It has been recognized that promotion of endoscopic screening is important to improve the diagnosis rate of EGC[10]. Many studies have also provided suggestions on how to improve the accuracy and effectiveness of detecting EGC[11,12]. In recent years Well-qualified endoscopic screening has began to become available in China,as a result more EGCs have been found and treated with ER[13,14]. We investigated the clinical data and endoscopic findings of EGC treated with ESD in our center,and compared the characteristics of EGC in different gastric parts in order to elucidate their own particular features of the lesions according to anatomical sites,which will be much beneficial for us to diagnose and treat EGC more efficaciously and accurately afterwards. In this study we especially focused on EGC at gastric angle as its particular anatomy. This is also the first report to characterize EGC at the gastric angle treated with ESD[15].
In our case series we found that the gastric angle was the second most common location of EGCs treated by ESD,accounting for twenty-three percent of all patients.The gastric angle is a bending area on the lesser curvature, comprising the boundary between the gastric body and the antrum. Although it is a small area ,there is a high percentage of gastric diseases such as gastric ulcer and cancer arising from this region in Chinese patients.Most studies reported the distributions of gastric cancer according to the lower third, middle third, and upper third of the stomach.Feng et al.[16]reported that EGC lesions were found 318 patients(63.2%) in the lower third, 98 patients (19.5%) in the middle third, and 87 patients (17.3%)in the upper third of the stomach respectively in 503 patients of Chinese ethnicity. However,we believe that it is better to evaluate the distributions of EGC according to gastric antrum,angle,body, fundus,and cardia,which would be more helpful to our targeted endoscopic observation of different parts, and improve the early diagnostic efficiency of early gastric cancer. Therefore, as to a second common site of EGC,we should pay more attention to observing gastric angle region endoscopically.
With a more detailed investigation on the EGC features at the different anatomical regions where EGC occurs, we found there were higher rates of larger lesions in size at gastric angle and body,and a higher rate of flat-depressed lesions at gastric angle according to endoscopic gross type. It was also unexpectedly noticed that severe submucosal fibrosis was more commonly found in the lesions of EGC located at the gastric angle than those at other gastric parts during ESD procedure. In our opinion it may be the reasonable explanations for this result that gastric ulcers are prone to occur at the gastric angle region and there is the higher rate of flat-depressed EGC lesions at gastric angle .Oi et al[17] have put forward the double-regulation theory to explain why peptic ulcer disease often occured in the gastric angle and why the ulcer often recurs at the same or adjacent parts of previous ulcers. Mechanical tension and exposure to high concentrations of acid in the pyloric gland area may lead to these findings. Ulcer recurrence may lead to the abnormalities of the scar and severe submucosal fibrosis In result of repeated ulcer healings. Furthermore, in addition to more flat -depressed EGC lesions at the gastric angle, in our study we also found that more ulcerative lesions were observed in the severe submucosal fibrosis group at the gastric angle. Isozaki et al.[18] reported that the depressed EGC lesions with ulcer can lead to the severe submucosal fibrosis that occurs in the submucosa of EGC lesions,which sometimes can be misdiagnosed as advanced gastric cancer.
It has been considered that the location of EGC lesions at the gastric angle was one site of difficult ESD because the submucosal dissection plane at the gastric angle is much difficult to manipulate.Furthermore severe submucosal fibrosis also imposes great difficulty for endoscopic submucosal dissection because submucosal injections normally fail to raise the lesion[19], leading to a higher non-en bloc resection rate, a longer procedure time and higher risk of perferation in our study.In addition, Nagata et al[20] reported that the density of fibrotic changes in the lesion affects ESD procedure time. Therefore,a challenge lies in cleaving fibrotic submucosal tissue beneath scars(severe submucosal fibrosis to achieve higher en bloc resection rate and lower procedure time,as well as avoid perforation. Traction-assisted endoscopic submucosal dissection using dental floss and a clip has been reported to be useful for shortening the duration of the ESD procedure and reducing the risk of intraoperative perforation, which would be more helpful for managing the lesions with severe submucosal fibrosis ,especially for the lesions located at the gastric angle[21].
Some reports have suggested that severe submucosal fibrosis is a risk factor of microperforation during ESD[22].When fibrosis is present beneath the lesion, the thin submucosal cushion due to lifting failure and hard fibrotic tissue probably lead to surgical error through improper positioning of the knife. Though the patients have microperforations, surgical treatment can be avoided by immediately closing the hole with endoclips. The rapid closure of openings minimizes gastric content leaks. A recent result suggests that the small size of the defect in patients with microperforations after closure and the low level of bacterial contamination from the gastric contents due to gastric acidity prevented contamination of the peritoneal cavity and reduced the need for nasogastric drainage[23].
Our study has several limitations. First, it was a retrospective study in a single academic center. The data from multicenter and prospective studies may be more accurate for research. In addition, this retrospective study didn’t include patients who underwent surgical resection or untreated patients with EGC. Therefore, because of its retrospective nature and selection bias, the data in this study cannot be generalized. Second, because of the small number of patients with severe submucosal fibrosis at the gastric angle, multivariate analysis for determining independent predictors of severe submucosal fibrosis was not performed.