Is 3-years duration of adjuvant imatinib mesylate treatment sufficient for patients with high-risk gastrointestinal stromal tumor? A study based on long-term follow-up.

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 January 2005 to December 2014, 234 patients who underwent R0 resection and were treated with adjuvant imatinib at our institution were identified from a prospectively collected database. The effect of the medication duration on the long-term outcomes was analyzed.

RESULTS

In this study, 140 cases were male and 94 cases were female, and the mean age was 57.5 ± 11.4 years. The most common site was the stomach (103 cases, 44%), followed by the small intestine (81 cases, 34.6%). 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 results of the risk stratification analysis, the outcomes of the moderate-risk patients who received IM adjuvant therapy for 1-year group, 1-3 years group and more than 3 years group showed improvement, 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). In addition, 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 for more than 5 years was significantly better than those receiving it for less than 5 years. Multivariate COX regression 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.