Evolution of multimodality management of gastrointestinal stromal tumors of the stomach.

Abstract

94 Background: Gastrointestinal stromal tumor (GIST) treatment has changed considerably with introduction of imatinib in 2001, initiation of ACOSOG adjuvant trial in 2002, and FDA adjuvant approval in 2008. However, little is known about how imatinib has been incorporated over time. Our objective was to examine the evolution of multimodality management of GISTs. Methods: Patients coded specifically as gastric GISTs were identified (n = 4,508; 443 hospitals) from the National Cancer Data Base (2001-2007). Changes over time were assessed with chi-squared test for trend. Separate multivariable regression models were developed to examine factors associated adjuvant and neoadjuvant practices. Results: Gastric GISTs reported to NCDB steadily increased: 463 in 2001 to 831 in 2007. 3,289 underwent resection: 78% partial/wedge, 6% total/near-total, and 14% multivisceral. From 2001 to 2007, use of adjuvant therapy increased from 29% to 47% (p < 0.001), although patients were less likely to get adjuvant therapy if older, tumors < 3cm, low grade, negative margins, or treated at low-volume hospitals (p < 0.01). Adjuvant systemic therapy for lesions < 3 cm also increased (17% to 25%, p = 0.001). For GISTs > 6 cm, use of adjuvant therapy increased from 41% to 49% overall, with increases of 45% to 70% at high-volume centers and of 39% to 48% at low-volume centers (all p < 0.001). Neoadjuvant therapy increased from 0% to 15% (p < 0.001) with patients more likely to receive neoadjuvant treatment if size > 6 cm, treated at high-volume centers, or treated in 2006-2007 (p < 0.001). Multivisceral resections decreased over time (19% to 12%, p < 0.001). The proportion of patients treated at high-volume centers increased slightly over time (22.2% to 26.9%, p = 0.006). Conclusions: Adjuvant systemic therapy use for GISTs was increasing and widespread prior to FDA approval of adjuvant imatinib, suggesting contemporaneous advances in advanced GIST management were being translated into the adjuvant setting more than expected. As relatively costly therapies are integrated into practice, more robust tracking systems are needed to follow and guide the incorporation of new treatments. No significant financial relationships to disclose.