• cancer imaging;
  • clinical trials;
  • imaging biomarkers;
  • quantitative imaging;
  • tumour volume;
  • volumetry

Serial evaluations of tumour burden using imaging, mainly computed tomography and magnetic resonance imaging, form the basis for assessing treatment response in many clinical trials of anticancer therapeutics. Traditionally, these evaluations have been based on linear measurements of tumour size. Such measurements have limitations related to variability in technical factors, tumour morphology and reader decisions. Measurements of entire tumour volumes may overcome some of the limitations of linear tumour measurements, improving our ability to detect small changes reliably and increasing statistical power per subject in a trial. Certain technical factors are known to affect the accuracy and precision of volume measurements, and work is in progress to define these factors more thoroughly and to qualify tumour volume as a biomarker for the purposes of drug development.