PS02.187: RELATIONSHIP BETWEEN REGIONAL LYMPH NODE SIZE AND PROGNOSIS IN ESOPHAGEAL CANCER PATIENTS

Background Surgery for esophageal cancer, in many cases performed after chemotherapy or chemoradiotherapy. Because treatment policy is determined by pretreatment evaluation, improvement of diagnosis accuracy is important. Commonly, metastatic diagnosis is performed by uniformly defining the size. We examined whether evaluation of N classification reflecting more prognosis can be done by examining lymph node metastasis criteria by area in CT. Methods We surveyed 300 cases of thoracic esophageal cancer (squamous cell carcinoma) who underwent surgery at our hospital from September 2010 to December 2014. We defined lymph node with a minor axis of 5 mm or more from CT (5 mm slice) before treatment as ‘visible node’. We changed the cut off of lymph node short diameter for each area to 5 mm, 10 mm and 15 mm, and those with long diameter/short diameter ratio less than 1.5 were designated as ‘metastasis’. We examined the optimal size of lymph node which reflect prognosis. We compared the correlation with the prognosis based on the N category of the 8th edition UICC TNM classification and the 11th edition Japanese Classification of Esophageal Cancer, using the cutoff of short diameter examined for each area. Results We evaluated the cut off of each area lymph node except paraesophageal, 15 mm in the cervical, 10 mm in the recurrent nerve, 15 mm in the upper trachea, 15 mm in the lower trachea, and 10 mm in the epigastric. Classification based on the N classification of the 8th edition UICC TNM classification, overall survival declined in the order of N categories. Conclusion From this result, it was suggested that diagnosis based on lymph node size in CT reflects prognosis by prescribing cut off for each site. From now on, it would be possible to raise the diagnostic accuracy of N classification further by subdivision of cut off and accumulation of the case. Disclosure All authors have declared no conflicts of interest.