A component of preoperative planning involves a consideration of the accuracy of the preoperative diagnosis for GIST. The differential diagnosis includes other submucosal masses such as lipoma, carcinoids, and leiomyomas or sarcomas, and nongastric masses which originate from the liver, pancreas, or spleen, as well as lymphoma or germ cell tumors. The diagnostic yield of endoscopy with biopsy is 35%, endoscopic ultrasound with fine needle aspiration (FNA) 84%, abdominal computed tomography 74%, and magnetic resonance imaging 91%. Endoscopic ultrasound is valuable in assessing the gastric layer from which the lesion arises as well as providing access for biopsy if that is required.

Once an accurate diagnosis of GIST has been determined, preoperative planning will be guided by size, location, and relative intra/extra gastric configuration. The interplay of all of these factors will determine the ultimate operative approach. A large lesion that is very exophytic or pedunculated on the anterior wall of the gastric body
is a straight-forward laparoscopic resection and would be an entirely different operative approach from the same size lesion of the posterior antrum with an appreciable intragastric component which may require a standard distal gastrectomy. A posterior location may extend into the retroperitoneum requiring a pancreatic resection for complete removal. Transgastric or intragastric procedures should be considered for posterior wall or gastroesophageal junction tumors with an intragastric component. A wide variety of minimally invasive techniques are appropriate for GIST tumors which defies the concept of a single best approach for all patients. The integration and assessment of intraoperative endoscopy by the surgeon and diagnostic laparoscopy should guide operative decisions regardless of the preoperative plan.

Preoperative planning does require consideration of special equipment for many laparoscopic resections. A video endoscope, angled laparoscope, specimen retrieval bags, and endoscopic linear staplers are standard fare. Intragastric procedures where the operation occurs in an insufflated stomach with intragastric ports is a special operation which should be planned. It behooves the surgeon to be prepared with the following equipment if an intragastric approach is being contemplated.

Regardless of the specific operative approach, laparoscopic versus open, intragastric versus transgastric, formal resection versus wedge resection, the same surgical objective should be obtained: complete resection without tumor disruption. The principle goal of resection is obtaining macroscopically negative margins. The need to achieve microscopically negative margins is uncertain, since outcomes are likely determined by biologic tumor behavior and not the microscopic margin. The presence of a positive margin may be falsely interpreted based on specimen retraction, and re-excision is not advised for a microscopically positive only (R1) resection. Radical resection that would include lymphadenectomy is not required to ensure good outcomes, but a formal resection may be required based on size and location to achieve the best functional outcome. Extended resection should be done for contiguous organ involvement only to the degree that an RO or R1 resection is accomplished. A laparoscopic approach to resection is feasible, providing the same principles of traditional surgery are upheld: complete resection without tumor disruption. It was due to concern for tumor disruption by manipulation of the tumor that laparoscopy was initially discouraged, but its utility has been borne out in many series.