Prognostic Value of Lymph Node Density in High-Grade Salivary Gland Cancers

BackgroundTo investigate the role of lymph node density (LND) as an independent prognostic factor in high-grade salivary gland cancers. MethodsAll 87 patients with high-grade salivary gland cancers underwent curative surgery combined with neck dissection and most of them received postoperative radiotherapy or chemoradiotherapy. LND was calculated as the ratio of positive lymph nodes to total lymph nodes harvested. Clinicopathologic variables associated with cancer-specific survival (CSS) and overall survival (OS) were identified by univariate and multivariate analyses using the Cox-proportional hazards model. ResultsSalivary duct carcinoma was the most common tumor (54%), followed by carcinoma ex pleomorphic adenoma (22%), and others. The 5-year CSS and OS were 50.9% and 49.6%, respectively, during a median follow-up of 61 months. In univariate analysis, tumor site, pathologic nodal stage, overall tumor-node-metastasis (TNM) stage, primary tumor size >3cm, lymphovascular invasion, perineural invasion, extranodal extension, number of metastatic lymph nodes, and LND >4.0 were significant prognostic factors for CSS and OS (P<0.05 each). Tumor site, perineural invasion, and LND were independent prognostic factors for both CSS and OS in multivariate analysis (P<0.01). ConclusionOur findings support the prognostic value of LND for high-grade salivary gland cancers. J. Surg. Oncol. 2015 111:784-789. (c) 2015 Wiley Periodicals, Inc.