Table 1.

Description of explored tumor size- and CTC-related predictors.

PredictorDerivationTime-varying?Explored as a predictor of:
Tumor size-related
Progressive disease, based on observed tumor size20% and at least 5 mm increase in tumor sizeYesDropout
Normalized baseline tumor size 1Embedded Image NoDropout, CTC, OS
Normalized baseline tumor size 2Embedded Image NoCTC
Absolute tumor time-courseEmbedded Image YesDropout, CTC, OS
Relative change from baseline SLD(t)Embedded Image YesDropout, CTC, OS
Baseline normalized SLD(t)Embedded Image YesCTC, OS
Relative change from lowest SLD(t)Embedded Image YesCTC, OS
Time-course of rate of tumor size changesEmbedded Image YesCTC, OS
Categorical effect (before/after regrowth)NoCTC
Tumor size ratio at week 9Time <9 weeks:Yes (until week 9)OS
Embedded Image
Time ≥9 weeks:
Embedded Image
Tumor size ratio at week 18Time <18 weeks:Yes (until week 18)OS
Embedded Image
Time ≥18 weeks:
Embedded Image
Time to tumor growth, TTGTime <TTG: TimeYes (until time of regrowth)OS
Time ≥TTG: TTG
CTC-related
Absolute mean CTC count, λCTC(t)YesOS
Relative change from baseline λCTC(t)Embedded Image YesOS
λCTC(t) at weeks 1, 3, and 6 (λCTC,1w, λCTC,3w and λCTC,6w)Time <1/3/6 weeks:Yes (until week 1/3/6)OS
Embedded Image
Time ≥1/3/6 weeks:
Embedded Image
λCTC(t) ratio at weeks 1, 3, and 6Time <1/3/6 weeks:Yes (until week 1/3/6)OS
Embedded Image
Time ≥1/3/6 weeks:
Embedded Image
Categorical effect for λCTC(t) ≥1/2/3/estimatedYesOS
  • Abbreviations: BTS, baseline tumor size; SLD0, estimated baseline SLD; SLDmin, lowest SLD; CTCactual,0, estimated baseline mean CTC count given a patient's baseline tumor size.