Incorporation of Adjuvant Therapy into the Multimodality Management of Gastrointestinal Stromal Tumors of the Stomach in the United States

Gastrointestinal stromal tumors (GIST) treatment changed considerably with introduction of imatinib in 2001 and reports of early successes. However, little is known about imatinib incorporation into practice. Our objective was to examine the integration of adjuvant systemic therapy into GIST management. Patients with gastric GIST were identified (n = 4508) from the National Cancer Data Base (2001-2007). Separate regression models were developed to examine factors associated with adjuvant and neoadjuvant therapy use. A total of 3050 patients underwent surgical resection. From 2001-2003 to 2006-2007, use of adjuvant therapy increased from 29 to 47% (P < 0.001). Patients were less likely to receive adjuvant therapy if tumors were < 3 cm, low grade, had negative margins, were treated at low-volume centers, or were diagnosed during 2001-2003 (P < 0.01). Adjuvant systemic therapy for lesions < 3 cm also increased (17 to 25%, P = 0.001). For high-risk GISTs, adjuvant therapy use increased from 41 to 58% overall, with increases of 46 to 70% at high-volume centers and 40 to 48% at low-volume centers (P < 0.001). Neoadjuvant therapy increased from 0 to 8%; patients were more likely to receive neoadjuvant treatment if their tumor was > 6 cm, treated at high-volume centers, or were diagnosed during 2006-2007 (P < 0.001). Adjuvant systemic therapy use for GISTs was increasing and widespread prior to FDA approval of adjuvant imatinib, suggesting that contemporaneous advances in management of advanced GIST were being simultaneously and rapidly translated into the adjuvant setting. As relatively costly therapies are integrated into practice, more robust tracking systems are needed to monitor the incorporation of new treatments.