Sixteen uncontrolled phase II studies (1,110 participants) were included in the review: one randomised controlled trial (RCT, 713 participants), three phase II studies (204 participants), three cohort studies (181 participants) and nine case reports (12 participants). The RCT was described by the reviewers as being of good quality, with appropriate randomisation and blinding and use of intention-to-treat analyses. Adequate methods of recruitment were reported in the uncontrolled studies and more than 80% of the participants were included in the follow-up; in these studies it was unclear whether confounding factors were identified by the study authors.
The results of the RCT showed significant benefits of adjuvant treatment with imatinib, with a 65% reduction in the risk of disease recurrence at one year (HR 0.35, 95% CI 0.22 to 0.53) with a NNT of seven patients to prevent one recurrence or death from gastrointestinal stromal tumours. In each tumour size category, recurrence-free survival was higher in the imatinib-treated groups.
No differences in survival were observed between the imatinib-treated group and the placebo-treated group in the RCT. There were significantly larger numbers of early withdrawals from treatment in the imatinib-treated group than the placebo-treated group (16% in the imatinib group compared to 3% in the placebo group, p<0.0001). Withdrawals due to tumour recurrence were higher in the placebo-treated group (12%) compared to the group of patients who received imatinib (<1%). The most common adverse events in the imatinib-treated group were dermatitis, abdominal pain and diarrhoea.
The other studies showed trends towards increased recurrence-free survival in patients treated with adjuvant imatinib therapy.