Radiofrequency ablation for the treatment of gastric dysplasia: a pilot experience in three patients

Role of submucosal injection in radiofrequency ablation of gastric low-grade dysplasia: Effects on symptoms and outcomes

BACKGROUND

To date, there is still a lack of standardized management strategies for gastric low-grade dysplasia (LGD), which is a direct neoplastic precancerous lesion and requires specifically superficial destruction. Radiofrequency ablation (RFA) is expected to be an effective method for gastric LGD, but post-RFA pain may affect patients' satisfaction and compliance. The current study aimed to evaluate the value of a submucosal injection prior to RFA (SI-RFA) for postoperative pain and treatment outcomes.

METHODS

Between October 2014 and July 2021, gastric LGDs without risk factors (size >2 cm, unclear boundary, and abnormal microsurface and microvascularity) undergoing regular RFA and SI-RFA were retrospectively analyzed. Postoperative pain scores, wound healing, and clinical efficacy were compared. Propensity score matching, stratified analysis, and multivariable logistic regression were performed to control the confounding variables.

RESULTS

One hundred and ninety-seven gastric LGDs in 151 patients received regular RFA. Forty-nine gastric LGDs in 36 patients received SI-RFA. Thirty-six pairs of patients were selected for the assessment of postoperative pain by propensity score matching. Compared to regular RFA, SI-RFA significantly decreased the degree and duration of postoperative pain (OR, 0.32; 95% CI, 0.13-0.84; P = 0.020), improved wound healing rate (80.0% [36/45] vs. 58.9% [89/151], P = 0.012), increased the complete ablation rate (91.8% [45/49] vs. 86.3% [170/197], χ2 = 1.094, P = 0.295), but correlated with higher rates of local recurrence and progression (25.6% [10/39] vs. 13.2% [18/136], χ2 = 3.471, P = 0.062; 8.3% [3/36] vs. 0.9% [1/116], P = 0.042). The multivariable logistic regression model confirmed that submucosal injection was associated with local recurrence (OR, 2.93; 95% CI, 1.13-7.58; P = 0.027).

CONCLUSIONS

Submucosal injections prior to RFA may reduce postoperative pain and scar formation while ensuring complete ablation of gastric LGD. However, local recurrence and progression should be considered seriously.

Comparison of Endoscopic Radiofrequency Ablation and Argon Plasma Coagulation in Patients with Gastric Low-Grade Intraepithelial Neoplasia: A Large-Scale Retrospective Study

BACKGROUND

Gastric low-grade intraepithelial neoplasia (LGIN) is a precancerous lesion of gastric cancer. Endoscopic therapies represented by radiofrequency ablation (RFA) and argon plasma coagulation (APC) have been applied to treat gastric LGIN in recent years. However, no comparative study examining the effectiveness and safety profiles of RFA and APC has been reported.

METHODS

A single-center, large-scale, retrospective study, including 73 and 50 patients treated with RFA and APC, respectively, was conducted in the First Medical Center of Chinese PLA General Hospital from October 2015 to October 2020, with a two-year follow-up. Effectiveness, complications, operative factors, and other data were assessed.

RESULTS

At 2 years of follow-up, cure, relapse, recurrence, and progression rates were 90.4%, 9.6%, 9.6%, and 2.7% in the RFA group, respectively, versus 90%, 10%, 12%, and 4% in the APC group, respectively, with no statistically significant differences between the two groups (all p > 0.05). However, the mean lesion size was significantly larger in the RFA group (2.6 ± 1.0 cm) than in the APC group (1.5 ± 0.6 cm) (p < 0.001); there was also a significant difference in the composition ratio of large lesions between the two groups (p < 0.001). No serious postoperative complications showed in either group, and the abdominal pain was the most common symptom in the short term after surgery.

CONCLUSIONS

RFA and APC are both safe and effective destructive therapies for gastric LGIN. RFA is more suitable for flat and large lesions, while APC is more suitable for small lesions, especially those with slight local uplift or depression. An intraoperative submucosal injection is expected to be an effective method for relieving postoperative abdominal pain.

Clinical efficacy and prognostic risk factors of endoscopic radiofrequency ablation for gastric low-grade intraepithelial neoplasia

BACKGROUND

The use of radiofrequency ablation (RFA) has been reported in the treatment of gastric low-grade intraepithelial neoplasia (LGIN). However, its efficacy and prognostic risk factors have not been well analyzed.

AIM

To explore the efficacy and prognostic risk factors of RFA for gastric LGIN in a large, long-term follow-up clinical study.

METHODS

The clinical data of 271 consecutive cases from 198 patients who received RFA for treatment of gastric LGIN at the Chinese PLA General Hospital from October 2014 to October 2020 were reviewed in this retrospective study. Data on operative parameters, complications, and follow-up outcomes including curative rates were recorded and analyzed.

RESULTS

The curative rates of endoscopic RFA for gastric LGIN at 3 mo, 6 mo, and 1-5 years after the operation were 93.3%, 92.8%, 91.5%, 90.3%, 88.5%, 85.7%, and 83.3%, respectively. Multivariate analyses revealed that Helicobacter pylori (H. pylori) infection and disease duration > 1 year had a significant effect on the curative rate (P < 0.001 and P = 0.013, respectively). None of patients had bleeding, perforation, infection, or other serious complications after RFA, and the main discomfort was postoperative abdominal pain.

CONCLUSION

RFA was safe and effective for gastric LGIN during long-term follow-up. H. pylori infection and disease course > 1 year may be the main risk factors for relapse of LGIN after RFA.

Gastric intestinal metaplasia: when to treat? How to treat?

PURPOSE OF REVIEW

Gastric intestinal metaplasia (GIM) is an attractive target for surveillance and treatment as it can progress to gastric adenocarcinoma (GAC). Yet, GIM remains a challenging area for clinicians as most patients do not progress to cancer, and there are conflicting data regarding the benefits of surveillance and therapy. This review aims to summarize recently published GIM surveillance guidelines, to discuss, which patients with GIM may benefit from treatment, and to review pivotal and recent literature on GIM therapy.

RECENT FINDINGS

Guidelines published by American, British, and European gastroenterology societies do not recommend universal surveillance, but do suggest endoscopic surveillance in patients with risk factors for progression to GAC. Although light examination for at least 7 min and mapping biopsies may increase yield for dysplasia and GAC. In randomized trials, Helicobacter pylori eradication reduced risk of dysplasia and cancer. In GIM with visible dysplasia and early-stage GAC, endoscopic resection improves quality of life without reducing survival compared with surgery. Endoscopic ablation therapies have shown promise for invisible or extensive dysplasia.

SUMMARY

Endoscopic resection is appropriate for visible dysplasia and early-stage GAC without high-risk features that persists despite H. pylori eradication therapy. Prospective studies are needed to assess the utility of endoscopic ablation in GIM.

Modular laser-based endoluminal ablation of the gastrointestinal tract: in vivo dose-effect evaluation and predictive numerical model

BACKGROUND

Endoscopic submucosal dissection allows for "en bloc" removal of early gastrointestinal neoplasms. However, it is technically demanding and time-consuming. Alternatives could rely on energy-based techniques. We aimed to evaluate a predictive numerical model of thermal damage to preoperatively define optimal laser settings allowing for a controlled ablation down to the submucosa, and the ability of confocal endomicroscopy to provide damage information.

MATERIALS AND METHODS

A Nd:YAG laser was applied onto the gastric mucosa of 21 Wistar rats on 10 spots (total 210). Power settings ranging from 0.5 to 2.5W were applied during 1-12 s, with a consequent energy delivery varying from 0.5 to 30 J. Out of the 210 samples, a total of 1050 hematoxilin-eosin stained slides were obtained. To evaluate thermal injury, the ratio between the damage depth (DD) over the mucosa and the submucosa thickness (T) was calculated. Effective and safe ablation was considered for a DD/T ratio ≤ 1 (only mucosal and submucosal damage). Confocal endomicroscopy was performed before and after ablation. A numerical model, using human physical properties, was developed to predict thermal damage.

RESULTS

No full-thickness perforations were detected. On histology, the DD/T ratio at 0.5 J was 0.57 ± 0.21, significantly lower when compared to energies ranging from 15 J (a DD/T ratio = 1.2 ± 0.3; p < 0.001) until 30 J (a DD/T ratio = 1.33 ± 0.31; p < 0.001). Safe mucosal and submucosal ablations were achieved applying energy between 4 and 12 J, never impairing the muscularis propria. Confocal endomicroscopy showed a distorted gland architecture. The predicted damage depth demonstrated a significant positive linear correlation with the experimental data (Pearson's r 0.85; 95% CI 0.66-0.94).

CONCLUSIONS

Low-power settings achieved effective and safe mucosal and submucosal ablation. The numerical model allowed for an accurate prediction of the ablated layers. Confocal endomicroscopy provided real-time thermal damage visualization. Further studies on larger animal models are required.

Effects of Nd:YAG laser for the controlled and localized treatment of early gastrointestinal tumors: Preliminary in vivo study

Endoscopic submucosal dissection (ESD) is a minimally invasive technique allowing for the removal of early gastrointestinal (GI) tumors, widely considered as a valid alternative to conventional surgery. However, ESD is technically demanding, and potentially severe complications, such as bleeding and perforation, may occur. Energy-based techniques (e.g., radiofrequency ablation) might offer a potential alternative to ESD. However, their use mandates the ability to predict the damage induced and to identify a "signature" of the complete ablation, without the need for a physical specimen. Ideally, an energy-based procedure should be tunable in order to limit the ablation to the superficial layers, namely mucosa (M) and submucosa (SM), without injuring the muscularis propria (MP), thereby minimizing GI perforation. This experimental study aims to investigate thermal damage induced by Nd:YAG laser on the gastric wall, at different laser settings such as power (P) and time (t). Laser ablation was performed on the stomach wall of 6 Wistar rats. Two powers (2.5W and 1.0W) and 3 exposure times (12s, 6s and 2s) were tested, for a total of 30 ablations. Histological analysis allowed to assess thermal damage, in terms of damage depth (DD) and identification of involved layers. The ratio (R) between DD and the total depth (TD) of target layers (M+SM) was used as an index to evaluate the effectiveness of laser settings. At P=2.5W, MP was damaged (R>1) in the majority of cases (11/15). At P=1.0W, MP was preserved in all tests (R<;1), and rarely (4/15) did the damage reach the whole SM (R=1). Histopathological analysis evidenced that tissue damage was strongly related to the variable tissue thickness. These preliminary results seem to support the fact that endoscopic tunable laser ablation is feasible with a consistent damage/power correlation. Further tests are required to optimize the settings for applications on early GI tumors.

Emerging indications of endoscopic radiofrequency ablation

INTRODUCTION

Radiofrequency ablation (RFA) is a well-validated treatment of dysplastic Barrett's esophagus. Other indications of endoscopic RFA are under evaluation.

RESULTS

Four prospective studies (total 69 patients) have shown that RFA achieved complete remission of early esophageal squamous intra-epithelial neoplasia at a rate of 80%, but with a substantial risk of stricture. In the setting of gastric antral vascular ectasia, two prospective monocenter studies, and a retrospective multicenter study, (total 51 patients), suggest that RFA is efficacious in terms of reducing transfusion dependency. In the setting of chronic hemorrhagic radiation proctopathy, a prospective monocenter study and a retrospective multicenter study (total 56 patients) suggest that RFA is an efficient treatment. A retrospective comparative study (64 patients) suggests that RFA improves stents patency in malignant biliary strictures.

CONCLUSIONS

Endoscopic RFA is an upcoming treatment modality in early esophageal squamous intra-epithelial neoplasia, as well as in gastric, rectal, and biliary diseases.