Metastatic pathways and lymph node dissection in lower lip cancer

The most common histologic entity among lower lip neoplasms is squamous cell carcinoma (SCC). Nodal metastasis is found in approximately 8% of patients, a figure which lies between the dissemination prevalence rates of cutaneous (4-5%) and oral SCC (20-40%). The submental and submandibular lymph nodes (level IaEuroa and IaEurob) are most often involved, and nodal metastases are found with decreasing frequency in the cervical nodes of levels II, III and IV along the jugular and carotid sheath. The risk for nodal dissemination rises with increasing tumor depth and dedifferentiation (histologic grading), factors which can be combined to identify patients with a higher risk for nodal metastases. Further risk factors are tumor size, immunosuppression, perineural spread, lymph vessel invasion, and frequent tumor recurrence. In patients with a higher risk for nodal metastases elective lymph node surgery/dissection (ELND) should be considered, even if staging shows no evidence for dissemination (cN0). Selective lymph node dissection (SLND) of level I and II (suprahyoidal SLND) or level I-III (supraomohyoidal SLND) are adequate in cN0 cases. Extension to further levels or modified radical neck dissection is only necessary when metastases are present. Alternatively, sentinel lymph node biopsy (SLNB) can be performed, although adequate evidence-based data on SLNB are currently unavailable. Lymph node surgery in lip cancer can be performed together with resection of the primary tumor and lip reconstruction, or later in a secondary procedure.