Laparoscopic Resection of Gastrointestinal Stromal Tumors of the Stomach

May 25, 2007
Surgical Rounds®, February 2006, Volume 0, Issue 0

Andrew J. Morse, Chief Surgery Resident; Christopher Evans, Associate Professor of Surgery, Department of Surgery, Memorial Hospital, York, PA

Gastrointestinal stromal tumors (GISTs) are uncommon and are preferentially treated by excision with good results. Morse and Evans report two cases of gastric GISTs that were successfully excised laparoscopically. Wide resections are not necessary because many GISTs are localized to areas of the stomach where a wedge resection can be performed. Suture closure of the area where the two staple lines meet is critical. Methylene blue is instilled into the distended stomach to check for leaks. If these tumors are in close proximity to the pyloric area, a distal resection may be required. The authors provide a good review of GISTs and thoroughly describe the laparoscopic technique.

Thomas Gadacz, MD, Series Guest Editor, Professor and Chairman, Department of Surgery, Medical College of Georgia, Augusta, GA

Andrew J. Morse, DO

Chief Surgery Resident

Christopher Evans, DO

Associate Professor of Surgery Department of Surgery Memorial Hospital York, PA

Gastrointestinal stromal tumors (GISTs) are relatively rare tumors of the gastrointestinal (GI) tract, usually occurring in the stomach (60% to 70%).1,2 They arise from mesenchymal cells of the GI tract. Although surgical resection offers the best chance for a cure, there is local and distant recurrence in 40% to 90% of cases.3,4

La?paro?scopic resection of benign gastric tumors has been deemed safe and effective,5,6 but there are few reports in the literature of laparoscopic resection of malignant gastric tumors.7,8 GISTs of the stomach are well suited for laparoscopic resection because the margin of resection allowable is relatively small and lymphadenectomy does not improve survival rates or affect recurrence.9 We report two cases of laparoscopic resection of gastric GISTs performed at a community-based teaching hospital. We also discuss the surgical management, follow-up protocols, and patterns of recurrence with these tumors, and review the variable success with che?motherapeutic agents such as imatinib.

Case reports

Case 1

?A 49-year-old man came to the hospital with acute GI bleeding. He was stabilized and received a transfusion of two units of packed red blood cells. Esophagogastroduodenoscopy was performed, which revealed a large 3.5 x 2.5-cm mass with ulcerations near the gastric antrum. The mass appeared to have a broad-based stalk. Biopsies revealed superficial fragments of normal gastric mucosa. Preoperative computed tomography (CT) studies did not show evidence of metastasis. Endoscopic resection of the mass was attempted with sclerotherapy of the base followed by wire loop electrocautery. The bulk of the tumor was removed, but the stalk had a large base and margins remained positive. The speci?men was determined to be a low-grade malignant epithelioid GIST. Im?muno?histochemical analysis showed the tumor cells were positive for vimentin, c-Kit tyrosine kinase (CD117), and CD34.

The patient returned to the operating room for laparoscopic resection of the GIST. A supraumbilical port was placed. Laparoscopic exploration did not reveal evidence of liver or peritoneal metastases. Additional ports were placed in the midepigastrium (5 mm), left upper quadrant (15 mm), and right upper quadrant (5 mm). Preoperative preparations were made for intraoperative esophagogastroduodenoscopy for tumor localization, but endoscopy was not needed because invagination of the serosa at the lesser curvature of the stomach made the tumor easily visible.

The tumor was determined to be amenable to a wedge resection without causing stenosis of the antrum. Portions of the lesser and greater omentum were taken down from the stomach using an ultrasonic dissector. The mass was grasped and gently elevated with an atraumatic bowel grasper, taking care not to disrupt the serosal surface and allow tumor spillage. A laparoscopic linear cutting stapler was used to take a wedge resection of the stomach encompassing the entire mass (Figure 1). Several applications of the stapler were required. The mass was placed in an endoscopic specimen retrieval bag and removed through the 15-mm port. A small rent created in the stomach by the stapler was closed with laparoscopically placed sutures. A mixture of water and methylene blue was instilled through a nasogastric tube to achieve gastric distention. No evidence of gastric leakage was observed and the solution was removed via the nasogastric tube. The specimen was opened on the back table and grossly tumor-free margins of resection were assured. The abdomen was thoroughly irrigated and suctioned. All instruments and ports were removed and the port sites were closed in the usual fashion.

The patient underwent an upper GI study on postoperative day 3, which showed no evidence of a gastric leak and revealed a widely patent gastric lumen. The patient was placed on a clear liquid diet and was discharged to home on postoperative day 4 with no evident complications. Follow-up CT and positron emis?sion tomography scans demonstrated no evidence of recurrence or metastasis.

Case 2

?A 65-year-old woman came to the hospital with anemia. As part of the workup, a CT scan was taken and revealed a gastric mass with no evidence of metastasis (Figure 2). Esophago?gas?tro?duodenoscopy was performed revealing a mass in the gastric antrum (Figure 3). Biopsies revealed normal gastric mucosa, consistent with a submucosal mass or external compression. Laparos?copic ex?ploration revealed the mass to be confined to the gastric wall. Wedge resection was performed, taking care to allow for adequate resection while preventing gastric outlet obstruction.

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The mass was found to be a low-grade epithelioid GIST, staining positive for CD117 and vimentin (Figure 4). The tu?mor came to within 1 mm of the serosal surface, consistent with a visible change in the serosa over a 4-mm area at mid- tumor. The patient later returned for an unrelated laparoscopic cholecystectomy, which allowed us to evaluate the area a second time. No evidence of local or met?astatic recurrence was visible. More than 212 years after their initial resections, both patients are recurrence free.

Discussion

GISTs are mesenchymal neoplasms of the GI tract, constituting 2% of all gastric malignancies.8,10 Although they are typically found in the stomach (60% to 70%),1,2 they can occur anywhere along the GI tract. The annual incidence of these tumors is 10 to 20 cases per million,11 with 5,000 to 10,000 new cases per year.3 GISTs usually occur in those older than 40 years (average age is 55 to 65 years).12 Previously diagnosed as leio?myo?sarcomas, GISTs are distinguished from other mesenchymal cell neoplasms by positive immunohistochemical staining for CD34 and c-Kit (CD117).1 These tumors are thought to originate from the interstitial cells of Cajal.13

Most GISTs are diagnosed inadvertently on CT scanning or during esophagogastroduodenoscopy, colonoscopy, lap?arotomy, or laparoscopy for unrelated reasons.13 The diagnosis is occasionally made when tumor necrosis leads to bleeding, prompting endoscopic evaluation.13 Preoperative staging is generally accomplished with an abdominal and pelvic CT scan and a chest radiograph.9

Surgical resection is indicated for patients with nonmetastatic GISTs. In some cases, minimally metastatic GISTs may also be resected along with the site of metastasis. Palliative surgery for symptomatic GISTs (such as those causing gastric outlet obstruction) should be undertaken regardless of metastatic status. Complete surgical resection improves the 5-year survival rate to 42% compared with 9% for incomplete resections.14

The standard approach in managing malignant gastric tumors has been subtotal or total gastrectomy via open laparotomy; however, these tumors present an important opportunity for surgeons to use advanced minimally invasive surgical techniques. The appropriate margin of resection for GISTs is minimal with reports indicating ranges from 1 cm to microscopically clear margins only.9 This makes laparoscopic stapled wedge resection a viable option for appropriately sized tumors. In our laparoscopic resections, clear margins were approximately 1.8 to 2 cm. GISTs rarely inv?ade ad?jacent organs, but tend to displace organs as the tumor enlarges.9 Lymph node me?t?astasis occurs in only 2% of patients, making lymphadenectomy unnecessary.9,14

Whether open or laparoscopic resection of GISTs is attempted, care must be taken to avoid tumor spillage intra-ab?dominally. Preoperative CT scans may detect tumors with unresectable metastasis. Visual or palpatory exploration of the abdomen should be performed intraoperatively to evaluate for gross evidence of metastasis. The most likely sites of me?tastasis are the liver and peritoneum.15 Gastric location, small tumor size, and low mitotic rate are good prognostic indicators; whereas esophageal and colonic location, large tumor size (>10 cm), and high mitotic rate are poor prognostic indicators.9

Sites of recurrence after resection in?clude local recurrence (25%), lymph node metastasis (2%), and distant metastasis (33%), of which 54% recurred in the liver and 20% recurred on the peritoneum.14 Postoperative follow-up regimens are not clearly reported in the literature. We opt for radiographic and endo?scopic surveillance every 6 months for the first 5 years. After 5 years, further surveillance is recommended only for those with unfavorable prognostic indicators.9

When limited recurrence or metastasis occurs, surgical resection remains a viable option. Although open surgery in such cases is likely advisable, we recommend laparoscopic exploration before a laparotomy. What appears to be minimal radiographic recurrence is often wide?spread peritoneal metastasis.16 In this situation, laparoscopic exploration may save a patient from the morbidity of an unsuccessful laparotomy.

Traditional chemotherapy has been unsuccessful in cases of GISTs. Imatinib has been the only known effective agent against these tumors. Imatinib works by blocking tyrosine kinase activity of c-Kit, activated in the case of GISTs by a "gain-of-function" mutation in the c-Kit protooncogene.16 Most research has been geared towards metastatic disease, but neoadjuvant and adjuvant therapy along with surgical resection to delay or prevent recurrence are currently being studied.16 External beam radiation therapy is rarely indicated and is generally of no proven benefit.9,14,16

Conclusion

Many nonmetastatic gastric GISTs are amenable to laparoscopic resection. Patient monitoring is essential in determining appropriate postoperative management so that recurrences can be discovered early and appropriate surgery or chemotherapy with imatinib can be in-itiated promptly. Due to the rarity of GISTs, data on these tumors are limited. Additional research with larger patient populations and longer follow-up periods is needed to confirm the success of the laparoscopic approach in managing gastric GISTs.

References

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