Optimal Duration of Imatinib Mesylate Therapy in Metastatic Gastrointestinal Stromal Tumours

While current literature provides evidence that imatinib mesylate has significant activity in patients with advanced and metastatic gastrointestinal stromal tumour (GIST), and highlights the potential for the development of anticancer drugs based on specific molecular abnormalities present in cancers, specific recommendations concerning the optimal duration of therapy remain controversial. This case presents the favourable outcome of a patient who originally presented almost 9 years ago with widespread, bulky, metastatic GIST involving the abdomen and pelvis. A sustained, complete response was achieved with imatinib and prompted an interruption in treatment 7 years after initial presentation. The disease reoccurred extensively within 9 months of treatment interruption, but once again rapidly completely responded to the recommencement of imatinib, with that response being now maintained for over 9 months. This report suggests that dramatic and durable responses to imatinib can be achieved in individual cases despite the lack of specific guidelines in the literature with respect to defining how long treatment with imatinib should be continued in the absence of evidence of tumour progression.