The impact of age and other factors on enrollment status in cancer clinical trials was assessed for a study that compared adolescents and young adults, or AYAs.

Cancer remains the leading cause of disease-related death in the United States for adolescents and young adults (AYAs) aged 15-39. Despite impressive survival gains achieved in both younger and older populations over the past 30 years, however, AYAs have not experienced the same improvements.

Additionally, while poor enrollment of AYAs into cancer clinical trials (CCTs) may contribute to inferior survival gains compared with children, numerous studies of CCT enrollment indicate that 40% to 60% of children younger than 15 participate in CCTs, compared with only 10% to 20% of early adolescents and young adults (eAYAs) aged 15-21.


Assessing Enrollment

To better address how this age group is treated, Stefanie Thomas, MD, and colleagues conducted a prospective, observational cohort study—published in Cancer—to assess whether differences in CCT availability would explain lower CCT enrollment for eAYAs than older patients with cancer.

The researchers studied consecutive patients who were newly diagnosed with cancer over 13 months, determining whether an appropriate CCT existed nationally or was available locally, as well as whether enrollment in that CCT occurred. The proportions of eAYAs compared with children in each category were assessed using the chi-square test. The impact of age and other factors on enrollment status was assessed using logistic regression analysis.

“There has been a lot of discussion in the adolescent and young adult oncology field, and it is such a small, specific population,” says Dr. Thomas. “A landmark study (conducted by theNational Cancer Institute in 2006) assessed survival rates for this patient population, and they appeared to have worse survival than other populations in terms of changes in survival improvement from the 1970s until the modern era. Older and younger populations were seeing a bit of survival improvement with advances in technology, but the teenager/young adult population wasn’t.”

Among participants who were observed in the study, 26.9% were eAYAs, and 73.1% were children. Of those, 113 (52%) had a trial that existed for them nationally (Table). There was no difference in the proportion of eAYAs compared with children who had an existing CCT (48.3% of eAYAs vs 53.8% of children) or an available CCT (39.7% of eAYAs vs 47.5% of children). However, significantly fewer eAYAs were enrolled when a CCT was available (30.4% of eAYAs vs 67.7% of children).

Upon multivariable analysis, eAYAs were found to be significantly less likely than children to be enrolled in an available CCT. Dr. Thomas says these numbers reveal that—for eAYAs—factors other than CCT availability are important enrollment barriers and should be addressed.


Examining Barriers

“Getting patients to trials or getting trials to patients is always going to be the first step,” says Dr. Thomas. “If patients are treated where there aren’t any trials, then physicians there can’t do anything. It starts with funneling these teenagers and young adults into places with clinical trials. Clinicians should try talking to patients and their families in a developmentally appropriate way so the patients can make informed decisions.”

So why are so few of these patients enrolled in cancer clinical trials?

Dr. Thomas points to biology of disease, insurance and medications, and access to care as barriers to eAYAs enrolling in cancer clinical trials. Other research has shown that decreases in survival improvement occurred simultaneously with decreases in enrollment in clinical trials. However, Dr. Thomas adds that more research is needed to expand upon these speculations and findings.

“Research is ongoing to determine both patient-perceived and provider-level barriers, as well as institutional barriers to open more appropriate trials to patients” says Dr. Thomas.


Thomas, S. M., Malvar, J., Tran, et al. A prospective, observational cohort study comparing cancer clinical trial availability and enrollment between early adolescents/young adults and children. Cancer. 2018;124(5):983-990.. Available at: