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.