A feasibility and dosimetric evaluation of endoscopic radiofrequency ablation for human colonic and rectal epithelium in a treat and resect trial

Background Endoscopic radiofrequency ablation (RFA) has been used effectively for ablation of foregut disorders and also may have a role in treating colonic pathology. This study aimed to assess the feasibility of delivering RFA to locations within the colon and to determine a range of safe treatment parameters. Methods Patients undergoing left hemicolectomy or proctocolectomy were evaluated. Focal RFA using a colonoscope-mounted device was delivered to normal segments of the colon and rectum within the planned surgical resection specimen. Endoscopic accessibility and feasibility of delivering heat energy to the colon and rectum were assessed as well as the maximum incurred histologic depth of ablation in relation to the number of applications (2 or 4) and the energy density (12, 15, or 20 J/cm²). Results A total of 51 ablation zones in 16 patients had available histopathology. None of the sites receiving two applications demonstrated serosal layer alteration compared with 15% of the sites receiving four applications (p = 0.11). Muscularis propria alterations were seen in 25% of the two-application sites and 63% of the fourapplication sites (p < 0.05). Increasing energy density from 12 to 20 J/cm² did not correlate with a deeper ablation effect. Conclusions Endoscopic RFA is capable of delivering therapy to the distal colon. Injury is limited to the muscularis propria or less depth when no more than two ablations are applied regardless of the energy density used. Based on these feasibility and dosimetry results, the authors will continue investigation using these and smaller energy doses to initiate trials ultimately with patients who have suitable mucosal and submucosal disorders of the lower gastrointestinal tract including chronic, nonulcerated hemorrhagic radiation proctitis and angiodyplasia.