Endoscopic submucosal dissection (ESD) has been at the forefront of international attention as a less invasive treatment for early gastrointestinal cancer. Currently, ESD involves the use of an electrosurgical knife for mucosal incision and subsequent submucosal dissection. However, it has been reported that perforation occurs in approximately 5% of cases. To enhance tissue selectivity with this modality, we focused on applying a laser to ESD (laser ESD). A CO2 laser was chosen as the surgical knife because the saline or sodium hyaluronate solution injected into the submucosal layer during the current ESD procedure has a high absorption coefficient at the wavelength of the CO2 laser. Thus, the purpose of this study is to quantitatively clarify the safety and efficacy of laser ESD for the colon. First, we validated a porcine colon as a model of the human colon in terms of optical and thermal properties. Next, ex vivo experiments on the safety and efficacy of laser ESD were performed. In ex vivo experiments using extracted porcine colon tissue, an incision depth of 0.5-1.0 mm was obtained without thermal damage to the muscle layer when the power density was set at 17, 22, or 28 W/mm2. In addition, less thermal damage was observed in tissue incised with this method compared with electrosurgical knives. These results might be explained by the strong absorption of the CO2 laser by the saline injected into the submucosa. Therefore, laser ESD is expected to be a safer method for the treatment of early colon cancer.
Keywords: Carbon dioxide laser; Colon cancer; Endoscopic submucosal dissection; Laser absorber; Perforation; Thermal damage.