Efficacy analysis of adjuvant therapy with imatinib for gastric intermediate-risk gastrointestinal stromal tumor.

Abstract

e23510 Background: Accumulating evidence suggests that patients with high-risk gastrointestinal stromal tumor (GIST) can significantly benefit from adjuvant therapy with imatinib. However, the effect of this therapy in intermediate-risk GIST patients, particularly within gastric, has yet to be well demonstrated. Herein, we explored the efficacy of adjuvant imatinib in patients with gastric intermediate-risk GIST (GIGIST). Methods: The clinicopathologic and follow-up data on 93 GIGIST cases diagnosed from January 2005 to December 2016 at Union Hospital, Wuhan China were analyzed retrospectively. Univariate and multivariate analyses were performed to assess the prognostic factors for GIGIST. The patients were divided into three subgroups (Table) according to the multivariate analysis results to evaluate the efficacy of adjuvant imatinib. Results: We examined 43 male and 50 female patients with a median age of 60 years (range, 21-84 years). All patients underwent complete resection, and 42 (45%) patients were prescribed adjuvant imatinib 400 mg/day after surgery. The median adjuvant therapy period was 16 months (range, 12-72 months). The majority of the patients (86% [n = 80]) underwent followed-up for a median period of 46 months (range, 6-120 months). The 1-, 3-, and 5-year recurrence-free survival (RFS) rates in the whole group were 100.0%, 91.5% and 88.5%, respectively. Multivariate analysis revealed that the mitotic count (P = 0.040, relative risk (RR) = 6.078 [95% confidence interval (CI), 0.541-68.274]) and neutrophil-lymphocyte ratio (NLR; P = 0.036, RR = 6.102 [95% CI 0.782-47.632]) were prognostic risk factors for RFS. Adjuvant imatinib markedly increased the RFS rates in patients with a mitotic count greater than 2/50 high-power fields (HPF) and an NLR greater than 2.3 but not in the other two subgroups. Conclusions: GIGIST has a favorable overall prognosis. Patients with a mitotic count greater than 2/50 HPF and an NLR greater than 2.3 were identified as an advantageous group for adjuvant imatinib and targeted therapy longer than 1 year is strongly recommended to increase the RFS rate. Subgroup Mitotic count NLR Number of patients 1 ≤2 HPF Any value 28 2 > 2 to ≤10 HPF ≤2.3 28 3 > 2 to ≤10 HPF > 2.3 24