Long-Term Outcomes After Endoscopic Submucosal Dissection for T1 Colorectal Cancer: A Multicenter Prospective Study

BACKGROUND & AIMS: Prospective evidence for the long-term efficacy of endoscopic submucosal dissection (ESD) for T1 colorectal cancer (CRC) is lacking. We evaluated the long-term outcomes after ESD for T1 CRC, focusing on risk stratification and the benefits of additional surgery. METHODS: This large-scale, multicenter, prospective cohort study, conducted by Hiroshima GI Endoscopy Research Group, included consecutive patients with pathologically confirmed T1 CRC who underwent colorectal ESD between 2014 and 2018. Patients were classified into low- and high-risk groups per Japanese Society for Colorectal Cancer Research guidelines. High-risk patients either underwent additional surgery (surgery group) or were followed without surgery (follow-up group). The primary outcome was the 5-year cumulative recurrence rate. RESULTS: Among 2358 patients who underwent ESD for 2478 early colorectal neoplasms, 383 patients with T1 CRC were enrolled. Ten recurrences (3.6%) and 5 T1 CRC-associated deaths (1.8%) occurred in the high-risk group; none occurred in the low-risk group. Five-year cumulative local recurrence rate in the high-risk group was significantly higher in the follow-up group than in the surgery group (6.8% vs 0%; P < .001), whereas distant recurrence did not differ significantly (2.7% vs 1.9%; P = .704). Five-year overall survival in the high-risk group was significantly worse in the follow-up group than in the surgery group (79.7% vs 95.2%; P < .001), whereas 5-year disease-specific survival was similar (98.4% vs 98.5%; P = .420). CONCLUSIONS: ESD alone appears appropriate for low-risk T1 CRC, with no recurrence or disease-specific mortality observed, suggesting that intensive surveillance is unnecessary after curative ESD. In high-risk T1 CRC, additional surgery could prevent local recurrence; however, its impact on distant metastasis and disease-specific survival remains unclear. TRIAL REGISTRATION NUMBER: UMIN000016197.