Benign Gastric Tumors Treatment & Management

Of the large variety of gastric tumors, the gastrointestinal (GI) stromal tumor (GIST) is the only type that has a real systemic medical therapy because of the expression of Kit (tyrosine kinase receptor). ^[13]

Imatinib mesylate is a small-molecule receptor inhibitor that targets Kit. Clinical trials have shown partial response rates of 40-69% progression-free survival in patients treated with imatinib for advanced, recurrent, or metastatic GISTs. It has been used in the preoperative treatment of patients with GISTs that are imatinib-responsive to decrease tumor size before surgical resection. ^[14]  Imatinib resistance is common, however; thus, therapy generally is not curative. ^[15]

A clinical practice guideline for gastrointestinal stromal tumors (GISTs) was published by the European Society for Medical Oncology (ESMO), the European Reference Network for Rare Adult Solid Cancers (EURACAN), and the European Reference Network for Genetic Tumour Risk Syndromes (GENTURIS) in September 2021. ^[16] (See Guidelines.) This guideline also cites alternatives for patients with advanced or metastatic disease whose tumors have specific mutations or who are unresponsive to or intolerant of imatinib.

Gastric polyps

Gastric polyps include the following types:

• Hyperplastic polyps
• Adenomatous polyps
• Fundic gland polyps
• Inflammatory fibroid polyps

Endoscopic excision of gastric polyps provides a minimally invasive approach to diagnosis and treatment. ^[17] Polyps smaller than 2 cm are easily snared. Larger polyps or sessile polyps are best removed operatively to obtain a clear margin and complete removal. Occasionally, staged piecemeal endoscopic removal can be performed in patients with severe comorbidities.

Wide, local, or segmental resection of the stomach may be performed for multiple polyps, depending on their histology and location. Gastrectomy is justified in patients with diffuse involvement of the stomach by polyps, which can make detection of a synchronous focus of cancer difficult.

Hyperplastic polyps are by far the most common histologic type, and they can vary in location, number, and size. Most are smaller than 2 cm. Although these polyps typically harbor no malignancy, they may be accompanied by atrophic gastritis, which predisposes the nonpolypoid mucosa to malignant transformation. A Portuguese study reported a 5.1% rate of neoplastic transformation for gastric hyperplastic polyps. ^[18] Multiple hyperplastic polyps are found in Ménétrier disease. The histology of these polyps is different from that of colorectal polyps in that it shows submucosal edema and faveolar hyperplasia.

Most gastric hyperplastic polyps can be detected and treated with endoscopy alone. The current view is that gastric hyperlpastic polyps larger than 5 mm should be removed whole, especially if they are pedunculated. ^[11]

Adenomatous polyps (tubular and villous) are usually solitary lesions in the antrum. They have atypical cells and are associated with adenocarcinoma of the stomach. This association is strongest in polyps greater than 2 cm in diameter. The overall incidence of complete malignant transformation in adenomatous polyps is about 3.4%.

Fundic gland polyps contain microcysts that are lined by fundic-type parietal and chief cells, and they are located in the fundus and body of the stomach. They are common in familial polyposis syndromes and have no malignant potential.

Inflammatory fibroid polyps ^[19] are benign spindle cell tumors that are infiltrated by eosinophils, but they are not associated with a systemic allergic reaction or eosinophilia. Excision of inflammatory fibroid polyps is indicated because of their propensity to enlarge and cause obstruction.

Polyposis syndromes

Sometimes polyps in the stomach are associated with polyposis syndromes. These syndromes include juvenile polyposis, Gardner syndrome, Peutz-Jeghers syndrome, and Cronkhite-Canada syndrome.

Juvenile polyposis and Cronkhite-Canada syndrome rarely result in gastric cancer.

Peutz-Jeghers syndrome involves gastric hamartomatous polyps. The gastric involvement is generally less than that observed in the small intestine. These polyps can bleed or obstruct the antrum and should be treated accordingly. Although patients with Peutz-Jeghers syndrome may occasionally develop gastric cancer, other non-GI cancers are more common.

Adenomatous polyps of the stomach and duodenum develop in 50% of cases of familial polyposis and Gardner syndrome. Polyps are usually multiple, and they are best treated endoscopically. Multiple treatments every 3-4 months may be necessary for complete eradication. Routine surveillance endoscopy should be instituted as a life-long program. Patients with Gardner syndrome develop adenomatous polyps in the duodenum as well as in the stomach and should undergo routine esophagogastroduodenoscopy (EGD).

Nonmucosal intramural tumors

Leiomyomas formerly comprised the most common submucosal tumors of the stomach. Many tumors formally designated as leiomyomas (and leiomyosarcomas) are now classified as GISTs and are believed to arise from interstitial cells of Cajal rather than from smooth muscle per se. The overall incidence of GISTs is approximately 4 per 1 million in the general population. These lesions can be found throughout the GI tract from the esophagus to the rectum; however, the stomach is the most common site.

Most patients with GISTs are asymptomatic, but anemia and acute GI bleeding from tumor ulceration can occur.

There is a spectrum from benign to malignant. Histologic characteristics, such as the number of mitotic figures, tumor necrosis, and cellularity, are indicators of malignancy. The only reliable indicator of malignancy in these and other GISTs is evidence of extragastric spread. Lymphatic spread is rare, but hematogenous spread to the liver and the lungs is more common.

These tumors can cause symptoms by obstruction, ulceration, and blood loss or by compressing adjacent organs. They appear as large submucosal lesions on endoscopy, and endoscopic biopsies are invariably not deep enough to be of any diagnostic value; meticulous endoscopic examination is essential. ^[20]

As defined by the GIST Consensus Conference, the goal of treatment should be complete resection of visible as well as microscopic disease, while avoiding tumor rupture and obtaining negative margins. Because of the adequacy of a narrow margin of resection, there has been significant interest in developing operative techniques that accomplish effective tumor resection but minimize morbidity, preserving stomach parenchyma, and reduce medical costs.

Minimally invasive surgery has proved effective for GIST resection, with shorter hospital stays and comparable operating room time and blood loss in comparison with open techniques. ^{[21, 22, 23, 24, 25, 26]}  The GIST Consensus Conference recommended laparoscopic resection for tumors less than 2 cm, and several studies found laparoscopic treatment to be safe and effective in tumors averaging 4.4 cm. ^{[27, 28, 26]} The pathologic phenotype and especially the tumor mitosis correlate significantly with patient survival, even if the resected tumor size was relatively small. ^[29]

For GISTs located in the fundus, along the greater curvature, a laparoscopic gastric wedge resection may be beneficial. Tumors in the lesser curvature are less likely to be effectively resected via laparoscopy because of the limited mobility of the stomach in this area. For esophagogastric junction (EGJ) tumors, the laparoscopic transgastric procedure can be used successfully. ^[27]

Endoscopic resection seems to be an effective and safe method for smaller (≤ 4.0 cm) GISTs originating from the muscularis propria; for some intermediate- or high-risk GISTs, adjuvant therapy or additional surgical procedures might be required to reduce the risk of recurrence or metastasis. ^[30]

Endoscopic mucosal resection (EMR)—including variants such as EMR with ligation (EMR-L), EMR with double ligation (EMR-DL), and EMR after circumferential precutting (EMR-P)—has been advocated for use in surgical management of subepithelial gastric tumors. ^[31]

Patrzyk et al reported increased patient satisfaction with the final cosmetic appearance after single-port resection using a laser-supported diaphanoscopy. ^[32]

Lipomas are rare submucosal tumors that are sometimes indistinguishable from GISTs. They represent deposits of adipose tissue in the wall of the stomach, usually in the submucosa. They may cause symptoms when exceeding 2 cm in size. The standard treatment is surgical resection, but endoscopic treatment has been proposed for lesions smaller than 2 cm. ^{[33, 34]}

Fibroma and fibromyoma are most commonly observed as small intramural or subserosal lesions during the course of an unrelated surgery. Removal is warranted to confirm their benign nature.

Ectopic pancreas can occasionally cause symptoms by obstructing the pylorus or bleeding. Characteristic findings on endoscopy include a nipplelike appearance and a central ductal orifice. Histologic evaluation can reveal acute and chronic pancreatitis and cystic dilatation of the duct. Asymptomatic lesions require no further treatment. Local full-thickness excision of the gastric wall is adequate for complete removal.

Cystic tumors can be mucocele or intramucosal, and they are the most common benign cystic lesion of the stomach. They develop as a result of obstruction of mucus-secreting glands. Duplication cysts are congenital lesions that share a common wall with the stomach but do not communicate with the lumen. They enlarge because of trapped secretions, resulting in symptoms of obstruction. Treatment of duplication cysts is operative excision.