Relationship between the growth pattern of nasopharyngeal cancer and the cervical lymph nodes based on MRI findings: Can the cervical radiation field be reduced in patients with nasopharyngeal cancer?

To identify patients with nasopharyngeal cancer in whom the cervical radiation field can be reduced, we classified the growth patterns of nasopharyngeal cancer based on MRI findings into 4 types and performed an evaluation. Based on MRI findings, we classified the growth patterns of primary cancer in 94 patients with nasopharyngeal cancer into Type 1 (superficial type), Type 2 (lateral invasive type), Type 3 (upward invasive type), and Type 4 (anterior extension type), and further classified Type 2, based upon nasopharyngoscopic findings, into Type 2a (unilateral invasive type) and Type 2b (bilateral invasive type). The cervical lymph node metastasis areas were evaluated according to these types. Type 2 showed a significantly higher incidence of cervical lymph node metastasis only on the ipsilateral side than the other types (p=0.0024). in particular, all patients with Type 2a had cervical lymph node metastasis only on the ipsilateral side (p=0.0212). This study suggests that the distribution of metastasised cervical lymph nodes depends on the pattern of tumour extent of the primary site.