Abstract
BackgroundAssessment of tumor size changes is crucial in clinical trials and patient care. We compared imatinib-induced volume changes of liver metastases (LM) from gastro-intestinal stromal tumors (GIST) to RECIST and Choi criteria and their association with overall survival (OS).MethodsLM from 84 GIST patients (training and validation set) were evaluated using manual and semi-automated Computed Tomography measurements at baseline, after 3, 6 and 12 months of imatinib. The ability of uni-dimensional (1D) and three-dimensional (3D) measurements to detect size changes (increase/decrease) ≥20% was evaluated. Volumetric response cut-offs were derived from minimally relevant changes (+20/−30%) by RECIST, considering lesions as spherical or ellipsoidal.Results3D measurements detected size changes ≥20% more frequently than 1D at every time-point (P≤0.008). 3D and Choi criteria registered more responses than RECIST at 3 and 6 months for 3D-spheres (P≤0.03) and at all time-points for 3D-ellipsoids and Choi criteria (P<0.001). Progressive disease by 3D criteria seems to better correlate to OS at late time-points than other criteria.ConclusionVolume criteria (especially ellipsoids) classify a higher number of patients as imatinib-responders than RECIST. Volume discriminates size changes better than diameter in GIST and constitutes a feasible and robust method to evaluate response and predict patient benefit.
Highlights
Assessing anti-tumor effects of systemic therapy is important to estimate activity of novel therapies in clinical trials, but it is a key element to guide treatment changes in day-today routine cancer care
Derived from the World Health Organization (WHO) criteria, which used the product of perpendicular cross-sectional diameters, Response Evaluation Criteria In Solid Tumors (RECIST) is easier to use in daily clinical practice and is considered appropriate to assess tumor response in solid tumors [2,3]
Requiring that our model provides the same result as RECIST in case tumor changes occur along one and the same axis, we choose the same cut-off criteria, or in other words, the cut-offs for ellipsoidal shapes correspond to 30% (PR) and 20% (PD)
Summary
Assessing anti-tumor effects of systemic therapy is important to estimate activity of novel therapies in clinical trials, but it is a key element to guide treatment changes in day-today routine cancer care. The Response Evaluation Criteria In Solid Tumors (RECIST), created in the late 1990s and updated in 2009, are currently considered as the ‘gold standard’ in most oncology settings [1,2,3]. They are based on uni-dimensional (1D) measurements (maximum diameter of target lesions) and their relative decrease or increase during therapy. We compared imatinib-induced volume changes of liver metastases (LM) from gastro-intestinal stromal tumors (GIST) to RECIST and Choi criteria and their association with overall survival (OS)
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