Long-Term Outcomes of Additional Surgery After Endoscopic Resection Versus Primary Surgery for T1 Colorectal Cancer.

INTRODUCTION:There is considerable concern about whether endoscopic resection (ER) before additional surgery (AS) for T1 colorectal cancer (CRC) has oncologically potential adverse effects. Therefore, the aim of this study was to compare the long-term outcomes, including overall survival (OS), of patients treated with AS after ER vs primary surgery (PS) for T1 CRC using a propensity score-matched analysis from a large observational study. METHODS:This study investigated 6,105 patients with T1 CRC treated with either ER or surgical resection between 2009 and 2016 at 27 high-volume Japanese institutions, with those undergoing surgery alone included in the PS group and those undergoing AS after ER included in the AS group. Propensity score matching was used for long-term outcomes of mortality and recurrence analysis. RESULTS:After propensity score matching, 1,219 of 2,438 patients were identified in each group. The 5-year OS rates in the AS and PS groups were 97.1% and 96.0%, respectively (hazard ratio: 0.72, 95% confidence interval: 0.49-1.08), indicating the noninferiority of the AS group. Moreover, 32 patients (2.6%) in the AS group and 24 (2.0%) in the PS group had recurrences, with no significant difference between the 2 groups (odds ratio: 1.34, 95% confidence interval: 0.76-2.40, P = 0.344). DISCUSSION:ER before AS for T1 CRC had no adverse effect on patients' long-term outcomes, including the 5-year OS rate. ER is a viable first-line treatment option for endoscopically resectable T1 CRC.