Contemporary Patterns and Survival Outcome of Adjuvant Systemic Therapy for Localized Gastrointestinal Stromal Tumors

Objectives:To describe contemporary patterns of and factors associated with adjuvant therapy use and survival outcome after resection of localized gastrointestinal stromal tumors (GISTs) using a large contemporary clinical database.Methods:We queried the National Cancer Data Base to identify localized GIST cases diagnosed from 2004 to 2011, and used descriptive and logistic regression analyses to determine patterns of and factors associated with adjuvant therapy. Kaplan-Meier and Cox proportional-hazard model were utilized to generate survival probabilities and hazard ratios (HRs).Results:Of 4694 patients, 73.5% received surgery alone, and 26.5% received adjuvant therapy during 2004 to 2011. Receipt of adjuvant therapy more than doubled between 2006 (13.2%) and 2007 (30.5%), peaked to 37.9% in 2009, and then decreased to 25.6% in 2011 (P for trend<0.0001). Receipt of adjuvant therapy monotonically decreased with older age (P for trend<0.0001), and was higher in patients with larger tumor size (>10 cm) than those with smaller tumor size (5 cm) (44.1% vs. 15.8%; P<0.0001). Patients who received adjuvant therapy had 46% lower risk of death than those who received surgery alone (HR=0.55; 95% confidence interval, 0.37-0.79; P<0.001); survival benefit was statistically significant for GISTs with >10 cm tumor size (HR=0.42; 95% confidence interval, 0.20-0.89; P=0.02).Conclusions:In a large nationwide dataset, we showed that the use of adjuvant therapy for localized GISTs has significantly increased over time and patients treated with adjuvant therapy have better survival than patients treated with surgery alone.