Patterns of regional spread and the value of elective neck treatment for oral mucosal melanoma

Objective To investigate the patterns of regional lymphatic spread and the value of elective neck treatment (ENT) in oral mucosal melanoma (OMM). Methods In this retrospective analysis, 61 OMM patients with no distant metastasis treated in Cancer Hospital of Chinese Academy of Medical Sciences between 1984 and 2016 were recruitred. The regional lymph node distribution of cN+ disease, the value of ENT in cN0 disease, the failure patterns and prognostic factors were retrospectively analyzed. Results Overall, 55.7% of the patients were clinical/pathological cN+. The most frequently involved locations were the level Ⅰ b (76%), followed by level Ⅱ and level Ⅲ. For cN0 patients, the 5-year regional failure-free survival rate was 91.7% in patients who received at least ipsilateral level Ⅰ b-Ⅲ ENT and 52.4% in patients who did not receive at least ipsilateral level Ⅰ b-Ⅲ ENT (P=0.036). The regional failure rate was 6% for patients treated with at least ipsilateral leve Ⅰ b-Ⅲ ENT, while in their counterparts who did not receive at least ipsilateral level Ⅰ b-Ⅲ ENT was 46%(P=0.035). For the regional failure pattern, the most frequently failure sites were level Ⅰ b (93%), level Ⅱ(50%) and level Ⅲ(36%). Conclusions The cervical lymph node metastasis rate is relatively high in OMM patients. The pathway of regional LN spread follows a regular pattern. The most frequently involved regions for clinical/pathological cN+ and regional failure are both level Ⅰ b-Ⅲ. Elective treatment including at least ipsilateral level Ⅰ b-Ⅲ ENT should be recommended for OMM patients with cN0.