Three Years of Adjuvant Imatinib Better Than One for High-risk GIST, Study Suggests

Three years of adjuvant imatinib therapy results in longer survival than 1 year of imatinib in patients with high-risk gastrointestinal stromal tumors (GISTs), a new study published online ahead of print in the Journal of Clinical Oncology has shown.¹

GISTs are an uncommon type of sarcoma that develop in the connective tissue of the stomach, small intestine, or esophagus. The American Cancer Society estimates that about 4,000 to 5,000 new cases of GIST are diagnosed in the United States each year.²

Because 3 years of adjuvant imatinib therapy are recommended for patients with GIST with high-risk features, researchers led by Heikki Joensuu, MD, of the Comprehensive Cancer Center Helsinki and University of Helsinki in Finland, sought to evaluate whether the survival benefits of 3-year imatinib therapy have persisted in the Scandinavian Sarcoma Group XVIII/AIO trial.

For the study, researchers enrolled 400 patients with macroscopically completely excised, KIT-positive GIST with a high risk for recurrence. After undergoing surgery, participants were randomly assigned to receive adjuvant imatinib for 1 or 3 years.

Results showed that the 5-year recurrence-free survival was 71.1% for the 3-year group compared with 52.3% for the 1-year group (HR, 0.60; 95% CI, 0.44 – 0.81; P < .001). The survival rate was 91.9% vs 85.3%, respectively (HR, 0.60; 95% CI, 0.37 – 0.97; P = .036).

Researchers found that participants with centrally confirmed GIST and without macroscopic metastases at study entry particularly benefitted from 3-year imatinib therapy, as those in the 3-year group had a survival rate of 93.4% compared with 86.6% in the 1-year group (HR, 0.53; 95% CI, 0.30 – 0.93; P = .024).

In regard to safety, a similar number of cardiac events and second cancers were reported in both treatment arms.

“High 5-year survival rates are achievable in patient populations with high-risk GIST,” the authors concluded.

Reference

1. Joensuu H, Eriksson M, Sundby Hall K, et al. Adjuvant imatinib for high-risk GI stromal tumor: analysis of a randomized trial [published online ahead of print November 2, 2015]. J Clin Oncol. doi: 10.1200/JCO.2015.62.9170.
2. What are the key statistics about gastrointestinal stromal tumors? American Cancer Society website. May 9, 2014. http://www.cancer.org/cancer/gastrointestinalstromaltumogastr/detailedguide/gastrointestinal-stromal-tumor-key-statistics. Accessed November 3, 2015.