Please see the next post for the calculations I ran. This is admittedly a crude analysis, but I think it's accurate enough for the purposes of this discussion.
Proportion of Phase-2 Cancer Trials That Are RCT’s
Using the advanced search tool at www.clinicaltrials.gov, I searched for interventional studies whose indication was cancer, carcinoma, adenoma, leukemia, or lymphoma. To find all such trials with a given phase, the Search Term field was left blank (first column in the table below); to find the randomized subset of such trials for a given phase, the Search Term field was set to “randomized” (second column in the table below).
To exclude trials that are randomized but not controlled (e.g. trials with randomization to multiple doses of the same treatment regimen), the Search Term field was set to “randomized AND uncontrolled” (third column in table below). The number of randomized controlled trials for a given phase, shown in the fourth (rightmost) column of the table, was determined by subtracting the third column from the second column.*
To exclude phase-1/2 trials, I subtracted the number of trials returned by the search query when checking the “Phase I” box from the number of trials returned by the search query when checking the “Phase I” and “Phase II” boxes. The result of this subtraction, shown in the third row of the table below, is the number of phase-2 trials not designated as phase-1/2.
The number of interest is the result of dividing the fourth column of the third row by the first column of the third row: 2169 / 8973 = 24.2%.
Randmzd Randmzd All Randmzd Uncntrld Contrld PhaseStudiesStudiesStudiesStudies I,II,I/II 14,597 2,885 212 2,673 Less I,I/II 5,624 561 57 504 ============== ====== ===== === ===== II (excl I/II) 8,973 2,324 155 2,169
*Some randomized trials in the clinicaltrials.gov database are not designated as either “controlled” or “uncontrolled”; I included these trials because the vast majority of them have an active or placebo control arm.