BACKGROUNDTo assess the response and the impact on the overall survival (OS) on c-KIT-positive (CD117+) gastrointestinal stromal tumours (GISTs) patients treated with imatinib mesylate.METHODSBetween July 2003 and December 2012, consenting patients with advanced c-kit-positive GISTs were enrolled to receive imatinib mesylate therapy at a dose of 400mg - 800mg daily, supplied gratis by Novartis Pharma (Basel, Switzerland) under its GIPAP initiative. Disease severity was based on tumour site, size and mitotic index at diagnosis. Clinical features together with drug toxicity, haematological and biochemical parameters were monitored. Overall survival (OS) reviewed at 12 months intervals over 5 years was computed using Kaplan-MeierRESULTSThere were 27 patients in all (17 males and 10 females with a median age of 52 years (range 26 - 83). Twenty three patients, 15 males and 8 females that have been followed up for at least 6 months were evaluated, aged 26-83 years (median = 56). There were 17 (73.9%) gastric tumours and 6 extragastric including 3 cases of peritoneum and 1 each of small gut, colon and rectum. At diagnosis, 21 (91.3%) cases were high risk, and 1 each fell into the intermediate and low risks, respectively. Ten patients (43.4%) including 5 with metastases presented with unresectable lesions. Five patients (21.7%) had complete tumour resection, 5 (3 with metastases) had partial resections and 3 others with non-bulky, nonmetastatic diseases underwent no surgery. Imatinib was used as the primary therapy for all patients, except the 5 patients that underwent complete tumour resection. Nine (39.1%) patients were lost to disease progression with a median survival of 16.7 +/- 10.7 (+/- SE) (95% CI = 0-37.6) months. The overall survival at 2 years for all patients was 71.9%, which dropped to 65.9% at 4 years.CONCLUSIONSAlthough a small number of GISTs, imatinib induced an extended remission in patients with advanced disease, most of whom would have been dead within a few months of diagnosis.