Risk of Metastasis and Local Residual Cancer After Non‐Curative Endoscopic Submucosal Dissection for Esophageal Cancer

ABSTRACT Background Endoscopic submucosal dissection (ESD) is widely used to treat early‐stage esophageal squamous cell carcinoma (SCC). However, the risk of recurrence in non‐curative cases remains uncertain. This study aimed to elucidate the risk of local and metastatic recurrence of esophageal SCC treated with ESD. Methods We retrospectively analyzed data for 222 patients who underwent ESD followed by esophagectomy and fulfilled the following criteria: (1) no metastatic lesions diagnosed before ESD and (2) pathologically diagnosed SCC with SM invasion regardless of VM status or pathologically diagnosed SCC with lymphovascular invasion. The primary outcome was the proportion of metastasis and local residual cancer determined using the pathological findings of additional esophagectomy specimens and follow‐up data. Results For submucosal cancer with positive lymphovascular invasion, the metastasis rate was 29.5% (23/78) compared with 8.8% (5/57) in submucosal cancers with negative lymphovascular invasion. The metastasis rate for vertical margin (VM) 1 or VMX was 30.8% (16/52) compared with 20.7% (28/135) in submucosal cancer. Local residual cancer was observed in 10 (19.2%) individuals with VM1/X, with 80% of these involving the submucosal layer ( n = 4) and muscularis propria or deeper ( n = 4). Among cases with VM0, local residual cancer was observed in six (3.5%) individuals, of which 66.7% were mucosal cancers. Conclusions In conclusion, the proportions of metastasis and local residual cancer in non‐curative cases were clarified. While additional treatment is necessary to reduce these risks, if a patient is managed with observation alone, strict surveillance that accounts for these risks is required.