Risk of metastatic recurrence after endoscopic resection for esophageal squamous cell carcinoma invading into the muscularis mucosa or submucosa: a multicenter retrospective study.

Background: We aimed to elucidate the risk of metastatic recurrence after endoscopic resection (ER) without additional treatment for esophageal squamous cell carcinomas (ESCCs) with tumor invasion into the muscularis mucosa (pT1a-MM) or submucosa (T1b-SM).
Methods: We retrospectively enrolled patients with pT1a-MM/pT1b-SM ESCC after ER at 21 institutions in Japan between 2006 and 2017. We compared metastatic recurrence between patients with and without additional treatment, stratified into category A (pT1a-MM with negative lymphovascular invasion [LVI] and vertical margin [VM]), B (tumor invasion into the submucosa ≤ 200 µm [pT1b-SM1] with negative LVI and VM), and C (others). Subsequently, using multivariate Cox analysis, we evaluated risk factors for metastatic recurrence after ER without additional treatment.
Results: We enrolled 593 patients, and metastatic recurrence occurred in 38 patients. Metastatic recurrence after additional treatment was significantly lower than that after no additional treatment in category C (9.1% vs. 23.6% in 5 years, p = 0.001), whereas no significant difference was noted in categories A (0.0% vs. 2.6%) and B (0.0% vs. 4.3%). In patients without additional treatment after ER, risk factors for metastatic recurrence were lymphatic invasion (hazard ratio [HR], 5.61), positive VM (HR, 4.55), and tumor invasion into the submucosa > 200 μm (HR, 3.25), and, but near half of the patients with metastatic recurrence had no further recurrence after salvage treatment, resulting in excellent 5-year disease-specific survival in categories A (99.6%) and B (100.0%).
Conclusions: Closed follow-up with no additional treatment may be an acceptable option after ER in pT1a-MM/pT1b-SM1 ESCC with negative LVI and VM.
(© 2021. Japanese Society of Gastroenterology.)