Real-world data on the efficacy and safety of adjuvant chemotherapy in Japanese patients with a high-risk of gastrointestinal stromal tumor recurrence

Background: Complete surgical resection is the only treatment for resectable gastrointestinal stromal tumors (GISTs). Three-year adjuvant chemotherapy (AC) is recommended for patients with high-risk GISTs. However, there are scarce data on this topic in Japan. We aimed to study the efficacy and safety of AC in Japanese patients with high-risk GISTs.

Methods: Patients with high-risk GISTs who received complete resections during 1992-2019 in our hospitals were included in this retrospective study. We evaluated patients' treatments with or without AC, completion rates, adverse events (AEs), recurrence-free survival (RFS), and overall survival (OS).

Results: Overall, 89 patients categorized as high risk were enrolled in this study. Fifty-five patients received AC (AC group), and 34 patients did not receive AC (control group). Twenty-three (41.8%) patients experienced Common Terminology Criteria for Adverse Events Grade 2 or higher AEs. At a median follow-up of 61.6 months, 41 (74.5%) patients completed the planned treatment (including six patients with ongoing treatment), whereas 14 (25.4%) patients did not complete the treatment owing to the development of AEs (nine patients), patients' request (three patients), recurrence (one patient), and mutational analysis (one patient). Comparing the data between the treatment and control groups, the RFS rate was significantly better for the AC group (P < 0.001). However, there was no significant difference in the OS rate between the two groups.

Conclusion: Postoperative AC was well tolerated by Japanese patients at an acceptable rate, and its use may reduce the risk of recurrence in patients with high-risk GISTs.