With the advancement of endoscopic resection(ER)of colorectal cancer, surgical resection after ER has been increasing. This study evaluated the effects of initial ER on short- and long-term outcomes in T1b colorectal cancer. This retrospective cohort study enrolled patients with pathological T1b colorectal cancer who underwent colorectal surgical resection between 2008 and 2018. A total of 239 eligible patients were divided into 2 groups: patients initially treated using surgical resection with lymph node dissection(LND)(surgery alone, n=142)and patients treated using initial ER and additional surgical resection with LND(surgery after ER, n=97). No significant differences were observed in short-term outcomes(ie, operative time, blood loss, or postoperative complications)or the long-term outcomes(ie, recurrence rate, overall survival rate, or recurrence free survival rate)between groups.