Results on prognostic value of mutations in localized gastrointestinal stromal tumors (GIST) in one single center

Introduction: to study the prognostic value of mutations in KIT or PDGFRA in gastrointestinal stromal tumors (GIST) managed in our department. Materials and methods: forty five patients with localized GIST underwent surgery between 1998 and 2010. Thirty six patients were enrolled in a retrospective study. DNA was isolated from 3 to 5 pm sections of fixed and paraffin-embedded tissue. Exon 9, 11, 13 and 17 of c-kit gene and exon 12 and 18 of PDGFRA were amplified by PCR and sequenced. Results: tumors with mutations were larger at the surgery and showed higher mitotic count (p < 0.05). The mutations were found in 22 patients (61.2%), 18 had mutations in exon 11 of c-kit gene. PDGFRA mutations were located in exon 12. The 5-years relapse-free survival rate for patients with tumors having mutations was 38% and 100% for patients without mutations (p < 0.01). The 5-year survival rate was significantly worse for patients with mutations (20 us. 97%, p < 0.01), with tumors larger than 5 cm (28 us. 97%, p < 0.01) and with > 50 mitosis/HPF (42 vs. 88%, p < 0.03). Multivariate analyses indicated that the mutations, mitotic counts, and tumor size were independent prognostic factors for survival in patients with localized GIST. Conclusions: in this series, having a detected mutation is a poor prognostic factor with significantly increased recurrence rate and shortens survival.