Pattern of Lymph Node Metastases and Its Implication for Radiotherapeutic Clinical Target Volume in Patients With cN0 Supraglottic Carcinoma: Ipsilateral or Bilateral Neck Irradiation

Abstract

To study the pattern of lymph node metastases (LNM) after laryngectomy and lymphadenectomy and clarify the clinical target volume (CTV) delineation of clinically LN negative (cN0) supraglottic squamous cell carcinoma (SSCC). Total cN0 211 SC patients who had undergone ipsilateral or bilateral II-III with or without IV level neck dissection according to the surgeon choice were retrospectively examined. The clinic-pathologic factors related to LNM were analyzed using logistic regression analysis. The median age of the whole group was 61.5y (41-82y), and most of patients (84.4%) were male. Forty-six patients (21.8%) had the lesions limited to one sides, 96 patients (45.5%) with asymmetric lesions across the midline, 69 patients (32.7%) with symmetric midline lesions. Most patients were stage T2 and T3 (38.4% and 43.1%). There were 142 patients (67.3%) receiving bilateral neck dissection (BND), 69 patients in ipsilateral neck dissection (IND). Totally, 219 (62.0%) II-IV level neck dissection were administrated, 134 (38.0%) with II-III neck dissection. Thirty-four patients (16.1%) received postoperative treatment according to the NCCN guidelines. The median number of lymph node dissection were 22 (10-53) and 45 (16-117) in the IND and BND group. Occult LNM was present in 46 patients (21.8%). Contralateral LNM were found in 8/142 patients (5.6%) in BND group, which all these 8 patients had bilateral LNM. The contralateral LN failure was found in only 1/69 patients (1.5%) after the median follow up of 46 months in IND group. The most common LNM were found in level II (41 in all 353 neck dissection, 11.6%), followed by level III (25/353, 7.1%), and level IV (4 in 219 neck dissection including level IV, 1.8%). The isolated level IV LNM was found in only 1 patients (0.5%). The poor histological differentiation was statistically significant risk factors of LNM (P < 0.008). Ipsilateral level II-IV irradiation is recommended in cN0 SSCC patients with pathological high and moderate differentiation. Contralateral level II-III irradiation may be considered in poor differentiation. However, the possible LNM side of the midline lesions need to be studied in future.