Introduction

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor originating in the gastrointestinal tract, originating from the interstitial cells of Cajal. GISTs occur most commonly in the stomach (60%), followed by the small intestine (30%) [1].

The standard of care for localized GISTs is complete surgical resection without dissection of clinically negative lymph nodes [2]. Any GIST is considered potentially malignant, indications for surgery for gastric GISTs are as listed below. For non-gastric GISTs, surgical resection is recommended regardless of tumor size or morphology [3].

Indications for Surgery for Gastric GISTs

  1. 1.

    Tumor >2 cm.

  2. 2.

    Increase in size on follow-up.

  3. 3.

    Signs of malignancy; irregular margins, cystic changes, necrosis, and heterogenous echogenicity.

  4. 4.

    Symptomatic; ulceration and bleeding, gastric outlet obstruction (large antral GISTs).

The goal of surgery is R0 surgery (i.e., excision margins are clear of tumor cells). While laparoscopic surgery for gastric GISTs resection is associated with superior postoperative outcomes, the decision to undertake laparoscopic versus open surgery should be made at the discretion of the surgeon. The European Society for Medical Oncology (ESMO) guidelines discourage laparoscopy for patients with large tumors due to the risk of tumor rupture [2], while Otani et al. [4] suggest 5 cm as the limit for laparoscopic wedge resection. Intraoperative tumor rupture is associated with a very high risk of peritoneal relapse [5].

The initial diagnosis of a GIST is usually suggested by endoscopy, endoscopic ultrasound (EUS), or computed tomography (CT) of the abdomen. Preoperative histological diagnosis is not necessary unless considering neoadjuvant imatinib therapy [3]. Neoadjuvant imatinib therapy should be considered for localized GISTs when R0 resection is not feasible or for organ preservation [3]. En bloc resection of a GIST that has invaded surrounding organs may be necessary to achieve negative margins and to avoid tumor rupture [6]. The principles of surgery for GIST are negative margins, and resection without rupture of the tumor.

Surgical Technique

Instruments

  • 12 mm ports, 5 mm ports

  • Nathanson retractor (for proximal gastric GISTs if liver retraction is required. Alternative methods of liver retraction may be used).

  • 10 mm 30° laparoscope

  • Advanced energy device—author preference is the Harmonic 1000I.

  • Atraumatic graspers.

  • Clip applicator.

  • Suction/irrigation device.

  • Laparoscopic stapler.

Operating Room Setup and Patient Position

The patient is placed in the supine position with both arms out and a footboard. The laparoscopic stack is placed on the patient’s left, the machines for the energy devices are placed at the patient’s feet, and the suction machines are placed on the patient’s right.

The main surgeon stands on the patient’s right along with the camera assistant, while the first assistant stands on the patient’s left.

After the subumbilical port is placed, the abdominal cavity is inspected for evidence of peritoneal metastasis. Pneumoperitoneum is maintained at 12 mmHg. Location of the ports depends on the location of the tumor, but is generally similar to that used in laparoscopic gastrectomy.

Operative Steps

Stapled wedge resection can be easily performed for most anterior wall gastric GISTs. Tumor rupture must be avoided at all cost. The tumor should be handled gently if at all, while and the surrounding tissues can be sutured or handled for traction. To avoid stenosis, the tumor should be elevated and the stapler fired perpendicular to the long axis of the stomach. An extraction bag is recommended for retrieval of the specimen.

For tumors in the posterior gastric wall, the greater omentum may need to be incised in the avascular portion away from the gastroepiploic arcade in order to enter the lesser sac to reach the tumor.

For tumors near the greater or lesser curve, the omentum and feeding vessels will need to be ligated and dissected free in order to perform a wedge resection. This is best done with an energy device.

The most challenging gastric GIST surgeries are for endophytic tumors, or tumors located in the fundus, lesser curve, and the antrum.

Endophytic Gastric GIST on the Anterior Gastric Wall

Endophytic Tumors Located on the Anterior Gastric Wall (Fig. 1)

Fig. 1
A surgical photograph of endophytic GIST on the anterior gastric wall.

Endophytic GIST on the anterior gastric wall

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  • An incision is made on the anterior gastric wall adjacent to the tumor.

  • The tumor is then everted through the gastrostomy and lifted anteriorly (Fig. 2).

  • Lift both edges of the gastrostomy and staple across, resecting the tumor and stapling close the gastrostomy at the same time. Alternatively, the tumor can be excised with a stapler and the gastrostomy subsequently closed with sutures.

Fig. 2
A photograph of a surgical procedure in a tumor.

Eversion of tumor through an adjacent gastrostomy

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Endophytic Gastric GIST on the Posterior Gastric Wall

  • An incision is made on the anterior gastric wall overlying the tumor (Fig. 3).

  • The posterior wall tumor is lifted up through the gastrostomy and resected with a stapler (Fig. 4).

Fig. 3
A surgical image of anterior gastrostomy overlying the tumor.

Anterior gastrostomy overlying the tumor

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  • The anterior wall gastrostomy is closed with a stapler or with sutures.

Fig. 4
A photograph of a tumor in a round form.

Posterior wall tumor lifted through a gastrostomy on the anterior wall

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Antral GISTs

  • Stapled wedge resection of broad antral tumors may be difficult to perform due to the thickened musculature of the antrum, making it less mobile.

  • Anterior wall tumors may be excised with an energy source, such as harmonic, and the gastrostomy closed transversely to prevent strictures. A gastrojejunostomy can be performed if there is concern of stenosis of the antrum/pylorus after excision.

  • In cases of large antral GISTs, it may not be possible to perform a wedge resection. A distal gastrectomy may be required to achieve negative resection margins.

Fundal/Lesser Curve/Cardioesophageal Junction (CEJ) GISTs

  • Resection of a fundal or lesser curve tumor should be performed over a bougie or gastroscope to ensure that the CEJ is not narrowed.

  • Intragastric resection may be performed for tumors located in the posterior wall near the CEJ, whereby laparoscopic ports are placed through the anterior gastric wall into the gastric lumen, and stapler resection is performed.

Other methods such as endoscopic submucosal dissection have been described. However, enucleation of GISTs is not considered standard treatment as GISTs do not form a true capsule, originates from the muscle layer (unlike early gastric cancer), and disruption of the pseudocapsule and perforation of the gastric wall may happen simultaneously resulting in peritoneal dissemination [7].

Postoperative Management

Margin status may not be a significant prognostic factor for GIST recurrence [8]. In cases where the resection margin has microscopic tumor cells (R1), postoperative imatinib therapy is recommended when the malignant potential is high (based on size and mitotic index). Routine surveillance can be performed for low-risk GISTs [3].