[Optimal duration of preoperative imatinib therapy in locally advanced gastrointestinal stromal tumors]

Objective: To explore the optimal duration of preoperative imatinib therapy in patients with locally advanced gastrointestinal stromal tumors (GIST) in order to optimize surgical timing and long-term survival benefits. Methods: A total of 171 patients with locally advanced GIST who received preoperative imatinib therapy and subsequent surgical resection between November 2012 and October 2024 at Fujian Cancer Hospital and Union Hospital of Fujian Medical University were retrospectively analyzed. Patients were divided into three groups according to the duration of preoperative imatinib treatment: short-term (≤6 months, n=50), intermediate-term (7-12 months, n=87), and long-term (>12 months, n=34). Imaging response, pathological efficacy, recurrence-free survival (RFS), and overall survival (OS) were compared among the groups. Univariate and multivariate Cox regression analyses were used to identify the optimal treatment duration. Results: The median duration of preoperative imatinib therapy was 9 (6, 12) months. After treatment, the average maximum tumor diameter decreased from (10.37±5.74) cm to (6.99±4.34) cm, with an average shrinkage of 31.5%. The objective response rates in the short-, intermediate-, and long-term groups were 50.0% (25/50), 58.6% (51/87), and 52.9% (18/34), respectively; high-grade pathological response rates were 28.0% (14/50), 37.9% (33/87), and 29.4% (10/34), with no statistically significant differences among groups (all P>0.05). With a median follow-up of 46 months, 39 patients experienced recurrence and 20 died. The intermediate-term group had 3- and 5-year RFS rates of 87.1% and 79.6%, respectively, significantly better than those of the short-term group (75.5% and 55.5%, P=0.004). The long-term group had 3- and 5-year RFS rates of 85.3% and 75.5%, which were between the other two groups, but not significantly different (all P>0.05). For OS, the intermediate-term group had 3- and 5-year rates of 97.3% and 92.7%, superior to the short-term group (84.4% and 72.4%, P=0.007), while the long-term group (88.2% and 79.4%) showed no significant advantage (all P>0.05). Stratified analysis revealed that among non-gastric primary tumor patients with c-Kit exon 11 mutations, partial response on imaging, or postoperative imatinib ≤24 months, the intermediate-term group had significantly better RFS and OS than the short-term group (all P<0.05), but had no differences compared to the long-term group (P>0.05). Multivariate Cox regression analysis indicated that preoperative imatinib duration was not an independent factor for RFS (P>0.05), but treatment for 7-12 months was an independent protective factor for OS (HR=0.275, 95% CI: 0.089-0.851, P=0.025), while prolonging therapy beyond 12 months conferred no additional OS benefit (P>0.05). Conclusions: In patients with locally advanced GIST, preoperative imatinib therapy for 7-12 months yielded the most favorable prognosis, with significantly improved RFS and OS compared to ≤6 months of treatment. Extending preoperative therapy beyond 12 months did not provide additional survival benefit.