437 Background: Gastrointestinal stromal tumor (GIST) is a visceral sarcoma that arises from the gastrointestinal tract. Currently, imatinib (first-line) and sunitinib (second-line) are two reimbursed targeted therapies for GIST in Taiwan. This study aimed to evaluate the real world data of targeted therapies in GIST treatment among Taiwanese population. Methods: We conducted a nationwide retrospective cohort study based on data from the National Health Insurance Research Database (NHIRD) between January 2005 and December 2010. NHIRD is a comprehensive database of administrative and claim data which covers over 99% of entire population in Taiwan. Patients were selected with ICD codes and targeted therapy utilization, imatinib (IMA) or sunitinib (SUN). Time to treatment discontinuation (DC) due to any reasons (such as death, intolerance and disease progression) was estimated using Kaplan-Meier analysis. Results: From 2005 to 2010, the incidence rate of GIST in Taiwan was between 20 and 30 cases per million. A total of 3,436 GIST patients were identified; the mean age was 63.2 years and 57 % were male. Most patients (94.7%) received standard dose IMA (…400mg/day). Among these patients, 136 patients (4.0%) required IMA dose escalation and 44 (1.3%) patients switched to SUN after IMA. The probability of the 1st-line treatment DC was 20%, 30.7%, 38.9%, 43.2%, and 47.1% for years 1 to 5, respectively. The probability of a change in treatment pattern (defined as either IMA dose escalation or switch to SUN) was 4% 6.8%, 9.6%, 10.5% and 11.7% for years 1 to 5. Lastly, the probability of the 2nd-line treatment DC was 20.5%, 33.7%, 41.1%, 44.8%, 51.7% for years 1 to 5, respectively. Conclusions: First-line IMA plus other treatment modalities may provide additional benefits to progression-free survival. Taiwanese GIST patients who failed first-line treatment still gained benefit from either IMA dose escalation or a switch to SUN. Additional analysis is required for the detailed comparison in different treatment patterns.
1635P Clinical and pathologic prognostic factors for residual lesion surgery following disease control with standard dose imatinib (IM) in patients (pts) with advanced gastrointestinal stromal tumor (GIST)
