradiation field either at the cricoid cartilage or below the cricoid cartilage. CONCLUSIONS: By using MRI, LN metastases spread in an orderly fashion from higher level LNs to lower level LNs. The current results did not support prophylactic irradiation of Level IV and SCF LNs in patients who were negative for LN metastases, and these concepts need to be tested clinically before they may be recommended generally. Cancer 2009. © 2008 American Cancer Society.