Indications for and extent of elective neck dissection for lymph node metastasis from external auditory canal carcinoma.

[OBJECTIVES] We aim to clarify the frequency of lymph node metastasis of external auditory canal (EAC) carcinoma, including susceptible locations, adequate extent of elective neck dissection, and the relationship between the tumor infiltration site and lymph node metastasis.

[PATIENTS AND METHODS] From 2003 to 2018, 63 patients with EAC carcinoma at Tokyo Medical and Dental University Hospital were enrolled in this study. The T and N stages, locations of clinically positive lymph nodes, prognoses, and anatomic site of tumor infiltration were analyzed after treatment.

[RESULTS] Clinically positive lymph node metastasis (cN+) was detected in 18 patients (28.6%), consisting of T1, T2, T3, and T4 disease in 1 (6%), 2 (22%), 8 (38%), and 7 (41%) patients, respectively. The metastatic locations were at level II in 10 patients, parotid gland nodes in 7, preauricular nodes in 5, level Ib in 3, level Va in 3, level III in 1, and superficial cervical nodes in 1. Neck recurrence was determined in two of 45 patients with clinically negative lymph nodes (cN0), with the metastatic locations being levels II, Ib, and III. Among 18 cN+ cases, neck recurrence was noted in 2 of 9 patients who underwent neck dissection. Neck lesions were found to be manageable in all five patients who underwent docetaxel, cisplatin, 5-fluorouracil, and radiation therapy (TPF-RT). No relationship was noted between the tumor infiltration site and lymph node metastasis among T3/4 canrcinoma patients.

[CONCLUSIONS] Elective neck dissection could be indicated only in T3/4 patients with free flap reconstruction. Levels Ib to III are considered appropriate for elective neck dissection in cN0 cases. Levels Ib to III and Va indicated favorable sites, even in cases with metastasis in the parotid gland or preauricular area. Furthermore, TPF-RT could be a useful option even in cN+ cases.