Prevalence of level V metastasis in head and neck squamous cell carcinoma

The results of this study accord with those of past reports about the prevalence of level V metastasis in head and neck squamous cell carcinoma (HNSCC) cases. Because of the low rate of level V metastasis, and from the viewpoint of standard postoperative radiotherapy, selective neck dissection without level V dissection may be possible in cases without clinical evidence of level V metastasis on both the ipsilateral and contralateral sides. In addition, degree of pathological differentiation and pN stage >N2b are suggested risk factors for level V metastasis.

The most frequent complication of any type of neck dissection in HNSCC cases with level V metastasis is shoulder dysfunction secondary to traction or ischemic injury to the spinal accessory nerve (SAN). The purpose of this study was to examine procedures to preserve the SAN and avoid level V dissection and shoulder dysfunction due to SAN injury. This study investigated the prevalence of level V metastasis and its associated risk factors at various primary sites in patients with HNSCC.

Clinical and pathological data were retrospectively reviewed for 162 patients with HNSCC, including those with clinically negative neck (cN0) and clinically positive neck (cN+) in whom level V neck dissection was performed. The prevalence of pathological metastasis to level V lymph nodes on both the ipsilateral and contralateral sides was investigated. Several potentially predictive risk factors for level V metastasis, such as age, sex, primary site, T stage, N stage, degree of pathological differentiation, and lymph node status of levels I-IV, were also evaluated. Statistical analysis was performed using Fisher's exact test.

In total, 301 neck dissections (ipsilateral side, n = 162; contralateral side, n = 139) were performed in this study. The most common primary site was the oral cavity (n = 51), followed by the larynx (n = 48), hypopharynx (n = 39), and oropharynx (n = 24). On the ipsilateral side, the overall incidence of pathologically positive neck (pN+) was 63.6% (103/162). The overall prevalence of level V metastasis was 7.4% (12/162), 6.8% (11/162) on the ipsilateral side, and 1.4% (2/139) on the contralateral side. Isolated level V metastasis and bilateral level V metastasis was observed in three patients and one patient, respectively. Metastasis to level V and other levels was observed in eight patients (8/96, 8.3%), and level V involvement on the ipsilateral side alone was observed only in three patients (3/66, 4.5%). There were two cases in which level V was involved when the other levels were also involved (2/22, 9.1%), and there was no case in which the other levels were not involved on the contralateral side. A statistically significant association was found between level V metastasis and pN stage >N2b (p = 0.0035), degree of pathological differentiation (p = 0.0305) on the ipsilateral side, status of neck levels I-IV (p = 0.001), and the number of positive neck levels (p < 0.0001) on the contralateral side.