Long-Term Imatinib Treatment for Patients with Unresectable or Recurrent Gastrointestinal Stromal Tumors.

Background: Only limited data are available concerning the long-term outcomes of imatinib treatment among Japanese or Asian patients with advanced or recurrent gastrointestinal stromal tumors (GIST). Our multicenter study, which was conducted in northern Kanto, Japan, aimed to assess the efficacy of imatinib mesylate against advanced or recurrent GIST.

Summary: The clinicopathological data of 234 GIST patients who were treated at one of the 11 participating hospitals from 2001 to 2011 were retrospectively reviewed (GREAT study). Imatinib was administered as a first-line therapy in cases involving unresectable disease or postoperative recurrence (41 cases). The patients treated with imatinib (n = 41) exhibited 1-, 3-, and 5-year overall survival (OS) rates of 92.3, 74.9, and 53.8% respectively. In univariate and multivariate analyses, imatinib continuation with dose reduction and achieving a complete or partial response were found to be associated with increased OS. The results of 2 large-scale, long-term trials demonstrate that the risk of tumor progression decreases with increased treatment duration. Furthermore, the interruption of imatinib treatment in responsive and controlled patients results in a high risk of disease progression. Key Messages: Long-term imatinib treatment is recommended for patients with nonprogressive disease. If patients experience significant toxicities, temporary dose reduction and treatment continuation might be useful.