The following article features coverage from the 2021 ASCO Quality Care Symposium. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Despite efforts to increase enrollment in adult cancer trials and data suggesting that most patients are willing to participate, the rate of enrollment is estimated to be less than 5%.1,2,3

However, a contemporary examination of a large national database indicates that adult participation in cancer research is higher than that.

These data were presented at the American Society of Clinical Oncology (ASCO) Quality Care Symposium 2021 by Joseph Unger, PhD, of Fred Hutchinson Cancer Research Center in Seattle.4

Continue Reading

Dr Unger noted that prior surveys of trial participation among adult cancer patients are nearly 2 decades old. Furthermore, those surveys were focused solely on enrollment to treatment trials and failed to reflect patients’ contributions to other categories of clinical research, including quality of life, cancer prevention, and biorepository studies.

With this in mind, Dr Unger and Mark Fleury, PhD, of the American Cancer Society Cancer Action Network in Washington, DC, examined a sample of institution-level data from 1200 centers accredited by the American College of Surgeon’s Commission on Cancer (CoC).

The CoC provides accreditation for both academic and community cancer care facilities and has a database of about 70% of all cancer cases diagnosed in the United States annually. Through its accreditation process, the CoC reviews information from one-third of its member programs each year, including clinical trial enrollment from the preceding 3 years.

Dr Unger and Dr Fleury received complete CoC data spanning the period from 2016 through 2018, which provided enrollment data for the period from 2013 through 2017.

The data consist of deidentified, institution-level aggregate counts of annual enrollment to treatment, biorepository, diagnostic, economic, genetic, quality of life, and registry studies for adults with cancer.

The researchers used multiple imputation by chained equations to account for missing data and calculated summary estimates of trial enrollment.

The institutions providing enrollment information included comprehensive community cancer programs (75.7%), comprehensive academic cancer centers (15%), integrated network cancer programs (5.8%), and comprehensive cancer centers with National Cancer Institute (NCI) designation (3.6%).


The participation estimates for all studies ranged from a low of 23.3% to a high of 46.2%. In other words, at least 23.3% of patients were estimated to have participated in 1 or more study type. 

Dr Unger said there were meaningful rates of participation across all study types. Specifically, 6.3% of patients were enrolled in treatment trials, 3.6% were enrolled in genetic studies, 2.9% were enrolled in quality of life studies, and 2.7% each were enrolled in diagnostic and economic studies.

However, the greatest proportion of patients were enrolled in biorepository studies (13.4%) and registry studies (8.1%). 

When the researchers excluded biorepository and registry studies, 16.2% to 27% of patients participated in cancer trials.

Enrollment for different types of studies varied by type of institution. However, participation was consistently — and sometimes dramatically — highest at NCI-designated cancer centers for all study types.

For example, 18.9% of patients at NCI-designated centers participated in treatment trials, compared with 3.9% of patients from community cancer programs, 4.7% from integrated network cancer programs, and 5.0% from academic comprehensive cancer programs.

Significance and Limitations

Dr Unger and colleagues previously showed that, for more than 3 of 4 cancer patients, structural and clinical barriers — such as clinic access, trial availability, and eligibility restrictions — precluded them from considering trial participation.5

The current study demonstrated that, when adult cancer patients were given the opportunity to participate, 6.3% of patients enrolled in cancer treatment trials, and an even higher percentage participated in other study types. 

Overall, nearly 25% of patients enrolled in a cancer trial during 2013-2017.

In comparison with adults, pediatric cancer patients have historically been regarded as participating in clinical trials at a higher rate. When paired with recent declining accrual trends for children and adolescents with cancer,6 the current research suggests the gap between pediatric and adult cancer patients may not be as wide as previously estimated.

During the discussion session, Dr Unger commented that pediatric cancer research participation estimates have traditionally included the broad range of clinical trials employed in the current CoC data analysis.

Dr Unger acknowledged limitations in the current report. For example, the aggregated nature of the data did not allow for important demographic factors to be examined (eg, age, sex, and race). In addition, missing data required the use of imputation methods to complete the participation estimates.

Those limitations notwithstanding, in an era in which biospecimens, clinical genetics, economic, and symptom-control research play an increasingly important role in understanding cancer biology and personalizing therapeutics, adult patients’ contributions to cancer research are much more comprehensive than previously understood.

Disclosures: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of ASCO QCS 2021 by visiting the conference page.


1. Institute of Medicine (US) Committee on Cancer Clinical Trials and the NCI Cooperative Group Program. A national cancer clinical trials system for the 21st century: Reinvigorating the NCI Cooperative Group Program. Washington, DC: National Academies Press; 2010.

2. Tejeda HA, Green SB, Trimble EL, et al. Representation of African-Americans, Hispanics, and Whites in National Cancer Institute cancer treatment trials. J Natl Cancer Inst. 1996;88(12):812-6. doi:10.1093/jnci/88.12.812

3. Unger JM, Hershman DL, Till C, et al. “When offered to participate”: A systematic review and meta-analysis of patient agreement to participate in cancer clinical trials. J Natl Cancer Inst. 2021;113(3):244-257. doi:10.1093/jnci/djaa155

4. Unger JM, Fleury M. Nationally representative estimates of the participation of cancer patients in clinical research studies according to the commission on cancer. J Clin Oncol. 2021 (suppl 28; abstr 74). doi:10.1200/JCO.2020.39.28_suppl.74

5. Unger JM, Vaidya R, Hershman D, et al. Systematic review and meta-analysis of the magnitude of structural, clinical and physician and patient barriers to cancer clinical trial participation. J Natl Cancer Inst. 2019;111(3):245-255. doi:10.1093/jnci/djy221

6. Faulk KE, Anderson-Mellies A, Cockburn M, Green AL. Assessment of enrollment characteristics for Children’s Oncology Group (COG) upfront therapeutic clinical trials 2004-2015PLoS One. 2020;15(4):e0230824. doi:10.1371/journal.pone.0230824