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GIST recurrence risk often underestimated by physicians
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Clinicians frequently underestimated the recurrence risk for patients with gastrointestinal stromal tumors, according to study results.
Study results also showed fewer patients with an underestimated recurrence risk received 3 years of adjuvant treatment, which appeared associated with longer RFS.
“Gastrointestinal stromal tumors (GISTs) are the most common primary mesenchymal tumors of the gastrointestinal tract, most often occurring in the stomach and small intestines,” Annie Guérin, MSc, vice president of Analysis Group Inc. in Montreal, and colleagues wrote. “In patients with primary resectable GISTs, tumor resection is the mainstay of treatment. However, even after complete resection, recurrence is common, and more than 50% of patients at high risk [for] recurrence develop recurrent and/or metastatic disease within 5 years without adjuvant therapy.”
The National Comprehensive Cancer Network recommends adjuvant imatinib (Gleevec, Novartis) for at least 36 months following resection for patients at high risk for recurrence. However, patients may not receive the complete recommended duration of adjuvant therapy if clinicians underestimate their risk for recurrence.
Guérin and colleagues conducted a retrospective observational review of medical records reported by 109 participating U.S. oncologists. The study included data from 506 patients with GIST after primary resection (median age, 59 years; 54.9% men).
The researchers classified patient risk as underestimated based on whether oncologists’ charted risk assessments were lower than assessments based on the Revised NIH Consensus Criteria.
Median follow-up was 15 months (interquartile range, 10-25) after primary GIST resection.
Based on the Revised NIH Consensus Criteria, 68.5% of patients faced a high risk for recurrence, 8.7% faced an intermediate risk, 10.5% were at low risk and 15% were at very low risk.
Clinicians underestimated the risk for recurrence in 37.5% (n = 190) of patients, overestimated the risk in 9.1% of patients (n = 46) and consistently estimated the risk in 53.4% of patients (n = 270). Overall, researchers observed a moderate agreement between the physicians’ risk assessment and the Revised NIH Consensus Criteria (weighted ĸ = 0.53).
Fewer patients with underestimated risk had a gastric tumor (30% vs. 49.7%), whereas more underestimated patients had a tumor size of 6 cm to 10 cm (46.8% vs. 27.8%) and a mitotic count of 6 to 10 per 50 high-powered fields (64.7% vs. 22.8%; P ˂ .001 for all) than patients whose risk was not underestimated.
A smaller proportion of high-risk patients in the underestimated group received at least 3 years of adjuvant therapy than patients in the non-underestimated group (36.1% vs. 65.9%; P < .001). However, planned adjuvant therapy for at least 3 years conferred a longer HR for recurrence or death among high-risk patients compared with therapy for fewer than 3 years (adjusted HR = 0.29; 95% CI, 0.14-0.59).
The researchers acknowledged that the use of the Revised NIH Consensus Criteria may lead to possible misclassification bias.
“To our knowledge, this is the first study to assess the extent of risk underestimation and its impact on treatment and clinical outcomes,” the researchers concluded. “These findings suggest a need for improved education for physicians on risk assessment and risk reduction.”
It remains important to accurately identify patients who may not benefit from adjuvant therapy following GIST resection, Heikki Joensuu, MD, of the department of oncology at Helsinki University Hospital, wrote in an accompanying editorial.
“As risk underestimation, risk overestimation may also be harmful,” Joensuu wrote. “Approximately 60% of patients with operable GIST are cured by surgery, and the administration of adjuvant imatinib to such patients results in adverse events and costs without proven benefits.” – by Cameron Kelsall
Disclosure: Guérin reports an employment role with Analysis Group Inc. and consultant fees from Novartis related to her employment. Other researchers report employment and consultant roles with and stock ownership in Novartis. Joensuu reports no relevant financial disclosures.
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