PS02.203: CHARACTERISTICS AND RISK FACTORS OF LYMPH NODE METASTASIS IN ESOPHAGEAL SQUAMOUS CELL CARCINOMA PATIENTS WITH PREOPERATIVE COMPUTED TOMOGRAPHY-NEGATIVE LYMPH NODES

Background Characteristics and risk factors of lymph node metastasis (LNM) in esophageal squamous cell carcinoma (ESCC) patients with preoperative computed tomography (CT)-negative lymph nodes are not well elucidated. This study aimed to identify the characteristics and risk factors of LNM in ESCC patients with preoperative CT-negative lymph nodes. Methods We conducted a retrospective analysis of consecutive ESCC patients who had preoperative CT-negative lymph nodes and received esophagectomies between August 2013 and July 2016. Lymph node with a short-axis diameter ≦10 mm on preoperative CT image was considered as CT-negative lymph node. Eligible patients included those: aged 18∼80, without neoadjuvant therapy, without other malignant tumor history, without distant metastasis, without multiple esophageal lesions, tumor locating in the thoracic esophagus, receiving McKeown esophagectomy, undergoing R0 resection, having number of lymph nodes resection≧15, pathological staging as T1a-4aN0–3. Univariate and multivariate logistic regression analyses were used to identify risk factors of LNM. Results Among 243 ESCC patients identified, 137 had LNM (56.4%). The median number of lymph nodes dissected and LNM were 24 (range 15–79) and 2 (range 1–14), respectively. The rates of LNM of the upper, middle and lower thoracic ESCC were 50.0%, 59.3% and 55.1%, respectively. The rates of LNM with the maximal short-axis diameter of lymph node on preoperative CT of ≦5 mm, 6 mm, 7 mm, 8 mm, 9 mm and 10 mm were 57.4%, 42.9%, 47.4%, 31.8%, 73.9% and 70.8%, respectively (P = 0.034). Univariate analysis showed that age (P = 0.041), maximal short-axis diameter of lymph node on CT (P = 0.034), cervical lymph node dissection (P = 0.031), lymphovascular invasion (P < 0.001) and perineural invasion (P = 0.017) were associated with LNM. Multivariate analysis revealed that cervical lymph node dissection (P = 0.018), lymphovascular invasion (P = 0.007) and perineural invasion (P = 0.025) were independent risk factors of LNM. Conclusion Our study showed that the rates of LNM were also high in ESCC patients with preoperative CT-negative lymph nodes. Standard lymph node dissection is necessary for these patients. Cervical lymph node dissection, lymphovascular invasion and perineural invasion are independent risk factors of LNM in ESCC patients with preoperative CT-negative lymph nodes. Disclosure All authors have declared no conflicts of interest.