Novel beagle model of gastric local fibrotic target lesions for the evaluation and training of endoscopic techniques

BACKGROUND

Novel endoscopic techniques used in the treatment of gastric lesions with local submucosal fibrosis need preclinical evaluation and training due to safety limitations. Therefore, the purpose of our study was to establish an animal model of gastric local fibrotic target lesions and assess its feasibility in the evaluation and training of endoscopic techniques.

METHODS

In six experimental beagles, a 50% glucose solution was injected into three submucosal areas of the fundus, body, and antrum of the stomach to create gastric local fibrotic target lesions (experimental group). On post-injection day (PID) 7, the injection sites were assessed endoscopically to confirm the presence of submucosal fibrosis formation, and the dental floss clip traction assisted endoscopic submucosal dissection (DFC-ESD) procedure was performed on the gastric local fibrotic target lesions to confirm its feasibility after endoscopic observation. The normal gastric mucosa of six control beagles underwent the same procedure (control group). All the resected specimens were evaluated by histological examination.

RESULTS

All 12 beagles survived without postoperative adverse events. On PID 7, 16 ulcer changes were observed at the injection sites (16/18) under the endoscope, and endoscopic ultrasonography confirmed the local submucosal fibrosis formation in all ulcer lesions. The subsequent DFC-ESD was successfully performed on the 32 gastric target lesions, and the mean submucosal dissection time in the ulcer lesions was greater than that in the normal gastric mucosa (15.3 ± 5.6 vs. 6.8 ± 0.8 min; P < 0.001). There was no difference in rates of en bloc resection, severe hemorrhage, or perforation between the two groups. Histological analysis of the ulcer lesions showed the absence of epithelial or muscularis mucosae and extensive submucosal fibrous tissue proliferations compared with normal gastric mucosa. Overall, endoscopists had high satisfaction with the realism and feasibility of the animal model.

CONCLUSION

We developed a novel animal model of gastric local fibrotic target lesions to simulate difficult clinical situations, which strongly appeared to be suitable for the preclinical evaluation and learning of advanced endoscopic techniques.

Variation in colectomy rates for benign polyp and colorectal cancer

BACKGROUND

Removal of pre-cancerous polyps on screening colonoscopy is a mainstay of colorectal cancer (CRC) prevention. Complex polyps may require surgical removal with colectomy, an operation with a 17% morbidity and 1.5% mortality rate. Recently, advanced endoscopic techniques have allowed some patients with complex polyps to avoid the morbidity of colectomy. However, the rate of colectomy for benign polyp in the United States is unclear, and variation in this rate across geographic regions has not been studied. We compared regional variation in colectomy rates for CRC versus benign polyp.

METHODS

We performed a retrospective population-based study of Medicare beneficiaries undergoing colectomy for CRC or benign polyp, using the 100% Medicare Provider Analysis and Review files from 2010 to 2015. We used multivariable linear regression to obtain population-based colectomy rates for CRC and benign polyp at the hospital referral region (HRR) level, adjusted for age, sex, and race.

RESULTS

Of 280,815 patients, 157,802 (65.8%) underwent colectomy for CRC compared to 81,937 (34.2%) for benign polyp. Across HRRs, colectomy rates varied 5.8-fold for cancer (0.32-1.84 per 1000 beneficiaries). However, there was a 69-fold variation for benign polyp (0.01-0.69). While the rate of colectomy for CRC was correlated with the rate of colectomy for benign polyp (slope = 0.61, 95% CI 0.48-0.75), HRRs with the lowest or highest rates of colectomy for CRC did not necessarily have similarly low or high rates for benign polyp.

CONCLUSIONS

The use of colectomy for benign polyp is much more variable compared to CRC, suggesting overuse of colectomy for benign polyp in some regions. This variation may stem from provider-level differences, such as endoscopists' referral practice or skill or surgeons' decision to perform colectomy, or from limited access to advanced endoscopists. Interventions to increase endoscopic resection of benign polyps may spare some patients the morbidity and cost of surgery.