256. PROGNOSIS AND RISK FACTORS FOR SUPRACLAVICULAR LYMPH NODE METASTASIS IN PATIENTS WITH MIDDLE AND LOWER THORACIC ESOPHAGEAL CANCER

Abstract Background Whether supraclavicular lymph node metastases (#104 LNM) in patients with thoracic esophageal cancer are classified as distant or regional metastases differs between Western countries and East Asia. Therefore, in Japan, 3FL is a standard procedure, but in Western countries, 3FL may be rarely practiced. We aimed to determine the frequency and prognosis of #104 LNM compared with other regional LN stations and to identify risk factors for #104 LNM in patients with advanced thoracic esophageal cancer to investigate value of treatment of #104 LNM. Methods The study cohort of 567 eligible patients with esophageal cancer had undergone subtotal esophagectomy radically from 2003 to 2020. LN metastasis was defined as pathologically proven metastasis or positron emission tomography positive LNs. The effectiveness of LN dissection was assessed using an efficacy index (EI) that we calculated by multiplying the rate of metastasis (%) to each LN station by the 5-year overall survival (OS) rate of each patient and then dividing by 100. In order to clarify the indication for 3FL, risk factors for #104 LNM were determined by multivariable logistic regression. Results Among of 567 patients, 66 (11.6%) had #104 LNM. #104 LNM occurred in 31.7%, 10.7%, and 5.6% of patients with upper, middle, and lower thoracic lesions respectively. All patients had squamous cell carcinoma. Neoadjuvant chemotherapy was administered to 71% of patients, and chemo-radiation to 11%. The 5-year OS was 45.8%. The EI for #104 LNs (5.3) was like that for #101 LNs. Risk factors were age <65 years, upper lesion, clinical stage N2–3, and #101/106rec LNM. When assessing only middle and lower lesions, the 5-year OS of patients was 38% (EI 3.1), similar to that for #101 and #8/9/11 LNs, with similar risk factors to overall population. Conclusions The EI of patients with #104 LNM was similar to that of patients with other regional LNM such as #101 and #8/9/11 LNs, Therefore, patients with #104LNM were worth treated LN dissection. However, we recommend 3FL exclusively for patients with #104 LNM or those at high risk of metastasis due to the overall metastatic rate not being high.