[Prophylactic neck dissection for submandibular gland cancer].

The indication and preferred dissection field for prophylactic neck dissection for submandibular gland cancer are controversial and have not been standardized. We reviewed 27 patients who underwent a definitive operation for previously untreated submandibular gland cancer. The 27 patients consisted of 13 patients with adenoid cystic carcinoma, 6 patients with mucoepidermoid carcinoma, 6 patients with adenocarcinoma, and 2 patients with squamous cell carcinoma. The diagnostic accuracies of malignancy and histology with fine needle aspiration cytology were 86% and 56%, respectively. In sixteen out of 21 cases without neck lymph node metastasis, a prophylactic neck dissection was performed and pathological neck lymph node metastases were detected in five cases. On the other hand, in five cases that did not receive a prophylactic neck dissection, latent neck lymph node metastasis was observed in 2 cases. In both cases of neck lymph node metastasis, pathological positive lymph nodes were observed in only level 2 or level 3. The rates of occult neck lymph node metastasis according to the T stage were 0% in T1, 33.3% in T2, 57.1% in T3 and 100% in T4. The rates of occult neck lymph node metastasis according to the histopathology were 46.2% in adenoid cystic carcinoma, 50% in mucoepidermoid carcinoma, 50% in adenocarcinoma, and 50% in squamous cell carcinoma. In conclusion, we believe that supraomyohoid neck dissection is suitable for N0 cases of submandibular gland cancer because of four reasons: 1) rate of occult neck lymph node metastasis in submandibular gland cancer is high, 2) pathological neck lymph node metastasis in N0 cases and latent neck lymph node metastasis were observed in level 2 and level 3, 3) the prognosis of cases with neck lymph node metastasis was poor, and 4) same skin incision can be used not only for the primary resection but also for the neck dissection.