351. CONVERSION SURGERY FOR PATIENTS WITH ESOPHAGEAL CANCER AFTER ICI TREATMENT

Abstract Background As more and more immuno checkpoint inhibitor (ICI) agents are used in clinical practice for the treatment of esophageal cancer these days, we are becoming more likely to see a patient with initially unresectable but currently resectable tumor through the treatment with ICIs. Little is known about such conversion surgery for esophageal cancer. So, we here report our experiences. Subjects and Methods The patients who underwent esophageal cancer surgery after the treatment with ICI from 2020 to 2023 who had initially been diagnosed as unresectable were enrolled. Electronic medical records were retrospectively reviewed to collect clinicopathological findings. Result There were 15 eligible cases; 12 male and 3 female, median age 70 (51-81). Histology was SCC in all cases; 7 primary, 7 recurrent and 1 residual tumors. Involved distant metastatic organ was lymph node in 4 cases, liver in 4 cases, and lung in 1 case. Involved recurrent organ was lymph node in all the 7 recurrent cases. Clinical response to ICI treatment was detected in 12 cases (PD in 3 cases). R0 resection was achieved in 14 cases and pCR was detected in 3 cases. No irAE-suspected event was detected in all cases during postoperative course. Conclusion Since the patients' background, number and duration of the ICI treatment, treatment history before the conversion surgery were miscellaneous, it is still hard to lead conclusive statement on the conversion surgery for esophageal cancer after ICI treatment. So, it is necessary to keep going to experience conversion surgery cases for esophageal cancer to assess its efficacy.