Multicentric prospective study on the prevalence of sublevel IIb metastases in head and neck cancer.

OBJECTIVE: To evaluate the prevalence of sublevel IIB lymph node (LN) metastases for head and neck primary tumors in a large cohort of patients.
DESIGN: Prospective study.
SETTING: One referral university hospital and 2 national institutes of oncology. PATIENTS: Between 2003 and 2005, 297 patients (male to female ratio, 3.5:1; mean age, 58.8 years [range, 18-89 years]) affected by head and neck cancer were treated by surgery on the primary tumor and/or the neck. Primary site distribution included the following: oral cavity in 111 patients, larynx in 92, oropharynx in 32, thyroid gland in 22, skin of the lateral face or scalp in 16, hypopharynx in 11, unknown primary in 7, and parotid gland in 6. Sublevel IIB was evaluated for the number of LNs and pathologic N (pN) status.
INTERVENTIONS: All patients underwent unilateral or bilateral neck dissection (ND) with therapeutic or elective intent according to the primary site and clinical T (cT) and clinical N (cN) status. Sublevel IIB was selectively dissected at the beginning of ND, labeled, and processed independently. MAIN OUTCOME MEASURES: The distribution of metastases among the different levels was analyzed. The influence of several factors (institution in which the surgical procedure was performed, sex of the patient, site of primary, histotype, pathologic T [pT] status, cN status, lower level involved in the neck together with sublevel IIB, association with sublevel IIA metastasis, ipsilateral number of involved levels, and previous surgical treatment limited on the primary site) on the prevalence of sublevel IIB metastasis was statistically evaluated by the Pearson chi(2) test or Fisher exact test.
RESULTS: A total of 443 NDs were performed (unilateral in 151 patients and bilateral in 146). Among the patients, the tumors were staged cN0/pN0 in 27%, cN+/pN+ in 50%, cN+/pN0 in 7%, and cN0/pN+ in 16%. The mean number of LNs collected at sublevel IIB was 5.4 (range, 0-24). The overall prevalence of sublevel IIB metastases was 5.6% (26 neck sides). Tumor histologic type in the sublevel IIB+ population was squamous cell carcinoma in 80%, papillary carcinoma in 8%, melanoma in 8%, and adenocarcinoma in 4%. The chi(2) test showed a significantly higher risk for LN metastases at sublevel IIB in patients affected by parotid gland primary tumors (33%), tumors of the skin or scalp (25%), unknown primary tumors (14%), and cancers of the oral cavity (10%) (P = .02) and in those clinically staged as cN+ (P < .001).
CONCLUSIONS: Sublevel IIB dissection is strongly recommended for all patients with cN+ tumors and in those affected by tumor of the parotid gland, skin, and scalp scheduled for elective ND. Patients affected by laryngeal cancer scheduled for elective ND can be considered the ideal candidates for preservation of sublevel IIB. However, whether this policy could be associated with a better functional outcome remains to be demonstrated by prospective studies on a large series of patients.