Tumor volume as an alternative response measurement for imatinib treated GIST patients

PLoS One. 2012;7(11):e48372. doi: 10.1371/journal.pone.0048372. Epub 2012 Nov 2.


Background: Assessment 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).

Methods: LM 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.

Results: 3D 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.

Conclusion: Volume 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.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents / pharmacology
  • Automation
  • Benzamides / pharmacology*
  • Cohort Studies
  • Disease Progression
  • Female
  • Gastrointestinal Neoplasms / drug therapy*
  • Gastrointestinal Stromal Tumors / drug therapy*
  • Humans
  • Imaging, Three-Dimensional
  • Imatinib Mesylate
  • Male
  • Medical Oncology / methods
  • Middle Aged
  • Neoplasm Metastasis
  • Observer Variation
  • Piperazines / pharmacology*
  • Pyrimidines / pharmacology*
  • Time Factors
  • Tomography, X-Ray Computed / methods
  • Treatment Outcome


  • Antineoplastic Agents
  • Benzamides
  • Piperazines
  • Pyrimidines
  • Imatinib Mesylate

Grants and funding

The authors have no support or funding to report.