Fewer children enrolling in cancer clinical trials, study shows
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Enrollment of children in cancer clinical trials historically has been much more robust than that of adults and has driven significant improvements in the treatment of pediatric cancers.
However, a study by researchers at University of Colorado Cancer Center showed declining rates of enrollment in Children’s Oncology Group (COG) trials.
The researchers estimated pediatric cancer cases from 2004 to 2015 using the SEER database and compared the totals with clinical trial enrollment data from COG, the largest pediatric oncology group. They found enrollment decreased from 40% to 70% in studies completed during the 1990s to 20% to 25% in the early 2000s and 19.9% in the current study.
According to Kelly Faulk, MD, University of Colorado Cancer Center investigator and pediatric oncologist at Children’s Hospital Colorado, these findings are not altogether negative.
“Good treatments have been developed for some of our most common childhood cancers, such as acute lymphoblastic leukemia,” Faulk said in an interview with Healio. “ALL has seen dramatic improvements in outcomes over the past several decades, to the point that a certain subset of these patients has OS rates of 90% to 95%. So, to ask a study question that we could answer becomes a lot harder; we would need thousands and thousands of patients to feasibly show improvement above that 95% OS rate.”
Faulk discussed other potential reasons for declining pediatric trial enrollment and suggested ways to bolster enrollment among this population.
Question: What prompted you to conduct this study?
Answer: Pediatric trial enrollment has not been evaluated in a while. It’s been an evolving research landscape within pediatric oncology. There have been prior reports of disparities in outcomes by race or ethnicity. We know that kids generally do better when they’re enrolled in a cancer trial. For all those reasons, we thought it was important that we continue to examine how we’re doing.
Q: How did you conduct the study?
A: We used the SEER database to estimate the number of U.S. cancer cases among patients aged zero to 29 years between 2004 and 2015. We compared that with a COG database of all patients who enrolled on upfront cancer clinical trials during the same period. We determined how representative the enrolled cohort was by comparing different demographic and socioeconomic factors.
Q: Pediatric cancers generally do not have as many targetable mutations. Given the current focus on personalized medicine, might this be a factor in low trial enrollment?
A: We need to consider that. The move to personalized medicine has happened later in pediatrics and we are still learning its utility in kids. Commonly, these innovations trickle down from the adult side to pediatrics. COG did not have a huge number of trials that were molecularly characterized during the time period evaluated, where a genetic mutation makes the patient eligible rather than the histologic diagnosis. However, things are moving that way, so over the next 10 years, this might play a big role in enrollment rates.
Q: What other factors might be involved in the decrease in pediatric cancer trial enrollment? Are patients and families being adequately informed of this option?
A: It doesn’t feel as though our culture within pediatric oncology has changed in the sense of prioritizing enrollment for our patients. It may be more related to the fact that we are not able to offer an available trial to every patient. We investigated trial availability in the paper by broadly assessing how many trials were open for each diagnosis during that time period, although this is of course only a surrogate for whether a trial was truly available to any given patient, because trials open and close frequently, some sites might not have had a particular trial open, or a patient may have not been eligible. There are many reasons why a trial might seem to be available for a patient, but turns out not to be. It’s a difficult thing to study.
Q: Are there any subgroups of children with especially low enrollment?
A: We wanted to highlight the adolescent and young adult (AYA) population. This population historically has had very poor enrollment rates on clinical trials, and we confirmed that again with this study. We were looking only at COG trial enrollment, and many AYA patients are not treated at pediatric institutions, so there are some methodologic limitations, but we answered the question of how COG is doing with adolescent and young adult enrollment. AYAs are a difficult population in that they span both pediatric and adult oncology practices, so their treatment and trial options likely vary depending on where they’re treated. Other factors often are involved in this population, as well, such as lack of good health insurance and the difficult nature of making independent health care decisions about trial enrollment. COG has done a lot of work to increase the age-eligibility limits on its trials to target this population. It also has done a lot of work to advocate for the cooperative group to globally reduce its lower age limit to include our patients. I’m hoping this will continue.
Another thing I found interesting and great was that there was minimal disparity based on racial ethnicity or socioeconomic factors. A good deal of the adult literature that has listed enrollment rates shows disparities among ethnicities and those of lower socioeconomic status. I think this really emphasizes the wide reach of COG. I hope it means that we, and they, are doing a really good job of enrolling representative populations.
For more information:
Kelly Faulk, MD, can be reached at kelly.faulk@childrenscolorado.org
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