An Evaluation of 2537 Gastrointestinal Stromal Tumors for a Proposed Clinical Staging System

Hypothesis: A gastrointestinal stromal tumor (GIST) staging system can be created with the Surveillance, Epidemiology and End Results (SEER) database. Design: A review of records in the SEER database from 2537 patients with GISTs from June 1, 1977, through August 1, 2004. Patients and Methods: Patients were compared using all available clinicopathologic factors, and a TGM (tumor, grade, metastasis) staging system was created according to these parameters. Survival data were analyzed using Kaplan-Meier methods, log-rank analyses, and Cox regression models. Results: Median follow-up time was 21 months, 47.6% of patients were men, and the median age was 64 years; 5.0% had lymph node involvement, and 22.6% had distant metastasis. Tumor size (T1, <= 70 mm; T2, >70 mm; P <.001), grade (G1, grades I and II; G2, grades III and IV; P <.001), and the presence of metastases (M0, no; M1, yes; P <.001) did affect overall survival. When combined in a TGM staging system, grade and metastasis were the factors most predictive of survival. Conclusions: A staging system for GISTs that provides valuable prognostic information was developed. Further work to refine this system and validate it with other data sets should be undertaken. Mitotic index and standardized reporting may provide additional prognostic information and should be recorded for all tumors so that the most accurate staging system can be created.