Ki67 and Tumor Size as Prognostic Factors of Gastrointestinal Stromal Tumors

摘要

Background The aim of the study is to determine useful prognostic factors of gastrointestinal stromal tumors (GIST). Methods 135 patients with GIST in the stomach resected at the Cancer Institution Hospital were retrospectively reviewed. Results 84% were positive for KIT and/or CD34. All events of death due to GIST, metastasis to lymph nodes, liver and other sites occurred in patients with KIT and CD34 positive GIST. Univariate Cox regression analyses revealed that ulceration, tumor size and Ki67 index were significant predictors of death due to GIST with KIT and/or CD34 positive stain. On the other hand, multivariate Cox regression analysis showed tumor size >50mm [hazard ratio: 6.9 (95% confidence interval: 1.6-30.1)] and Ki67 index>=40/mm~2 [hazard ratio: 8.0 (95% confidence interval: 2.6-25.1)] were the only significant poor prognostic factors. Prognosis of patients with KIT and/or CD34 positive GIST satisfying both conditions of larger than 50mm in tumor size and Ki67 index >=40/mm~2 was significantly poorer than in others (log-rank test: P<0.0001): 5 year-survival rate: 36% vs. 95%. Conclusion These results suggest that patients with KIT and CD34 positive GIST larger than 50mm in tumor size and greater than 40 in Ki67 index may have poor prognosis.