In a 10-year follow-up of the phase III SSGXVIII/AIO trial reported in JAMA Oncology, Heikki Joensuu, MD, and colleagues found that 3 years vs 1 year of adjuvant treatment with imatinib was associated with superior overall survival among patients with high-risk gastrointestinal stromal tumors.
Heikki Joensuu, MD
The investigators stated, “Adjuvant imatinib is associated with improved recurrence-free survival when administered after surgery to patients with operable gastrointestinal stromal tumors, but its influence on overall survival has remained uncertain.”
In the trial, 400 patients from sites in Finland, Germany, Norway, and Sweden who had undergone macroscopically complete surgery were randomly assigned between February 2004 and September 2008 to receive imatinib at 400 mg/d for 12 months or 36 months. The intention-to-treat cohort consisted of 397 patients, including 199 in the 12-month group and 198 in the 36-month group.
Median follow-up was 119 months.
For the 36-month group vs the 12-month group, recurrence-free survival was 71.4% vs 53.0% at 5 years and 52.5% vs 41.8% at 10 years (hazard ratio [HR] = 0.66, 95% confidence interval [CI] = 0.49–0.87, P = .003).
For the 36-month group vs the 12-month group, overall survival was 92.0% vs 85.5% at 5 years and 79.0% vs 65.3% at 10 years (HR = 0.55, 95% CI = 0.37–0.83, P = .004).
In an efficacy population excluding 15 patients who did not have gastrointestinal stromal tumors at central pathology review and 24 who had intra-abdominal metastases removed at surgery, 10-year overall survival was 81.6% vs 66.8% (HR = 0.50, 95% CI = 0.32–0.80, P = .003).
An exploratory analysis among 81 patients in the 36-month group and 94 patients in the 12-month group with disease recurrence showed similar median overall survival after recurrence (6.4 vs 6.7 years, HR = 1.00, P > .99).
Cancer other than gastrointestinal stromal tumors was diagnosed in 17.2% of patients in the 36-month group and 12.1% of patients in the 12-month group, with the most common being prostate cancer (7 patients in each group). Death from cancer other than gastrointestinal stromal tumors occurred in 4.0% and 3.5% of patients. No new safety signals were detected.
The investigators concluded, “Three years of adjuvant imatinib is superior in efficacy compared with 1 year of imatinib. Approximately 50% of deaths may be avoided during the first 10 years of follow-up after surgery with longer adjuvant imatinib treatment.”
Dr. Joensuu, of Helsinki University Hospital, University of Helsinki, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was funded by Novartis Oncology, Cancer Society of Finland, and others. For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.