Evaluation of gastric polyps in patients with upper gastrointestinal endoscopy

According to the study population, incidence of gastric polyps (GP) varies from 0.33% to 6.7% in various studies. Most GPs consist of proliferative polyps (HP), gastric fundus polyps (FGP) and adenomatous polyps (APs). Despite the high malignant AP potential, sporadic FGP has no malignant potential. On the contrary, HP has a lower risk of potential harm. It is not sufficient to perform biopsies to determine the presence of polyp types and displacements, therefore, some polyps may require extensive biopsy or complete resection.

In current study, GP frequency was low (0.38%), and HP frequency may be high due to high frequency of Helicobacter pylori (HPy) infection in China. Due to the high frequency of HPy infection and the short-term use of proton pump use, FGP frequency may be low.

Background
Polyps are usually asymptomatic and > 88% are detected by esophagogastroduodenoscopy for other reasons. Large polyps can cause bleeding, anemia, abdominal pain, or obstruction due to their position [1] . The diagnosis of polyps must be confirmed by histological examination [2] . The frequency of gastric polyps (GPs) and other polyps varies depending on the population under study [3] .
The prevalence of polyps is 0.6-6% [4] . Most polyps detected in the stomach are hyperplastic polyps (HPs), fundic gland polyps (FGPs) and adenomatous polyps (APs) [5] . HPs are most common in people with Helicobacter pylori infection [6] . In countries with low rates of H. pylori infection, FGPs are more common. The longterm use of proton pump inhibitors (PPIs) increases the frequency of FGPs [7] . The importance of GPs arises from the fact that some GPs have malignant potential or are associated with some hereditary syndromes. Although GPs appear in a number of congenital diseases, such as familial adenomatous polyposis, adolescent polyposis and Peutz-Jeghers syndrome, they are most commonly misdiagnosed [8] .There is an increased risk of cancer in polyps other than FGPs and inflammatory fibrinoid polyp (IFPs).In addition to FGP and polyps such as inflammatory fibrinoid polyp (IFP), the risk of cancer is increased with polyps. Although the risk of malignant transformation in HPs is low, it is more common in APs. Due to their 4 malignant potential and symptomatic nature, GPs are removed completely with endoscopic resection or surgery [9] .
In this study, our aim was to evaluate demographic, clinical, endoscopic, and histological data of patients with polyps or polypoid lesions. In addition, we evaluated diagnostic procedures, treatments and their complications, and the relationship between age and size and number of polyps.

Methods
At the Department of Gastroenterology, Shaanxi Hospital of Traditional Chinese Medicine, we retrospectively reviewed the results of 10000 consecutive esophagogastroduodenoscopy (EGD) procedures performed for various reasons between September 2017 and July 2019. Patients with GP or polyphenic lesions with polyps or malignant histology found by EGD were included in this study. We excluded patients who did not have polyps detected by biopsy, and those who had previously participated in the study but for whom we could not obtain pathological records. We evaluated age and sex; endoscopic indications and findings; GP count, size and location; histological diagnostic methods; and endoscopic treatment complications. The relationship between age and size and number of polyps was also assessed. The endoscope used was the Olympus EG 290 WR videoendoscope.
The size of the polyps was estimated by comparing it with the opening size of the biopsy forceps. In patients with multiple polyps, polyp diameter was calculated by measuring the largest polyp diameter.

Statistical Analysis
Data were analyzed using the SPSS software package program for Windows 23.0(SPSS, Chicago, IL, USA) . Descriptive statistics are used to describe continuous 5 variables. The χ2 (Fisher's exact) test was used to classify variables and expressed as the number of observations (and percentages). Statistical significance was obtained when the p value was <0.05. The Kolmogorov-Smirnov test was used to analyze the category data corresponding to the normal distribution, and Spearman correlation was used if the distribution of variables was abnormal.

Results
We included 1000 patients receiving EGD in our endoscopy unit. GPs were found in 384 patients, giving an incidence of 0.38%. None of the 74 patients who underwent polypectomy using forceps biopsy had complications, and only one patient had bleeding in the form of a leak during polypectomy and bleeding was controlled by sclerotherapy.

Discussion
We found that the most common symptoms of GPs were nausea, anemia and abdominal pain. We also found that GPs were mostly located in the abdominal anterior, and the most common type of histopathology was HP. GP incidence was 6.35% in 2645 EGD procedures [10] . The most common type of polyp was GFP, which accounted for 77% of all polyps, while HP and Foveolar hyperplasia FHP accounted for 17% of all polyps [11] . Sixteen percent of lesions defined as polyps did not have histopathological evidence of polyps or malignant histology. A previous study associated the high frequency of GFPs with long-term PPI use and low frequency of H. pylori infection [12] . In a previous study of 3024 endoscopic procedures, the most common type of polyp was HP [13,14] . The authors concluded that this may have been due to an increase in H. pylori infection [15] . GPs (1.4%) were reported in 36 patients, the most common type being HP, in 2657 EGD procedures [16] . In another study of 900 EGD procedures, GPs were found in 126 (1.4%) patients. Histological examination revealed 48 patients with HPs, 17 with GFPs, six with APs, and 118 had gastritis or normal histology [17] .
The most common type of polyp in our study was HP. The rate of H. pylori infection in China is 60-70% [18] . In countries with high frequency of H. pylori, the most common type of polyp is HP [19] . In a study of 3153 EGD procedures, 135 (4.3%) patients had polypoid lesions [20,21] . The average age of the patients was 65 years .
Polyp types were HP (52.3%), FGP (7.6%) and AP (3.5%). In addition, the incidence of adenocarcinoma was 1.8%. Histopathological examiniation of common mucosa showed that 29.7% of patients had polyps by EGD. A total of 153 patients (0.59%) were reported in 26 000 endoscopic procedures [22,23] . Among these patients, 41.2% were female and the average age was 64 years. The frequency of the different types of polyps was 72.4% HP, 17.2% FGP was 17.2%, and 11.8% AP. Adenocarcinoma was found in patients with HP or AP. In a study by Molaei et al, HP frequency was 69.2%, FGP was 6.6%, and AP was 4.7%. The average age of the patients was 49 years and 73% were male. In 87% of cases, polyp size was < 10 mm [24] . In a study by Fann et al, the mean age of patients was 54.7 years, 63% were female, and 37% were male [25] . In our study, ~80% of patients diagnosed with GPs were > 50 years old. There was no relationship between age and size and number of polyps. HPs and APs are commonly present in elderly people [26] . In our study, the incidence of GPs was 0.38%, which was lower than in most other studies. This may be due to patients who have been excluded because they had benign lesions or inappropriate polyp sampling. There have been few studies on GPs in China. In a study conducted by Gencosmanoglu et al, the incidence of GPs was 3.6%, and 48% of the polyps were HPs, 19% FHPs, and 17% FGPs [27] . The average age of the patients was 52 years and the proportion of women was 56.4%. In 57.2% of patients, polyp size was < 5 mm [28] . In a study by Karaman et al, 69 (0.59%) patients had a GP in 11 598 EGD procedures. Although 69% of polyps are HP, 10% are FGPs [29] . Buyukasik et al found that 66.7% of polyps were HPs in 55 887 EGD procedures [30] . Vatansever et al found that the incidence of GPs was 2.22%, and the highest frequency of HPs was 36.2% [31] . In our study, the most common type of polyp was HP. However, HP frequency was higher than in other studies. In addition, FGP frequency was significantly lower than in other studies. However, in a study conducted by Demiryilmaz et al, GPs were found in 66 (1.95%) patients in 3375 EGD procedures [32] . A total of 88 polyploid wound lesions were detected in these patients.
Histopathological examination of polyps showed that HPs accounted for 80.7%, inflammatory polyps 17%, and APs 2.3% [33] . FGP was not detected. In some studies, FGP was the most common type of polyp.
The frequency of polyps increases due to the frequency of H. pylori infection and increased use of PPIs . Many studies have shown an increase in the frequency of FGPs in patients using PPIs [34] . This relationship can cause anxiety among doctors and patients who need to use PPIs for a long time. In a study by Jalving et al, there was no increase in FGP frequency in patients using PPIs for < 1 year [35] . However, it has been found that long-term use of PPIs increases the risk of developing FGP fourfold. However, the risk of displacement did not increase. When subgroup analysis was performed, a significant increase in the risk of developing FGPs was observed in patients who had used PPIs for > 5 years. Patients with omeprazole and patients with other PPIs are at increased risk for developing FGPs due to long-term use of PPIs [7] . However, no increase in FGP frequency in patients using PPIs has been observed in some other studies [36] . A total of 30 347 H. pylori-negative patients were evaluated and FGP frequency was similar to that in 28 096 patients without PPIs and 2251 using PPIs, and PPI users had no increased risk of polyps [37] .
This may be due to short-term use of PPIs . In a study by Choudhry et al, patients with PPIs had the highest risk of developing FGPs after an average of 37 mo [38] .
Hongo et al prospectively studied the development of FGPs and HPs in patients with long-term PPI use, which was associated with an increase in GFP frequency in H.
pylori-negative patients. The formation of FGPs was not related to 11 hypergastrinemia.
However, HP development is associated with H. pylori infection and hypergastrinemia [39] . In our study, FGPs were found in eight patients. It is known that H. pylori infection reduces FGP formation, and these polyps are common in H.
pylori-negative patients . This low incidence may be related to high rates of H.
pylori infection in China. However, even in countries with high H. pylori infection rates, FGP frequency may be high, but these polyp have not been observed in several studies [40] . Frequency of FGPs is related to long-term PPI use. No increased risk of short-term use has been observed. The most common reason for EGD surgery is complaints of indigestion. The frequency of FGPs in our patients was low; probably because they had been treated with PPIs for a short time. Also, because these polyps are so small, they may be missed during EGD surgery or may be neglected due to their indistinct endoscopic appearance.
In our study, 20 (5.2%) patients had FHPs. These lesions are considered to be precursors of HPs, although it is unclear how long FHPs take to change to HPs. The lesions may be stable or may grow or shrink. However, whether they are HP precursors is still controversial. It has been shown that the basic structure and cytological criteria of FHPs and HPs can be easily distinguished by biopsy material obtained by endoscopic forceps. These lesions are not the result of HP precursors [41] . FHPs are common lesions in research. In our study, APs were detected in eight patients. Aps have been shown to account for 2.1% of GPs . These polyps are more common in patients with stomach cancer and have high malignant potential of 6.8-55.3% [42] . Lesion size, height of atypical hyperplasia and presence of intestinal epithelium are risk factors for malignant tumor development. Even adenomas with low displacement during long-term follow-up have malignant potential. Therefore, it is recommended to remove these lesions [26] . In addition, IFP was detected in one patient in our study. These polyps are not always diagnosed as endoscopic biopsies because they are local [33] . Because our case was not diagnosed by endoscopic biopsy, it was diagnosed after surgical removal [34] .
A total of 128 patients (33.3%) underwent snare polypectomy in our study. One patient required endoscopic control of bleeding. Low rates of hemorrhage caused by endoscopic polypectomy can be treated by sclerotherapy, endoclip or endoloop procedures. No death or penetration occurred in any patient. Snare polypectomy is a safe and effective way to diagnose and treat polyps.
In conclusion, the GP frequency in our study was low (0.38% and Ethics Committee approved the study, granted ethical approval, and all patients provided written informed consent to participate in this prospective study.

Consent for publication
Written informed consent was obtained from the patients and any accompanying images. Patients gave consent for their personal or clinical details along with any identifying images to be published in this study. all authors have read and approved the manuscrip.
All authors read and approved the final draft.