Neoadjuvant imatinib in patients with locally advanced non metastatic GIST in the prospective BFR14 trial

Background: The role of surgery in the management of patients with advanced gastrointestinal stromal tumors (GIST) in the era of imatinib mesylate (IM) remains debated. We analyzed the outcome of patients with non metastatic locally advanced primary GIST treated with IM within the prospective BFR14 phase III trial. Methods: The database of the BFR14 trial was searched for patients with no metastasis at time of inclusion. Patients treated for recurrent disease were excluded. Twenty-five of 434 patients met these criteria. Results: Fifteen of 25 patients (60%) had a partial response to IM. Nine of the 25 patients (36%) underwent surgical resection of their primary tumor after a median of 7.3 months of IM treatment (range 3.4-12.0). Per protocol patients received continuous IM treatment in the post resection period, in an adjuvant setting. With a median follow-up of 53.5 months, there was a significant improvement in progression-free survival (PFS) and overall survival (OS) for patients who underwent surgical resection versus those who did not (median not reached vs 23.6 months, p = 0.0318 for PFS and median not reached vs 42.2 months, p = 0.0217 for OS). In the group of patients who underwent resection followed by IM, the 3-year PFS and OS rates were 67% and 89% respectively Conclusions: Following neoadjuvant IM for non metastatic locally advanced GIST 9 of 25 patients (36%) were selected for resection of the primary tumor. OS and PFS figures were close to those of localised intermediate or high risk GIST (70% at 5 years) in the subgroup of operated patients, while the outcome of the non-operated subgroup was similar to that of metastatic GIST.