Diagnostic and treatment strategy for small gastrointestinal stromal tumors

Abstract

Gastrointestinal stromal tumors (GISTs) are considered to be potentially malignant mesenchymal tumors of the gastrointestinal tract. Clinically relevant GISTs are rare; however, subclinical GISTs (mini-GISTs) (1-2 cm) and pathologic GISTs (micro-GISTs) (<1 cm) are frequently reported. Most mini-GISTs and almost all micro-GISTs of the stomach may exhibit benign clinical behavior, and only mini-GISTs with high-risk features may progress. For this review, a provisional algorithm was used to propose diagnostic and treatment strategies for patients with small GISTs. Because surgery is the only potentially curative treatment, in its application for small GISTs, the principles of sarcoma surgery should be maintained, and cost effectiveness should be considered. Indications for surgery include GISTs measuring ≥2 cm, symptomatic GISTs, and mini-GISTs with high-risk features (irregular borders, cystic spaces, ulceration, echogenic foci, internal heterogeneity, and tumor progression during follow-up); however, a preoperative pathologic diagnosis is infrequently obtained. For small intestinal and colorectal GISTs, surgery is indicated irrespective of size because of their greater malignant potential. Otherwise, mini-GISTs without high-risk features, micro-GISTs, and small submucosal tumors measuring <5 cm without high-risk features may be followed by periodical endoscopic ultrasonography. Although surgical approaches and operative methods are selected according to tumor size, location, growth pattern, and surgical teams, laparoscopic surgery has produced similar oncologic outcomes and is less invasiveness compared with open surgery. After resection, pathologic examination for diagnosis and risk assessment is mandatory, and genotyping is also recommended for high-risk GISTs. Endoscopic resection techniques, although feasible, are not routinely indicated for most mini-GISTs or micro-GISTs. Cancer 2016;122:3110-8. © 2016 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Keywords: endoscopic ultrasonography (EUS); gastrointestinal stromal tumor (GIST); high-risk features; laparoscopic surgery; submucosal tumor (SMT).

Figure 1

Approaches to pathologically undiagnosed submucosal tumors (SMTs) and pathologically confirmed gastrointestinal stromal tumors (GISTs) are illustrated. Therapeutic approaches for pathologic GISTs are divided by size (ie, ≥ 2 cm, 1‐2 cm, and <1 cm). High‐risk features include irregular border, cystic spaces, ulceration, echogenic foci, heterogeneity, and progression during follow‐up. CT indicates computed tomography; EUS, endoscopic ultrasonography; EUS‐FNA: endoscopic ultrasonography‐guided fine‐needle aspiration biopsy.

Figure 2

Representative high‐risk endoscopic and endoscopic ultrasound (EUS) features of gastrointestinal stromal tumors are shown, including (A1,A2) irregular borders and echogenic foci, (B1,B2) heterogeneity, (C1,C2) cystic spaces, and (D1,D2) ulceration.

Figure 3

Several laparoscopic approaches to small gastric gastrointestinal stromal tumors that exhibit intraluminal or extrinsic growth are illustrated. Resection of a tumor on the lesser curvature appears to be challenging with a laparoscopic approach in terms of postoperative deformity and stasis. A sophisticated surgical technique is required to minimize deformity of the remnant stomach and to preserve branches of the vagal nerve.

Figure 4

The laparoscopic and endoscopic combined approach is illustrated. (A) In the classical style of “laparoscopic and endoscopic cooperative surgery” (LECS), after submucosal injection, a mucosal incision and a subsequent seromuscular incision are performed endoscopically, followed by an intentional perforation of the gastric wall. The full‐thickness defect is sutured laparoscopically using a linear stapler or a hand‐suturing technique, and the resected tumor is laparoscopically retrieved. (B) With the “combination of laparoscopic and endoscopic approaches to neoplasia with nonexposure technique” (CLEAN‐NET), after laparoscopic seromuscular incision, the full layer, including the tumor, is pulled out by dragging several suture threads. The tumor is resected with linear staplers and is laparoscopically retrieved. (C) With “nonexposed endoscopic wall‐inversion surgery” (NEWS), after laparoscopic seromuscular incision, seromuscular layers are linearly sutured with a surgical sponge as a spacer, which may push the tumor into the gastrointestinal lumen. The protruded lesion is endoscopically resected using the endoscopic submucosal dissection (ESD) technique and is transorally retrieved.