Gastrointestinal Stromal Tumors Risk of Recurrence Stratification by Tumor Volume is a Best Predictor Compared with Risk Based on Mitosis and Tumor Size

Abstract

Purpose: Gastrointestinal stromal tumors (GIST) have the potential to recur and metastasize. Several prognostic schemes have been developed, mostly based on the mitotic count, diameter, and tumor site. However, these systems are not precise enough. The research question was whether the tumor size determined by volumetry allows a better risk stratification than the traditional system, and our aim was to determine the value of tumor volumetry, a feasible and simple parameter, in the recurrence of GIST. Methods: Seventy-four cases of GIST were studied. The cases presented with non-metastatic disease, which were resected and did not receive imatinib. We compared the clinico-pathologic features of the cases with recurrence against those with non-recurrence and compared the tumor volumetry against the classification system based on tumor size and mitosis. Results: The median age was 58 years (range: 25 to 91 years). Half of the cases were presented in the stomach. The tumor size had a median of 8 cm (range of 1–30 cm). The median mitosis count for 50 HPF was 4 (range 0–92). During the period of study, 16 (21.6%) patients suffered recurrence. The significant differences were that patients with recurrence accounted for more deaths and the follow-up period was larger. The area under the curve (AUC) of the volumetry classification was superior to the AUC of the classification system based on tumor size and mitosis (NIH-criteria) (p =.05). Conclusion: Tumor volumetry calculated in the surgical specimen and/or pre-operative tomography was superior to the NIH consensus in stratifying the risk of recurrence in GIST.