Change in Size of Gastric Tumors Arising From the Muscularis Propria in Patients Undergoing EUS

Abstract

Purpose: To assess the change in size of gastric tumors arising from the muscularis propria, from initial to follow-up EUS. To determine appropriate time interval for follow-up EUS. Methods: A retrospective chart review of all upper EUS performed for suspected gastric subepithelial tumors during January 1, 2000 to November 1, 2007 was conducted using the EUS database of Duke University Medical Center and Wake Forest University Baptist Medical Center. Only patients who had at least one follow-up EUS were included. For each case, the following EUS findings were evaluated: length of follow-up period, interval size change, and number of EUS performed. The size of tumor was determined from the 2D EUS measurements of length and width of the tumor. Using the equation for the area of an oval (Area=π*a/2*b/2), the cross sectional area was calculated. Difference in the maximal cross sectional area from the initial to the follow-up exam was calculated. Frequency tables and scattered plots were used in the analysis. Results: Forty-nine patients were included. The average time interval between index EUS and 1st follow-up EUS was 17 months (+/− 13). The average size of the tumor on initial EUS was 107.79 mm2 (+/− 162). The average percent change in size from the initial to the follow-up was 3.67% (+/− 41%). Twenty-four patients (49%) showed decrease in size with an average decrease by 25% (+/− 21%). Twenty-three patients (47%) showed increase in size with an average increase by 34% (+/− 37). If the average decrease in size is the endosonographer's margin of error in determining the length and width of the tumor, then the average increase in size of tumors is 9% (not statistically significant). Assuming 50% change in size as a clinically significant change, only 4 patients (8.2%) demonstrated this. Of the four, two had follow-up at 12 months and other two had repeat EUS in their third year. Only one of the two who had follow-up at one year showed a dramatic increase in size of the tumor indicating potential for malignancy. Conclusion: In this retrospective two center study, EUS was frequently utilized in the surveillance of gastric tumors arising from the muscularis propria. This study showed no statistically significant increase in the size of the tumors. A longer time interval (>17 months) for subsequent EUS should be entertained during the surveillance of these lesions.