A new symptom measure in gastrointestinal stomal tumors

e17508 Background: Symptom burden is the combined impact of disease- and treatment-related symptoms on daily functioning. A major barrier to effective symptom management in gastrointestinal stromal tumors (GIST) is inadequate assessment. Our aim was to develop a short, valid, reliable patient-reported outcome measure of GIST symptoms for research and practice. Methods: After giving IRB-approved informed consent, 110 patients with GIST completed the 13 symptom severity and 6 interference items of the core MD Anderson Symptom Inventory (MDASI) plus 9 GIST-specific symptom items generated from patient and expert input. Items were measured on a 0-10 scale (0 = none, 10 = worst imaginable). 65 patients completed the same items 1 day later. Patients also answered a single overall quality-of-life (QOL) question. Demographic and disease information was collected on all patients. Psychometric procedures determined reliability and validity of the MDASI-GIST. Results: Mean subject age was 59.2 years (standard deviation [sd] = 11.9). 54% of the subjects were female, 85% were white, 47% were employed, 55% were on imatinib, and 30% had no evidence of disease. Mean overall QOL rating was 8.1 (best = 10, sd = 2.0). Symptoms reported as most severe were fatigue (mean [M] = 2.65, sd = 2.66), drowsiness (M = 2.36, sd = 2.55), disturbed sleep (M = 2.18, sd = 2.55), and muscle soreness/cramping (M = 2.18, sd = 2.67). Two items (abdominal swelling and malaise) were eliminated for redundancy. Internal consistency (Cronbach α) and test-retest reliability of the 20 symptom items were 0.94 and 0.93, respectively, and of the 6 interference items were 0.94 and 0.87, respectively. The mean severity of the 20 symptom items was significantly correlated with QOL rating (correlation = -0.7, P < 0.001). Mean GIST-specific symptom severity and symptom interference discriminated between patients who were employed and patients who were disabled (P = 0.05 and 0.03, respectively). Conclusions: We have validated an analytic tool, the MDASI-GIST, to quantify GIST symptom burden, assess side effects in treatment trials, and monitor symptoms in clinical care. Additional research on the longitudinal symptom burden of GIST, including differences based on type of therapy and response to therapy, is ongoing