9.3 Indications

The indications of precutting EMR is as same as that of hybrid endoscopic submucosal dissection (ESD). However, tumor size is limited to 30–40 mm in precutting EMR. Treatment strategy for choosing between conventional EMR and precutting EMR should be discussed based on the clinicopathological characteristics of the lesions, endoscopist’ skill level, and patients’ condition.

9.4 Approach Strategy

A solution of indigo carmine in glycerin fructose is injected around the tumor to lift the submucosa. After circumferential mucosal incision using a ESD knife or a tip of snare, a mixture of glycerol and hyaluronic acid was injected into submucosal layer under the center part of the lesion prior to snaring. With regard to the conditions for performing precutting EMR, stable endoscopic operability of the lesion by the endoscopists is an essential requirement. The tip hood is not absolutely necessary in precutting EMR, because this technique has no procedure of submucosal dissection, although the tip hood makes it easier to conduct stable and safe incision of the surrounding normal mucosa. In addition, circumferential mucosal incision is not always necessary if the tumors can be resected by en bloc using a snare alone. However, a one-third circumferential mucosal incision was necessary to perform reliable histological en bloc resection. Hard-type snare is suitable for precutting EMR to prevent slip of the snare from the tumor. When the tumors have severe fibrosis in the submucosal layer, it is better to change the procedure submucosal dissection such as hybrid ESD or actual ESD.

9.5 Summary

The technical aspects of precutting EMR for colorectal tumors are outlined. This technique is expected to increase en bloc resection rate compared to conventional EMR. Precutting EMR is effective to reduce local recurrence due to high en bloc resection rate compared with conventional EMR. However, there a few reports concerning about the clinical usefulness of precutting EMR [5, 7, 8]. Lee et al. reported the treatment results of nonpedunculated colorectal tumors 20 mm or larger: the en bloc resection rates were 42.9% in the conventional EMR group, 65.2% in the precutting EMR group, and 92.7% in the ESD group, and the complete resection rates were 32.9% in the conventional EMR group, 59.4% in the precutting EMR group, and 87.6% in the ESD group [7]. Perforation occurred in 2.9% of the precutting EMR group and 8% of the ESD group, and local recurrence rates were 25.9% in the conventional EMR group, 3.2% in the precutting EMR group, and 0.8% in the ESD group [7]. Thus, precutting EMR is effective for relatively small lesions; however it shares the same limitations as conventional EMR. Precutting EMR for selected tumors that were difficult to resect en bloc through EMR due to their large size and difficult location. From the viewpoint of education, step-by-step use of precutting EMR is useful for less-experienced endoscopists with actual ESD [5]. When conventional EMR is difficult to perform, EMR with a small incision can be tried first, followed by hybrid ESD with circumferential mucosal incision and finally actual ESD.

In conclusion, precutting EMR is indicative for the colorectal tumors up to 30–40 mm in size, which is difficult to resect by en bloc using conventional EMR. This technique decrease local recurrence because of high en bloc resection rate.