Endoscopic resection alone as a potential treatment method for low-risk deep invasive T1 colorectal cancer

Abstract

Background and AimsAlthough T1b (deep submucosal invasion) is described as an indication of surgical resection with lymph node dissection for T1 colorectal cancer (CRC) in current guidelines, it has been reported to be a weaker correlation to the lymph node metastasis (LNM) than other risk factors (lymphovascular invasion, poorly differentiated or mucinous adenocarcinoma, tumor budding). “Low-risk T1b” CRC, which is defined as a lesion with only T1b and no other risk factors, may not require additional surgical resection. This study aimed to evaluate the necessity of surgeries in patients with low-risk T1b CRC from the point of the risk of LNM, recurrence and long-term outcome. MethodsFrom April 2001 to March 2019, 1,271 T1 CRCs were resected. Invasion depth and tumor budding were diagnosed according to the Japanese guideline, lymphovascular invasion was evaluated with special staining and immunostaining, and histological grade was diagnosed by the highest differentiation. Then, we analyzed 354 patients with low-risk T1b CRC. Among these, 105 patients were resected endoscopically without surgical resection (ER-alone group) and 249 patients were resected surgically (SR group). We examined the rate of LNM, the cumulative recurrence, and overall survival (OS) in each group. ResultsNo LNM was observed in both ER-alone group (0% (95%CI, 0-4.2%)) and SR group (0% (95% CI, 0-1.8%)). Five-year cumulative recurrence rate was 0% (95%CI, 0-9%) in ER-alone group and 0% (95% CI, 0-3%) in SR group. Five-year OS rate was 93% (95%CI, 90-96%) in ER-alone group and 95% (95% CI, 93-96%) in the SR group (p = 0.35). ConclusionsER alone without SR could be a potential treatment method for patients with low-risk T1b CRC.