Chapter 25

In the accompanying chapter, Dr Raut provides an overview of gastrointestinal stromal tumor (GIST). Clearly, the development of tyrosine kinase inhibitors for GIST is one of the most remarkable achievements to date for any solid tumor. Patients with metastatic GIST historically had a median survival of 12 months, but it is now 5 years.1,2 The paradigm of targeted molecular therapy has been subsequently expanded to lung adenocarcinoma with epidermal growth factor receptor (EGFR) inhibitors, renal carcinoma with vascular endothelial growth factor receptor (VEGFR) inhibitors, and most recently melanoma with B-Raf inhibitors. Although GIST is an uncommon tumor, lessons from “the GIST story” will have relevance to the multimodality therapy of these more common tumors and other cancers for which targeted therapy is developed.

Despite the advances in molecular therapy, it is critical to realize that surgery remains the only potentially curative treatment for GISTs. There are no data to support chronic therapy with molecular agents instead of surgical removal in patients who are otherwise healthy and expected otherwise to have prolonged survival. Thus, a thorough understanding of the surgical principles for GIST is essential.

There are a variety of surgical issues in GIST that deserve emphasis. First, it is important to handle GISTs gently, as they are often soft and prone to tumor rupture. They may become even more friable after response to neoadjuvant therapy. During laparoscopic resections, specimens should be placed into a plastic bag prior to removal from the abdominal cavity. Large GISTs tend to have extensive arterial and venous collaterals. Thus, careful dissection is necessary to minimize the chance of significant blood loss. While GISTs tend to push surrounding structures as opposed to invading them, if a GIST is adherent to a contiguous organ, it is necessary to remove the tumor en bloc with a portion of that organ.

The site and size of a primary GIST influence the surgical approach. For small- to medium-sized tumors, laparoscopic resection can be used. Some of these tumors will be cured by surgery alone as they generally tend to have low mitotic rates. Gastric GISTs are often easily identified at surgery because they tend to be exophytic. Tumors that grow more inward toward the gastric lumen may require intraoperative endoscopy to localize the exact site for partial gastrectomy. Intraoperative ultrasound may also be useful and is facilitated by instilling water into the stomach. Tumors arising from the posterior wall of the stomach are slightly more challenging to remove but still often can be removed laparoscopically after adequate stomach mobilization. It is often helpful during laparoscopy to retract the left lateral segment of the liver to the right to fully expose the stomach. Most gastric tumors can be removed using surgical staplers. Generally, a 1-cm margin of normal tissue is adequate. As Dr Raut mentions, it may not be possible or necessary to have a preoperative tissue diagnosis. Therefore, patients should be informed that their tumor may ...

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