Association of endoscopic ultrasonographic parameters and gastrointestinal stromal tumors (GISTs): can endoscopic ultrasonography be used to screen gastric GISTs for potential malignancy?

BACKGROUND: Previous research shows that only 10-30% of gastrointestinal stromal tumors (GISTs) are malignant. Nonetheless, some reports suggest that all of them have some degree of potential for malignancy. Endoscopic ultrasonography (EUS) is a useful technique for differentiation of subepithelial lesions in the gastrointestinal tract. We explored EUS characteristics that might predict the malignancy potential of GISTs. METHODS: In this retrospective review of the medical records from 1999 through 2007, patients who had gastric stromal tumors diagnosed prior to surgery using EUS were enrolled. The EUS images, procedure records and tissue histopathology were reviewed. All patients were positive for C-kit. RESULTS: Of the 110 patients enrolled, 57 were males, and 53 were females. Most (67%) of the GISTs were located in the gastric body. The lesion size ranged from 6.3 to 150 mm (mean ± SD: 39.73 ± 22.49 mm). The high-risk GIST group had 19 (17.3%) patients, the intermediate-risk group had 12 (10.9%) patients and the low/very low-risk group had 79 (71.8%) patients. Thirty patients had cystic lesions (27.3%), while six patients had calcification in the lesion (5.5%). Additionally, 27 patients (24.5%) had surface ulceration visible on endoscopy. GISTs at high risk for malignancy were highly associated with lesion size (p < 0.0001), cystic change (p = 0.015) and surface ulceration (p = 0.036) but not with calcification (p = 0.667). We also found that mitosis was associated with lesion size (p < 0.0001) rather than other parameters. Age was not predictive of malignancy potential (p = 0.316). However, tumor size is the only one independent risk factor for malignancy (p ≤ 0.0001). CONCLUSIONS: The preliminary results show that large gastric GISTs with cystic change and surface ulceration may associate with a risk of malignancy, warranting more aggressive management. Nevertheless, the tumor size is more important than other factors.