Newly developed prognostic maps that can assess the likelihood that a gastrointestinal stromal tumor (GIST) will recur following surgery will better determine high-risk patients who are most likely to benefit from additional therapy. Such information could reduce overtreatment of low-risk persons while identifying high-risk candidates for aggressive treatment.

A team led by Professor Heikki Joensuu, MD, from Helsinki University Central Hospital in Helsinki, Finland, assessed key prognostic factors for recurrence-free survival among 2,560 people with operable GIST who did not receive adjuvant therapy. They then stratified recurrence risk according to three widely used risk-prediction methods, and used their findings to develop a new method for estimating the risk of GIST recurrence.

Joensuu’s group learned that surgery alone cured more than half the patients (59.9%), making adjuvant therapy unnecessary. The three risk-stratification models were found to predict 10-year risk of GIST recurrence fairly accurately. Patient data showed that large tumor size, high mitosis count, nongastric location of tumor, presence of rupture, and male sex were independent adverse prognostic factors.

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Because tumor size and mitosis count had a nonlinear association with the risk of GIST recurrence, the researchers generated new prognostic maps to more accurately portray the continuous and nonlinear nature of these variables. The maps also took into account tumor site and rupture.

The maps resulting from this nonlinear model provided the most accurate prognosis for individual GIST patients compared with the conventional models that stratified patients into a few broad groups, concluded the investigators in The Lancet Oncology.