539. ASSOCIATION BETWEEN WAITING PERIOD FOR RADICAL SURGERY AND POSTOPERATIVE RELAPSE IN CLINICAL STAGE I ESOPHAGEAL CANCER

Background Esophagectomy with locolegional lymphanedectomy based on potential lymph node metastatic risk is the current standard treatment for clinical Stage I thoracic esophageal cancer. Local excision by endoscopic submucosal dissection (ESD) is the standard treatment for clinical Stage 0, however surgery is considered as an additional treatment for pathological T1b cases due to potential metastatic risk. Cases of additional resection after ESD are those pathologically demonstrated to have a high risk of metastasis based on tumor depth and vascular invasion, etc. Compared to cases of surgery for clinical Stage I, many of these cases have a high risk of metastasis, and therefore a poor prognosis is generally expected. Addionally, the prolonged waiting time between initial diagnosis and radical surgery due to ESD may be a factor in poor prognosis, but there is currently no consensus on the risk. Therefore, we conducted a study to clarify the effect of waiting period before surgery (WP) on the risk of recurrence in clinical Stage I esophageal cancer surgery. Methods We retrospectively evaluated the association between WP and 3-year postoperative recurrence-free survival (3y-RFS) in 65 patients who underwent primary esophagectomy and gastric tube reconstruction for clinical Stage I esophageal cancer and 22 patients who underwent additional resection after ESD at our hospital. Results The WP of 87 patients was 2.12 ± 1.43 months (mean± SD), and 13 patients had postoperative recurrence (3y-RFS 85.1%). A 2-arm comparison of short or long WP with a cutoff value of 2.83 months (mean+0.5 SD) showed no clear association with 3y-RFS (100% vs 81.4%, p=0.071). A strong correlation was shown between WP and ESD (r=0.647, p<0.01). WP was 1.69±1.20 months (mean± SD) in 65 patients who underwent surgery as initial treatment, and 12 patients had postoperative recurrence (3y-RFS 81.5%). A 2-arm comparison of short or long WP with a cutoff value of 2.29 months (mean+0.5 SD) suggested an association with 3y-RFS (85.7% vs 55.6%, p=0.018). Conclusion Although this is a single-center, retrospective study of a small number of cases and only a univariate study due to the small number of events, it suggests that a longer waiting period before surgery may be a risk factor for postoperative recurrence.