OBJECTIVETo evaluate the recurrence-free survival (RFS) and safety of imatinib adjuvant therapy with longer treatment duration in patients undergoing complete resection of localized primary gastrointestinal stromal tumor (GIST).

METHODSClinical and follow-up data of 101 GIST patients between March 2004 and May 2009 with intermediate or high recurrence risk receiving imatinib adjuvant treatment and more than 3 years follow-up time in Peking University Cancer Hospital were retrospectively analyzed. Imatinib adjuvant treatment: 3 patients discontinued less than 1 year imatinib treatment because of adverse events; 24, 21 and 18 patients discontinued imatinib after 1 year, 2 years, and 3 years treatment; 8 patients received 3 years adjuvant treatment and were ongoing; 27 patients received more than 4 years imatinib adjuvant treatment.

RESULTSThe median follow-up time was 60 months (95%CI:57.9-62.1). Nineteen patients had GIST recurrence, of whom recurrence happened during imatinib adjuvant therapy in 5 patients and after imatinib treatment in 14 patients. The median period from imatinib stopping to recurrence was 12.0 months (95%CI:9.6-14.4). Patients with recurrent GIST achieved tumor control after imatinib resumption. RFS of patients (n=53) with ≥3 years imatinib treatment duration was higher than that of patients (n=48) with <3 years imatinib duration (93.9% vs. 68.0%, P<0.01). In addition, prolonged adjuvant imatinib duration did not significantly increase the adverse events related to treatment (P>0.05).

CONCLUSIONSProlonged adjuvant imatinib duration may further improve RFS rate further in patients with intermediate or high risk of recurrence after complete tumor resection without increased adverse events.