Prognostic factors for metastatic gastrointestinal stromal tumors treated with cytoreductive surgery: a retrospective cohort study.

Background: Cytoreductive surgery (CRS) may benefit patients with metastatic gastrointestinal stromal tumors (GISTs) treated with tyrosine kinase inhibitors (TKIs). However, there is insufficient evidence on prognostic factors for metastatic GISTs undergoing CRS.

Methods: This study reviewed metastatic GISTs that underwent CRS after receiving TKIs in our center from April 2014 to December 2023. We collected clinicopathologic characteristics and survival data for analyses via the Cox hazard model and Kaplan-Meier method.

Results: Finally, 73 patients with metastatic GISTs who underwent CRS were enrolled. The TKI treatments used at time of surgery were imatinib (n = 53, 72.6%) and subsequent-line TKIs (n = 20, 27.4%). There were 30 patients (41.1%) with responsive disease (RD), 17 patients (23.3%) with unifocal progression disease (UP) and 26 patients (35.6%) with multifocal progression disease (MP) to TKIs at the time of surgery. The median follow-up time was 31 months. Multivariate Cox analysis revealed that MP (HR 2.406, p = 0.025), R2 resection (HR 2.532, p = 0.023), and mitotic index ≥5/50 HPFs (high-power fields) (HR 2.687, p = 0.022) independently predicted worse progression-free survival (PFS), and R2 resection predicted worse overall survival (OS) (HR 5.202, p = 0.039) for the entire cohort. In the subgroup analysis, radiographic response, extent of resection and mitotic index were prognostic factors for patients receiving imatinib but not those receiving subsequent-line TKIs. The rate of postoperative complications was 9.6% and the rate of grade III or higher complications was 4.1%.

Conclusions: Non-MP, R0/1 resection and mitotic index < 5/50 HPFs may predict better outcomes for patients with metastatic GISTs on imatinib, and CRS is feasible and safe.