Tyrosine Kinase Inhibitors Significantly Improved Survival Outcomes in Patients with Metastatic Gastrointestinal Stromal Tumour: A Multi-Institutional Cohort Study

Background: The real-world impact of tyrosine kinase inhibitors (tkis) in clinical practice for gastrointestinal stromal tumour (gist) has not been extensively reported. We sought to assess how outcomes have changed over the eras and to evaluate the effect of access to imatinib and sunitinib on survival in patients with unresectable or metastatic gist in British Columbia. Methods: Patients with metastatic or unresectable gist were allocated to one of three eras: pre-2002, 2002–2007, and post-2007 based on treatment availability (pre-imatinib, post-imatinib, and post-sunitinib). Overall survival (os) and progression-free survival (pfs) were compared between eras. Univariate and multivariate analyses were performed to determine the effects of tumour, patient, and treatment characteristics on survival outcomes. Results: Of 657 patients diagnosed with gist throughout British Columbia during 1996–2016, 196 had metastatic disease: 23 in the pre-imatinib era, 67 in the post-imatinib era, and 106 in the post-sunitinib era. A significant increase in os, by 53.6 months (p = 0.0007), and pfs, by 29.1 months (p = 0.044), was observed after the introduction of imatinib. The introduction of sunitinib did not significantly affect os or pfs. Conclusions: Implementation of tkis has drastically improved survival outcomes for patients with metastatic gist by up to 4.55 years in the real-world setting. Our study demonstrates that implementation of tkis in clinical practice has outperformed their benefit predicted in clinical trials.