Impact of KIT and PDGFRA gene mutations on prognosis of patients with gastrointestinal stromal tumors after complete primary tumor resection.

INTRODUCTION: To investigate the impact of KIT and PDGFRA gene mutations on the prognosis of gastrointestinal stromal tumors (GIST).
MATERIAL AND METHODS: Tumor tissue from 184 patients with primary GIST was submitted to mutational analysis of exons 9, 11, 13, and 17 of the KIT gene and exons 12 and 18 of the PDGFRA gene. Clinical and pathological parameters were analyzed and correlated to the risk of recurrence and disease-free survival (DFS). RESULTS AND DISCUSSION: The authors found that somatic mutations were detected in 162 tumors (88.0%). Age, clinical stage, mitotic count, and tumor size were of prognostic relevance on both univariate and multivariate analysis. Five-year DFS was 41.9%. While the presence of a KIT or PDGFRA mutation per se was not associated with tumor recurrence and/or disease-free survival, exon 11 deletion and hemizygous mutation status were both independent factors highly predictive for poor survival.
CONCLUSION: The authors conclude that KIT exon 11 deletions and somatic loss of the wild-type KIT identified patients with poor prognosis. Age, clinical stage, tumor size, and mitotic count were standard clinicopathologic features that significantly influenced the prognosis. Mutation type of the mitogen receptor c-kit has a potential for predicting the course of the disease and might contribute to management individualization of GIST patients.