Physician Underestimation of the Risk of Gastrointestinal Stromal Tumor Recurrence After Resection.

IMPORTANCE: Patients with resectable gastrointestinal stromal tumors (GISTs) might not receive the recommended duration of adjuvant therapy if their risk of recurrence is underestimated, which can have an impact on their recurrence-free survival (RFS). OBJECTIVE: To determine the extent of physician underestimation of risk of recurrence after complete primary GIST resection, the impact of underestimation on planned adjuvant treatment duration, and the association among high-risk patients of planned adjuvant treatment duration and RFS. DESIGN, SETTING, AND PARTICIPANTS: This was a retrospective observational medical record review reported by participating oncologists in 2013. US patients with complete primary GIST resection after 2010 were grouped as underestimated or not if their oncologists' charted risk assessments were lower than assessments based on the Revised National Institutes of Health Consensus Criteria or not. Patients were followed by general community oncologists until death or the end of follow-up. MAIN OUTCOMES AND MEASURES: Fisher exact tests compared planned adjuvant treatment duration between groups. Cox proportional-hazards models estimated the impact of planned adjuvant treatment duration on RFS. RESULTS: A total of 109 oncologists reported information on 506 patients with GIST after primary resection (65.8% were high-risk and 8.7% were intermediate-risk). Physicians underestimated risk for 190 patients (37.5%); 30.1% of tumors with an intermediate-level mitotic count (6-10 per 50 high-powered fields) and an intermediate tumor size (6-10 cm) were correctly recognized as high-risk, as were 7.5% of nongastric tumors with an intermediate-level mitotic count and a tumor size of 2 to 5 cm. A smaller proportion of high-risk patients in the underestimated vs not-underestimated groups had at least 3 years of planned adjuvant therapy (36.1% vs 65.9%; P < .001). Planned adjuvant treatment of at least 3 years vs less than 3 years among high-risk patients conferred a lower hazard of recurrence and/or death (adjusted hazard ratio, 0.29; P < .001; 95% CI, 0.14-0.59). CONCLUSIONS AND RELEVANCE: Overall, physicians tended to underestimate the risk of recurrence for many patients with GIST, especially for patients with tumors of intermediate size, intermediate-level mitotic count, and nongastric location, which had an impact on planned adjuvant therapy duration. Patients with at least 3 years of planned adjuvant treatment had longer RFS. Improved education on postresection risk assessment and risk reduction is needed.

Treatment patterns, prescribing decision drivers, and predictors of complete response following disease recurrence in gastrointestinal stromal tumor patients-a chart extract-based approach.

PURPOSE: The aim of this study was to investigate tumor characteristics, treatment patterns, and outcomes in recurrent KIT + GIST patients treated in a community practice setting. METHODS: An online tool was used to retrieve data on 410 patients treated with adjuvant imatinib mesylate (IM) for primary resectable KIT + GIST, who discontinued, had a recurrence, and then restarted IM or initiated sunitinib. Tumor characteristics at recurrence, treatment patterns, and factors associated with post-recurrence complete response (CR) achievement were analyzed. RESULTS: About 72.7 % of patients did not have surgery post-recurrence as majority of them had unresectable (45 %), metastatic (40 %), or multifocal tumors (62.4 %). Following recurrence, 76.6 % of patients were re-started on IM and 23.4 % on sunitinib; patients were 7.37 times more likely to re-start IM if initial treatment duration was ≤18 months (p < 0.001). Patients were also more likely to re-start IM if recurrence occurred >12 months post-discontinuation, or they had a recurrence inside the GI system, lower or unknown Fletcher risk score at primary diagnosis, or lower mitotic rate, (odds ratio (OR) = 3.54, p < 0.001; OR = 2.64, p = 0.006; OR = 2.55, p = 0.007; and OR = 2.45, p = 0.002, respectively). About 22.4 % achieved CR; patients were more likely to achieve CR if they had unifocal tumor at recurrence, inside the GI system, of ≤2 cm, or had lower mitotic rate (OR = 2.61, p < 0.001; OR = 2.27, p = 0.036; OR = 2.16, p = 0.023, OR = 1.87, p = 0.017, respectively). CONCLUSIONS: IM treatment duration at primary diagnosis, time to develop recurrence after IM discontinuation, tumor location, and mitotic rate at recurrence were the main prescribing decision drivers. Tumor characteristics were the most important factor in achieving CR following c-KIT inhibitor retreatment.

Comparison of the long-term risk of recurrence and other clinical outcomes in GIST patients receiving imatinib as adjuvant therapy--a retrospective chart extract-based approach.

PURPOSE: To compare characteristics of patients, the risk of recurrence, and mortality among adult patients with primary resectable gastrointestinal stromal tumor (GIST) receiving short-term (6-12 months) versus long-term (≥ 24 months) imatinib therapy. METHODS: Detailed information on primary resectable KIT-positive GIST patients initiated on imatinib adjuvant therapy was retrospectively collected for short- and long-term imatinib patients from 318 US oncologists using an online data collection form. Patient characteristics were compared using Wilcoxon and Chi-square tests. Disease recurrence and mortality rates were compared using multivariate Cox proportional hazard models. RESULTS: Among the 406 short-term and 406 long-term imatinib patients, the median follow-up was 916 and 970 days, respectively. While patients generally had similar demographic characteristics, the short-term group had a higher prevalence of cardiovascular and ischemic heart diseases and patients in the long-term group had a higher pre-surgery risk profile. This finding was consistent with the main reason reported by oncologists for prescribing adjuvant imatinib over longer duration, i.e., patient risk profile. Disease recurrence [5.9 versus 1.2 %, (p < .001)] and mortality rates [7.1 % versus 2.0 %, (p < .001)] were higher in short- versus long-term patients. The adjusted risk of recurrence was 5.30 times (p < .001) higher, and mortality risk was 4.02 times (p < .001) higher in short- versus long-term patients. CONCLUSIONS: Patient risk profile is an important factor in oncologists' decisions to prescribe adjuvant imatinib. Despite the higher risk profile observed in long-term patients, the long-term use of imatinib was associated with a reduction in long-term risk of disease recurrence and mortality.