Adjuvant Imatinib Beyond 3 Years in High-Risk GIST: 5-Year Relapse-Free Survival Outcomes

BackgroundImatinib mesylate (IM) has changed the management of gastrointestinal stromal tumors (GISTs), especially for adjuvant therapy after radical resection. However, the optimal duration of the adjuvant therapy remains controversial. Therefore, this study evaluated the effect of adjuvant IM duration and plasma drug concentrations on survival outcomes of patients at high risk with GISTs.MethodsWe retrospectively analyzed patients diagnosed with high-risk GIST who underwent radical surgery at the First Affiliated Hospital of Chongqing Medical University between January 2008 and December 2021. Survival outcomes were compared according to adjuvant IM duration (≤3 years vs. >3 years). Plasma trough concentrations (Cmin) of IM were measured in a subset of patients and analyzed in relation to prognosis.ResultsThis study included 75 patients (42 males and 33 females), with a median age of 53 (24–79) years. Tumors were most commonly located in the small intestine (44 patients, 58.7%) and stomach (23 patients, 30.7%). Kaplan-Meier curve analysis showed that the 5-year relapse-free survival (RFS) rates were 84% and 74% in the groups with treatment duration >3 years and ≤3 years, respectively (P < 0.05), whereas no significant difference in 5-year overall survival (OS) was observed between the two groups (P > 0.05). In the multivariate analysis, treatment duration was not significantly associated with survival benefit (HR = 0.53, 95% CI 0.15–1.83, P = 0.313).ConclusionBased on this retrospective study, adjuvant IM for more than 3 years did not independently improve prognosis in patients with high-risk GIST following radical resection. Moreover, the clinical significance of IM Cmin remains unclear. Therefore, extending adjuvant therapy beyond 3 years is not routinely recommended at present. These findings require further validation through prospective studies.