Is three years duration of adjuvant imatinib mesylate treatment sufficient for patients with high-risk gastrointestinal stromal tumor? A study based on long-term follow-up.

Abstract

130 Background: The therapy for gastrointestinal stromal tumors (GIST) has changed significantly since the use of Imatinib Mesylate (IM). However, the appropriate duration of receiving adjuvant IM for patients with high-risk GIST who underwent R0 resection is still controversial. Methods: From Jan. 2005 to Dec. 2014, 234 patients who underwent R0 resection and were treated with adjuvant IM were identified from a database. The effect of the medication duration on the long-term outcomes was analyzed. Results: In this study, the 5 year recurrence-free survival (RFS) rate and overall survival (OS) rate in the whole groups were 76.2% and 83.4%, respectively. The patient's prognosis was improved due to the prolongation of the time of receiving the Imatinib treatment (P < 0.05). According to the risk stratification analysis, the survival of the moderate-risk patients who received IM adjuvant therapy for 1 year, 1-3 years and more than 3 years showed improved, but the difference was not statistically significant (P > 0.05). However, in the high-risk patients, the RFS rates of the 1 year group, 1-3 years group, 3-5 years group and more than 5 years group were 36.5%, 68.7%, 71.2% and 90.8%, respectively, and the OS rates were 36.7%,76.6%, 84.0% and 97.4%, respectively (P < 0.001). Additionally, linear regression analysis showed that the long-term outcomes of patients with high-risk GIST significantly improved due to prolonged adjuvant IM treatment durations (P < 0.05). The RFS rate of patients receiving IM more than 5 years was significantly better than those receiving it for less than 5 years. Multivariate analysis in the patients with high-risk GIST showed that tumor located in small intestine was an independent risk factor, while receiving IM treatment was an independent protective factor for prognosis. Conclusions: The long-term outcomes of patients with high risk GIST improved due to the prolongation of the IM treatment. To reduce the recurrence and improve the long-term survival, we suggest that patients with high-risk GIST receive Imatinib treatment for at least 5 years.