Radiofrequency Ablation and Photodynamic Therapies: What Are the In-Vivo EUS and Histologic Correlates?

Abstract

Tissue vaporization or coagulation from PDT and balloon-based radiofrequency (RF) ablation has been gaining acceptance as a potential treatment for Barrett esophagus and local esophageal adenocarcinoma. However, there is a paucity of data regarding the extent of epithelial changes secondary to these forms of ablative therapy. Aim: To determine EUS and histologic changes in human esophageal epithelium subsequent to PDT and RF treatments. Methods: Prospective EUS examinations and systematic biopsies in four quadrants, each cm, and at set time intervals were performed following treatment of Barrett esophagus with PDT or RF. Energy was delivered at 200 J/cm for PDT, whereas the RF energy density was pre-set at 12 J/cm2. All patients were placed on PPI's. Results: 55 patients (51 men, 4 women), mean age 68 (38-81), underwent PDT or RF from 11-2003 to 12-2005. The length of Barrett segments ranged from 1 cm to 10 cm. Eleven patients had histologically proven and verified high grade and were treated with RF. A total of 44 EUS examinations with mechanical radial, electronic radial, electronic linear echoendoscopes and through-the-scope probes were performed in 6 PDT and 4 RF patients. Biopsies were obtained in 4 quadrants every cm with jumbo forceps. Post PDT changes affected the mucosa, submucosa, and muscularis propria with thickness up to 8 mm, which decreased to 3.4 mm @ month 19. RT changes included the muscularis propria with thickness of 4 mm @ month 9. One patient in each group developed adenocarcinoma at 8 and 9 months. The longest post ablative EUS follow-up was 19 months. Conclusions: Ablative therapy with PDT and RF can cause epithelial changes through the muscularis propria. The predominant alterations are seen as hypoechoic thickening of the mucosal and submucosal layers. The increased thickness lessens with time. EUS hypoechoic thickening of the mucosa, submucosa, and muscularis propria without endoscopically visible nodule/mass is likely non-malignant in this clinical setting.