Laparoscopic Resection of Gastric GIST Tumor

Abstract

This case illustrates a laparoscopic resection of a gastrointestinal stromal tumor (GIST): the most common mesenchymal tumor found in the gastrointestinal tract. GISTs can be found anywhere along the gastrointestinal tract; however, they are most commonly found in the stomach and small intestine. These tumors are often associated with mutations in the KIT (receptor tyrosine kinase) and PDGFRA (platelet-derived growth factor receptor alpha) genes. Because it is difficult to achieve a permanent cure using protein tyrosine kinase inhibitors, such as imatinib, surgical resection is the recommended therapy in most cases. While the surgical approach may vary on tumor characteristics, the laparoscopic approach is associated with low perioperative morbidity and mortality. 

Case Overview

Background

Gastrointestinal stromal tumors (GISTs), originating from the interstitial cells of Cajal, can be found anywhere along the gastrointestinal tract.^1, 2 These subepithelial tumors are most commonly found in the stomach and small intestine, and less commonly in the colon and rectum.¹ 

Focused History of the Patient

Here, we present the case of an 80-year-old woman who presented with gastrointestinal bleeding and was found to have a tumor located on the stomach. Its location on the anterior wall of the lesser curvature provides a suitable location for a wedge resection with a laparoscopic linear stapler. Despite this optimal position, care must be taken to avoid iatrogenic injury of the nerves of Latarjet. 

Physical Exam

Most GIST tumors are discovered incidentally on imaging studies or endoscopy. Patients can also present with abdominal pain and gastrointestinal bleeding.^{2, 3, 4, 5} These tumors can also present as part of familial syndromes, such as familial GIST syndrome, Neurofibromatosis type 1, and Carney-Stratakis syndrome.¹

Imaging

The majority of GISTs are discovered incidentally, often detected through endoscopic or radiographic studies, or surgery, performed for other reasons. CT with oral and intravenous contrast is the preferred imaging modality for a detailed evaluation of the tumor’s anatomic location as well as to look for metastatic disease. On CT, GISTs typically appear as hyperdense solid masses.⁵ Positron emission tomography (PET) scan can be used to gain information regarding the metabolic activity of a tumor, metastases, as well as response to chemotherapy, but is not recommended unless neoadjuvant chemotherapy is planned.⁵

Natural History

Most GIST tumors are asymptomatic and grow slowly. Although all GISTS have malignant potential, the risk of aggressive behavior is determined by size, location in the GI tract, and mitotic index. GISTs smaller than 2 cm are unlikely to pose much risk of either causing symptoms or metastasizing and therefore can be observed with serial imaging studies or endoscopy. GISTs larger than 2 cm should be removed.

Options for Treatment

Surgical excision is the standard therapy for a GIST.² Targeted therapy with Imatinib is used in the neoadjuvant setting when GIST tumors are locally advanced with the aim of converting the tumor to a status where an R0 resection would be possible. Resection of the tumor with a 1-cm margin is sufficient and more radical resections add morbidity without benefit. Since spread occurs hematogenously or via peritoneal seeding, there is no role for lymphadenectomy.

Discussion

The operative approach to GISTs is dependent on tumor size and location. Most can be removed with laparoscopic wedge resection. Very small tumors can be approached with endoscopic submucosal tunneling and resection, or endoscopic full-thickness resection, although one must question whether or not tumors of this size need to be resected at all. Intraoperative endoscopy is often performed to aid in localizing the lesion, determining the resection approach, and ensuring proper closure of the defect.⁵ Not all lesions can be excised using only a stapler so it is important that the surgeon have the facility to perform intracorporeal suture repair of the stomach, particularly for lesions close to the gastroesophageal junction or pylorus. Postoperatively most patients undergoing laparoscopic resection are discharged on post-op day 1 and do not require imaging studies.⁴ When tumors are close to the nerves of Latarjet, as in this case, patients should be monitored postoperatively for delayed gastric emptying, which can result when these nerves are injured.

The prognosis following resection of GISTs with clean margins depends on three factors: location in the GI tract (proximal is better than distal), tumor size, and mitotic index.⁶ Both the risk of recurrence and the intensity of follow up are determined using Fletcher’s risk classification.² This classification system risk-stratifies tumors by size, mitotic index, and the site of the primary tumor. A very low to intermediate risk is defined by a tumor size <5 cm and/or <5 mitoses per 50 HPF. High risk is defined by tumor rupture or tumor size >10 cm and/or >10 mitoses per 50 HPF. Using this classification system, those tumors ranging from very low to moderate risk are followed every six to twelve months by CT scan, while those in the high-risk group are reassessed every four to six months.² Adjuvant therapy with Imatinib is recommended for those patients with a >50% chance of recurrence as predicted by Fletcher’s risk index.⁷

Disclosures

Nothing to disclose.

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.