Abstract
Endoscopic resection (ER), especially endoscopic submucosal dissection (ESD), is a therapeutic technique as well as simultaneously an important diagnostic technique as total excisional biopsy. Histopathological complete resection of colorectal carcinoma (CRC) with negative horizontal and vertical margins is indispensable for curative resection. Currently, among the factors associated with curative resection based on the Japanese Society for Cancer of the Colon and Rectum (JSCCR) Guidelines 2014 for the Treatment of CRC, only the submucosal invasion depth of CRC can be diagnosed before ESD. Endoscopic ultrasonography is a useful modality for diagnosing resectable submucosal layer with negative vertical cut end directly. Even in patients with submucosal deep invasive (T1b) CRCs, the risk of lymph node metastasis is minimal under certain conditions. It was reported that the incidence of lymph node metastasis was only 1.3% when T1 (SM) CRCs met three of the JSCCR Guidelines 2014 criteria (i.e., all but invasion <1,000 μm). In addition, ER of T1 (SM) CRC did not worsen surgical and oncologic outcomes in cases that required subsequent surgery. Lymph node metastasis occurred in some patients with T1b CRC even if they had undergone surgical operation. In patients who have undergone radical ER of T1 (SM) CRC, physicians should consider whether additional surgical resection is necessary or not. Thus, even for T1b CRCs, ESD as total excisional biopsy can be suitable if complete en bloc resection is achieved. In the near future, it may be possible to identify T1 (SM) CRCs that can be cured with only ESD using some molecular pathologic markers, instead of conventional hematoxylin-eosin specimens.
