One in four cancer trials fails to enroll enough participants

University of Washington researchers developed an algorithm to aid in the design and prioritization of clinical trials.

By Stephen Feller

SEATTLE, Dec. 30 (UPI) -- In order for clinical trials to be worth the time and money, researchers must enroll enough participants to fairly judge the effects of treatments.

Nearly a quarter of trials for cancer drugs, however, fail to enroll enough people for reliability, representing a waste of what researchers in a new study say are limited human and economic resources.


To combat the problem, researchers at the University of Washington designed an algorithm based on a review of trials conducted in the last few years, according to a study published in the Journal of the National Cancer Institute.

"It seems to me that we need to focus on a much more creative strategy than merely trying to avoid the initiation of trials with risk factors that portend failure to complete," wrote Derek Raghavan, a researcher at the Levine Cancer Institute, in an editorial published alongside the study in the Journal of the National Cancer Institute. "It is well documented that patients on clinical trials have better outcomes than those who do not participate. Nonetheless, as oncologists who wish the best for our patients, we should strive to improve trial enrollment, giving the associated potential for improved results."


Researchers reviewed data from 787 studies conducted between 2000 and 2011, focusing on 46 conducted between 2012 and 2013, using them to identify predictors for study candidates.

Of the studies reviewed, 18 percent of of the trials closed with a low accrual of participants, or less than 50 percent of the target participant number three years or more after their start, although 65 percent of trials reviewed for the study had met their goals by the time the researchers conducted their analysis.

Using 13 predictors for accrual of participants -- number of competing trials, phase of trial, enrollment as percentage of eligible population, targeted therapy, radiation therapy, tissue sample requirement, investigational new drug, metastatic setting, sample size, more than one condition evaluated, common solid cancer, and interaction term -- the researchers created an algorithm predicting how a study may fare in its recruitment efforts.

Researchers note that over time many trials appeared to meet participant goals, making it possible that trials used to conduct the study will eventually accrue their desired number of patients. They also note that using an algorithm to determine whether enough participants will be recruited should not replace judgement calls on the feasibility or usefulness of a trial, though it may aid in decision-making.


"We identified multiple characteristics of cooperative group-sponsored trials that were importantly not associated with low accrual, several of which have not been previously empirically described," the researchers wrote. "Systematically considering the overall influence of these factors could aid in the design and prioritization of future clinical trials and therefore provides a direct response to the Institute of Medicine's call for efforts to improve the selection, support, and completion of publicly funded cancer clinical trials."

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