[Frequency and distributions of cervical lymph node metastases in oropharyngeal squamous cell carcinoma]

To examine the frequency and distribution of cervical lymph node metastases in oropharyngeal squamous cell carcinoma (SCC) and the necessities of prophylactic treatment of the neck.

We conducted a retrospective study of 242 patients with SCC of the oropharynx treated by surgery as the initial therapy at the National Cancer Center East Hospital from 1994 to 2008, excluding 53 patients who had local recurrences and 9 patients who had previously undergone neck dissection for metastasis from an unknown primary. We defined "potential lymph node metastases" as cases pathologically positive for lymph node metastases and/or secondary lymph node metastases and analyzed the necessity of prophylactic neck dissection for cases clinically negative for cervical metastases.

One hundred and eighty patients (148 males, 32 females) were included. The median age was 62 years (35 to 78). The clinical stages were Stage I in 20 patients, Stage II in 36 patients, Stage III in 39 patients, and Stage IV in 85 patients. In the ipsilateral neck of 70 patients at clinical stage N0, 15 patients (21.4%) were positive for potential lymph node metastases. There was no significant difference in the frequency of metastases by subsite. In terms of T classification, the positivity rates were 5.0% in patients at T1, 19.4% at T2, 44.4% at T3, and 60.0% at T4. In the contralateral neck of 70 patients at clinical stage N0, only 2 patients (2.9%) were positive for potential lymph node metastases. In the contralateral neck of 93 patients at clinical stage N1, N2a, or N2b (i.e., unilateral lymph node swelling), 16 patients (17.2%) were positive for potential lymph node metastases. The positivity rates by subsite were higher in patients with anterior, superior and posterior wall cancer than those with lateral wall cancer.

In the ipsilateral neck of patients at clinical stage N0, prophylactic neck dissection is not necessary for patients at T1 but necessary for those at T3 or T4. In the contralateral neck of such patients, prophylactic neck dissection is not recommended. In the contralateral neck of patients with unilateral lymph node swelling, prophylactic neck dissection is recommended for patients with anterior, superior or posterior wall cancer.