555. SUPRACLAVICULAR NODE INVOLVEMENT, A NODAL OR METASTATIC DISEASE? - A 10-YEAR EXPERIENCE IN ESOPHAGEAL CARCINOMA AT A TERTIARY REFERRAL CENTRE

Abstract Background Despite the advance in neoadjuvant chemothepray/chemoradiotherapy and favourable outcomes of surgical management in supraclavicular lymph node (SCLN) involvement reported in recent studies, the latest AJCC/UICC TMN classification still regards SCLN metastasis as extra-regional i.e Stage IVB (M1) disease. The role of SCLN dissection and surgical management remain controversial. At National University Hospital of the present study, bilateral supraclavicular lymphadenectomy is routinely performed for resectable thoracic ESCC. The aim of this retrospective cohort study is to investigate the long-term outcome of surgical management in pathological SCLN metastasis and its survival benefit comparing to Stage IIB-IVA diseases. Methods Patients with ESCC who underwent esophagectomy and 3-field lymphadenectomy with curative intent between January 2013 and January 2023 at the single centre were included; cases of salvage esophagectomy post-definitive concurrent chemoradiotherapy, palliative resections, and concurrent head and neck cancers were excluded. Neoadjuvant treatments were considered in cases staged clinically as T2 and/or N1 or greater. Pathological status of lymph nodes was recorded according to JES classification. Demographics and prognostic factors were examined using univariant analysis of overall survival (OS). Patients with SCLN metastases and other LN involvements were compared and OS were analysed using Kaplan-Meier method. Results 544 patients were included. 183 had one or more pathological LN metastasis (pN1:126, pN2 46, and PN3: 11) in which 55 patients had SCLN metastasis. Patients with LN metastasis had poorer prognosis than those without (pN0) with a Hazard Ratio (HR) of 2.68 (95% CI, 1.12-3.40, p<0.01); similar pattern was seen in patients with SCLN metastasis (HR 2.28, p<0.01). The 3-year and 5-year OS of patients with SCLN metastasis was 18.5% and 11.6% respectively whereas those of other LN metastasis was 21.4% and 15.8%; the difference between the groups was not statistically significant (p=0.525) (graph 1). Conclusion Lymph node status (pN) is a well-recognised prognostic factor as reaffirmed, however, within the pN positive cohort, long-term survival of patients with SCLN metastasis, considered as stage IVB (M1), was comparable (p<0.05) to those with other LN metastases. This supports the survival benefit of surgical resection with neoadjuvant therapy in SCLN metastases as following nodal disease treatment algorithm; further evaluation including systemic therapy and lymph node sub-group analysis is being conducted. Whilst randomised controlled trials such as Japanese JCOG2013 provides level I evidence, the present study provides complementary real-world experience for SCLN dissection.