Recently, the American Society for Gastrointestinal Endoscopy (ASGE) conducted a comprehensive evaluation of previous studies and developed clinical guidelines for the “Endoscopic Management of Gastric Cancer and Precancerous Lesions,” which were published in a recent issue of GastrointestEndosc.
Pre-cancerous lesions of the stomach
Gastric polyps
(1) Sporadic gastric epithelial polyps
Endoscopic changes cannot be used to distinguish the histologic classification of gastric polyps; therefore, biopsy should be performed when polyps are found endoscopically. Studies have shown that the vast majority of gastric epithelial polyps are fundic gland polyps (FGPs) or hyperplastic polyps. Sporadic FGPs may be associated with long-term use of proton pump inhibitors, but the risk of cancer is not increased in patients with non-familial adenomatous polyposis (FAP) who present with FGPs.
In contrast, hyperplastic polyps are associated with an increased risk of gastric cancer. Heterogeneous hyperplasia and malignancy can be found in 5-19% of patients with hyperplastic polyps, so guidelines in some countries recommend resection of hyperplastic polyps larger than 0.5-1 cm in diameter. Numerous studies have shown that hyperplastic polyps larger than 1 cm in diameter and tipped hyperplastic polyps are risk factors for heterogeneous hyperplasia.
In addition, adenomatous polyps have the potential to develop into malignant tumors. Gastric adenomatous polyps should be resected endoscopically when circumstances permit, but follow-up of postoperative patients has shown that recurrence rates can reach 2.6% and 1.3% of patients develop gastric cancer. Compared to EMR, endoscopic submucosal resection reduced tumor recurrence but increased the incidence of other adverse events.
Endoscopy should be performed one year after adenomatous polypectomy and every 3-5 years thereafter. Hyperplastic and adenomatous polyps may develop in the setting of HP infection and environmental sexualized atrophic gastritis and should be excised at this time.
(2) Gastric polyps in FAP and Lynch syndrome
Gastric polyps are common in individuals with FAP, with the most common gastric polyps being FGPs, seen in 88% of children and adults with FAP. Adenomas can also occur in patients with gastric FAP and are often solitary, fixed and located in the gastric sinus. In addition, gastric adenocarcinoma associated with FGPs often occurs in patients with familial polyposis syndrome. However, data on the risk of gastric cancer in patients with FAP and Lynch syndrome vary from country to country and even contradict each other.
Gastrointestinal epithelial metaplasia and heterogeneous hyperplasia
Studies have shown that patients with gastrointestinal epithelial metaplasia (GIM), a precancerous lesion that may be associated with HP infection, smoking and a high-salt diet, have a 10-fold higher risk of developing gastric cancer than the normal population. Two UK studies found that the incidence of gastric cancer among GIM patients was as high as 11%, and endoscopic surveillance can help with early detection of tumors and improve survival.
In addition, patients with GIM have a significantly higher risk of developing cancer when accompanied by highly heterogeneous hyperplasia (HGD). A recent European study showed that if low-grade heterogeneous hyperplasia is found in patients with GIM, EGD should be repeated several times within 1 year with biopsy, and endoscopic surveillance can be suspended when two consecutive endoscopies and biopsies do not reveal heterogeneous hyperplasia.
HGD can be complicated by invasive adenocarcinoma and 25% of patients with HGD will progress to adenocarcinoma within one year, therefore patients diagnosed with HGD should undergo surgery or endoscopic resection. However, it remains controversial whether patients diagnosed with HGD must undergo empiric HP treatment.
Pernicious anemia
Patients with gastric adenocarcinoma presenting with pernicious anemia may be associated with type A atrophic gastritis, and studies have found that the risk of pernicious anemia is highest in the first year after diagnosis of gastric adenocarcinoma. However, the benefit of using endoscopic supervision for pernicious anemia remains unproven. Taking into account recent studies, ASGE recommends endoscopy after the diagnosis of pernicious anemia, with or without upper gastrointestinal symptoms.
Gastric carcinoid tumors
Gastric carcinoid tumors can be classified into 4 types: type 1 is characterized by multiple, highly differentiated and associated with type A chronic atrophic gastritis; type 2 is characterized by multiple, highly differentiated and associated with Zoe’s syndrome and multiple endocrine adenoma formation; type 3 is characterized by solitary, highly differentiated and disseminated; and type 4 is characterized by solitary and low differentiation.
The endoscopic evaluation of gastric carcinoid tumors should include the size, number, and distribution of the carcinoid tumors. Aspiration of gastric fluid for pH measurement and rapid serum gastrin level testing can be helpful in grading gastric carcinoid tumors when patients are not taking medications that affect gastrin levels. Regulatory strategies include endoscopic testing alone, endoscopic resection of small numbers of tumors, and surgical resection. Once gastric carcinoid tumors have been diagnosed endoscopically, EUS helps determine the depth of invasion and thus whether to consider EMR.
Gastric carcinoid tumors are more common clinically and often present with a benign course. 5 or 10 year survival rates for type 1 gastric carcinoid tumors are not different from the general population and clinical management includes endoscopic surveillance and endoscopic resection. 2 The incidence of type 2 gastric carcinoid tumors does not differ between men and women and lymph node metastases are present in 10-30% of patients by the time the disease is detected.
Type 2 gastric carcinoid tumors are often detected at an advanced stage, and the 5-year survival rate is often less than 50%. Due to the high incidence of lymph node infiltration, surgical resection should be considered for all type 3 gastric carcinoid tumors. Endoscopic resection should be considered only if the tumor is small (<1 cm) and highly differentiated.
After gastric surgery
Patients with benign gastric or duodenal ulcers are at elevated risk of developing gastric cancer after undergoing partial gastrectomy. Endoscopic follow-up studies have found that gastric cancer occurs in 4-6% of these surgical patients and that the process of heterogeneous hyperplasia to cancer occurs. In addition, studies have shown an increased risk of gastric cancer 15-20 years after the initial surgery.