Neck dissection field and lymph node density predict prognosis in patients with oral cavity cancer and pathological node metastases treated with adjuvant therapy.

Pathological lymph node metastases (pN+) are an established prognostic factor in oral cavity squamous cell carcinoma (OSCC). We retrospectively examined the prognostic significance of lymph node (LN) density in pN+ OSCC patients who underwent neck dissection (ND) and postoperative adjuvant therapy. We examined 309 pN+ patients who underwent levels I-III ND and 148 pN+ patients treated with levels I-V ND. The 5-year control and survival rates served as the main outcome measures. The 5-year rates for patients treated with levels I-III and I-V NDs were as follows: local control, 79%, 74% (p=0.0630); neck control, 81%, 68% (p=0.0014); distant metastasis, 21%, 36% (p=0.0003); disease-free survival (DFS), 59%, 43% (p=0.0001); disease-specific survival (DSS), 66%, 46% (p<0.0001); and overall survival (OS), 49%, 37% (p=0.0048), respectively. Multivariate analysis demonstrated that an LN density ≥0.16 was an independent prognostic factor for 5-year neck control (all data presented as p, hazard ratio [95% confidence interval]) (0.003, 2.691 [1.412-5.128]), distant metastases (0.001, 2.831 [1.520-5.270]), DFS (<0.001, 2.464 [1.571-3.866]), and DSS (0.036, 1.781 [1.040-3.052]) in levels I-III ND patients. An LN density ≥0.048 was an independent predictor of 5-year local control (0.004, 4.871 [1.654-14.344]), neck control (0.002, 24.738 [3.367-181.771]), DFS (<0.001, 4.151 [2.264-7.610]), DSS (<0.001, 3.791 [2.017-7.125]), and OS (<0.001, 2.806 [1.706-4.613]) in levels I-V ND patients. Our findings demonstrate the prognostic value of LN density for guiding treatment strategies in OSCC patients who are to receive adjuvant therapy.