Analysis of clinicopathological features, gene mutation characteristics and prognosis of 228 cases of primary gastrointestinal stromal tumor of small intestine / 中华消化杂志

ABSTRACT

Objective:To analyze the clinicopathological features, gene mutation characteristics, and prognostic related factors of patients with primary gastrointestinal stromal tumor (GIST) of small intestine.Methods:From January 1, 2011 to December 30, 2019, surgical resected and pathological diagnosed small intestinal GIST without preoperative adjuvant therapy, at Tianjin Medical University Cancer Institute & Hospital were retrospectively collected. The mutational status of KIT exons 9, 11, 13, and 17 and platelet-derived growth factor receptor alpha ( PDGFRA) exons 12 and 18 were detected by polymerase chain reaction and Sanger direct sequencing. Clinicopathological features and gene mutation characteristics were analyzed. Pearson chi-square test and Bonferroni continuous correction test were used to compare the categorical variables among groups. Kaplan-Meier method and log-rank test were used for univariate survival analysis. The multivariate Cox proportional hazards regression model was used for multivariate survival analysis. Results:The proportions of patients with maximum tumor diameter> 10.0 cm and high-risk GIST located in the jejunum and ileum were higher than those of patients with primary GIST located in the duodenum (18.7%, 28/150 vs. 6.4%, 5/78; 56.7%, 85/150 vs. 43.6%, 34/78), and the differences were statistically significant ( χ2=14.67 and 12.46, P=0.002 and 0.006). The results of gene detection of 58 cases of small intestinal GIST indicated that the percentage of KIT gene mutant and wild type accounted for 84.5% (49/58) and 15.5% (9/58), among which 34 cases (69.4%), 12 cases (24.5%), 2 cases (4.1%) and 1 case (2.0%) were KIT gene exons 11, 9, 13 and 17 mutations, respectively, and none of the case with PDGFRA mutation. The 3-, 5-, and 10-year progression-free survival rates of the patients with small intestinal GIST were 88.1%, 85.0%, and 68.3%, respectively, and the 3-, 5-, and 10-year overall survival rates were 96.6%, 94.5%, and 86.1%, respectively. The results of univariate survival analysis showed that the progression-free survival rate and overall survival rate of patients with very low-risk and low-risk GIST were higher than those of patients with intermediate-risk and high-risk GIST (100.0%, 49/49 vs. 72.3%, 81/112; 100.0%, 49/49 vs. 89.3%, 100/112, respectively), and the differences were statistically significant ( χ2=14.07 and 4.92, P<0.001、=0.027). The results of univariate survival analysis of patients with intermediate-risk and high-risk GIST showed that the epithelioid cell type, mitotic index >5/5 mm 2, Ki-67 proliferation index >5%, and without postoperative adjuvant therapy were all related with progression-free survival time, and the differences were statistically significant ( χ2=8.39, 5.53, 13.73 and 15.44, P=0.004、0.019、<0.001、<0.001). Without postoperative adjuvant therapy was related with poor overall survival time ( χ2=7.06, P=0.008). The results of univariate analysis in patients with intermediate-risk and high-risk GIST and without postoperative adjuvant therapy showed that the epithelioid cell type, high-risk, mitotic index >5/5 mm 2 and Ki-67 proliferation index >10% were all related with progression-free survival time, and the differences were statistically significant ( χ2=10.08, 6.51, 10.37 and 15.72, P=0.001、0.011、0.001、<0.001). The results of multivariate analysis indicated that Ki-67 proliferation index >5% ( HR=5.018, 95% confidence interval(95% CI) 1.745 to 14.430, P=0.003) and without postoperative adjuvant treatment ( HR=0.145, 95% CI 0.051 to 0.414, P<0.001) were independent risk factors of postoperative tumor progression in patients with small intestinal intermediate-risk and high-risk GIST. Ki-67 proliferation index>10% ( HR=8.381, 95% CI 1.364 to 51.487, P=0.022) was an independent risk factor of postoperative tumor progression in patients with small intestinal intermediate-risk and high-risk GIST and without postoperative adjuvant treatment. Conclusions:The most common mutation in small intestinal primary GIST is KIT mutation, followed by wild type, no case of PDGFRA gene mutation has been found. High Ki-67 proliferation index can predict poor prognosis of patients with moderate-risk and high-risk small intestinal primary GIST. Postoperative adjuvant therapy can significantly improve the prognosis of patients with small intestinal intermediate-risk and high-risk primary GIST.