Abstract:

Objective To analyze the impact of imatinib adjuvant therapy on the postoperative prognosis of patients with non-gastric primary high-risk gastrointestinal stromal tumor （GIST）. Methods A retrospective analysis was conducted on the clinical data， postoperative treatment and survival information of 40 patients with non-gastric primary high-risk GIST admitted to Weihai Municipal Hospital Affiliated to Shandong University from January 1， 2010 to May 30， 2022. All patients underwent radical surgical resection. Patients receiving imatinib （400 mg/d） as adjuvant therapy started taking the medication 4 to 8 weeks after the surgery. Univariate and multivariate analyses of factors influencing patient prognosis were performed using the Cox proportional hazards regression model. Kaplan-Meier survival curves were plotted， and patients were stratified based on whether they completed 3-year or 5-year postoperative imatinib adjuvant therapy. Inter-group comparisons were made using the log-rank test. Results By the end of the follow-up period， among the 40 patients， 37 received adjuvant therapy， of whom 16 experienced tumor progression and 7 of these died due to tumor progression； 3 patients did not receive adjuvant therapy， and 2 of them died due to tumor progression. The 3-， 5-， and 10-year disease-free survival （DFS） rates were 79.1%， 60.0%， and 25.3%， respectively， while the 3-， 5-， and 10-year overall survival （OS） rates were 94.1%， 90.6%， and 54.1%， respectively. Univariate analysis revealed that the Ki-67 （HR=4.01， 95%CI： 1.04-15.27， P=0.048） and imatinib adjuvant therapy （HR=4.59， 95%CI： 1.05-20.23， P=0.041） were factors influencing DFS. Tumor number （HR=5.83， 95%CI： 1.06-21.93， P=0.042） and imatinib adjuvant therapy （HR=5.05， 95%CI： 1.03-24.26， P=0.044） were factors influencing OS. Multivariate analysis identified Ki-67>5% （HR=4.21， 95%CI： 1.03-20.73， P=0.046） and without postoperative imatinib adjuvant therapy （HR=6.23， 95%CI： 1.23-31.59， P=0.027） as independent risk factors for DFS. Multiple tumor numbers （HR=8.77， 95%CI： 1.40-55.01， P=0.020） and not receiving postoperative imatinib adjuvant therapy （HR=7.70， 95%CI： 1.28-46.41， P=0.026） were independent risk factors for OS. The 5-year DFS and OS rates were 46.2% and 90.0% in the group receiving postoperative imatinib adjuvant therapy for less than 3 years， compared to 90.0% and 100.0% in the group receiving therapy for more than 3 years， with statistically significant differences （χ²=8.24， P=0.004； χ²=6.34， P=0.012）. The 5-year DFS and OS rates were 55.0% and 92.2% in the group receiving postoperative imatinib adjuvant therapy for less than 5 years， compared to 100% and 100% in the group receiving therapy for more than 5 years. There was a statistically significant difference in the 5-year DFS rate between the two groups （χ²=3.94， P=0.047）， but no statistically significant difference in the 5-year OS rate （χ²=2.10， P=0.147）. Conclusions Ki-67>5%， multiple tumor numbers and without postoperative imatinib adjuvant therapy are independent risk factors affecting the postoperative prognosis of non-gastric primary high-risk GIST patients. 5-year imatinib adjuvant therapy can prolong the postoperative DFS of non-gastric primary high-risk GIST patients and improve their prognosis.

Key words: Gastrointestinal stromal tumors, Neoadjuvant therapy, Prognosis, Imatinib