Who Gets Into Cancer Trials: Participation, Who Is Missing and the Global Gap

In the United States, about 8 in every 100 people with cancer assessed in the studies pooled by one major review joined a treatment trial. For most of the rest, the barrier was not a decision they made: either no trial was open where they were treated, or the trial that was open excluded them. The people who do take part are, on average, younger than the people who get cancer, and Black and Hispanic people are a fraction of the share their cancer rates would predict.

Clinical trials are where the evidence for tomorrow's cancer care is made. When trials mostly recruit people who are younger, fitter, live near a large teaching hospital and come from one part of the world, the evidence describes those people best. Everyone else is then treated on results drawn from a population that may not look like them. This article sets out, at population level, how many people with cancer take part in trials, who is missing, where the trials are, and what regulators and health systems have said should change. It does not discuss any individual trial or whether any one person should take part.

Fewer than 1 in 10 take part, and most never have a trial to say yes to

The most-cited estimate of how many people with cancer join treatment trials comes from a 2019 meta-analysis by Joseph Unger and colleagues. It pooled 13 US studies, nine in academic centres and four in community settings, covering 8,883 people with cancer who were assessed for trial participation. The denominator matters: these were people being treated at institutions that took part in the studies, not every adult with cancer in the country. Of them, 8.1% enrolled (95% confidence interval 6.3% to 10.0%)^[1].

What makes the review useful is that it follows everyone else too. For 55.6% of people, no trial was available at their institution for their cancer. A further 21.5% were ineligible for the trial that was available, and 14.8% were eligible but did not enrol. Enrolment was 15.9% in academic settings against 7.0% in community settings, but the rates of trial unavailability, ineligibility and non-enrolment did not differ between them. The authors conclude that structural and clinical barriers together make "trial participation unachievable for more than three of four cancer patients"^[1]. The common assumption that people with cancer are reluctant to take part does not survive this data: the larger share of the gap sits with where trials are opened and who they are designed to include.

England: research is discussed with fewer than half

England does not publish a national rate of trial enrolment among all people with cancer, and we could not verify a cancer-specific recruitment figure for 2024/25 from NIHR at source (see How to read this data). The best population-level window is the National Cancer Patient Experience Survey. Its 2025 round surveyed adults with a confirmed primary cancer treated as inpatients or day cases in NHS trusts in April to June 2025; 64,268 of 134,285 people responded (48%)^[4]. Of those who answered the research question, 45.5% said research opportunities they could take part in had been discussed with them, similar to 45.8% in 2024 and up from 44.1% in 2021^[4]. The survey counts any research, including tissue donation, extra scans and sharing data, so it measures whether any research was raised, not trial enrolment.

An earlier analysis of the same survey, published in 2015 and covering 66,953 people, found that 30.4% reported discussions about research and 18.9% took part in research of any kind. Staff were less likely to discuss research with older people, and Asian and Black respondents were less likely to take part^[5]. The questionnaire was redeveloped in 2021, so these older figures cannot be read as a trend alongside the current series.

In the four most common cancers, trial participants are six and a half years younger than the people who get them

Cancer is mostly diagnosed in later life, but the evidence base is built largely on younger people. A 2019 study in JAMA Oncology examined 302 phase 3 randomised trials in the four most common cancers (breast, prostate, bowel and lung), which together enrolled 262,354 people. Compared with the population median age at diagnosis for the same cancer in the United States, the median age of trial participants was on average 6.49 years younger^[6].

The gap was wider in industry-funded trials, which made up 82.5% of the sample (an average of 6.84 years younger, against 4.72 years in other trials), and it was getting wider over time, by about 0.19 years each year^[6]. More recent data point the same way. In 329 pivotal trials behind US Food and Drug Administration (FDA) cancer drug approvals from January 2018 to November 2024, adults aged 65 and over were enrolled at 0.86 times the rate their share of US cancer diagnoses would predict. In trials whose enrolment midpoint fell in the pandemic years 2020-2022, the median ratio for this age group was 0.64, against 0.76 in other trials, a borderline difference (P=0.05)^[2].

When the people in trials are younger than the people who receive the treatment, the trial results say less about how treatments work for the older majority. The wider picture of cancer care in later life, including under-treatment and geriatric assessment, is covered in Older people with cancer.

Black people with cancer make up about a quarter of the share of approval-trial participants their diagnoses would predict

The clearest US evidence on ethnicity comes from the trials that regulators use to approve new cancer medicines. Looking at 230 trials (112,293 participants) behind FDA cancer drug approvals from July 2008 to June 2018, Loree and colleagues found that only 63.0% reported the race of participants at all. Where it was reported, White people made up 76.3% of participants, Asian people 18.3%, Black people 3.1% and Hispanic people 6.1%. Measured against each group's share of US cancer incidence, Black people were enrolled at 22% of the expected level and Hispanic people at 44%, against 98% for White people and 438% for Asian people^[7]. Many approval trials also recruit outside the US, so a US incidence comparator is approximate.

The newer analysis of 2018-2024 approvals uses the same logic, an enrolment-incidence ratio against SEER data. Black participants had a pooled ratio of 0.26 and Hispanic participants 0.50, while White participants were proportionally represented (0.97). The share of Black participants moved only from 2.7% in 2019 to 3.6% in 2023, and the authors found no significant improvement for Black or Hispanic participants over the period^[2].

Who runs the trial makes a difference. Across 358 trials in 15 cancer types over 2008-2018, Black people made up 2.9% of participants in pharmaceutical company-sponsored trials behind FDA approvals and 9.0% in trials run by SWOG, a publicly funded US network, against 12.1% of the US cancer population^[8]. Neither reached parity, but the publicly funded network came much closer. These gaps sit alongside the wider differences in diagnosis and care set out in Ethnicity and cancer. These figures describe whom trials reach and record, not who is willing to take part.

Rural and low-income participants are barely counted, so their gaps are hard to see

Rural residents are not always missing. In 36,995 people enrolled in 44 phase 3 and phase 2/3 SWOG treatment trials across all 50 US states between 1986 and 2012, 19.4% lived in rural areas, and rural participants were well represented across the four major US regions. They were, however, less likely to be Black than urban participants (5.4% against 12.1%)^[9]. That is one publicly funded network over a long period, and its record cannot be assumed for trials in general.

The bigger problem is that most trials do not record these characteristics at all. A 2026 systematic review screened 6,681 trials and examined 441 US-based randomised phase II and III cancer treatment trials published in high-impact journals from 2020 to 2025. Reporting of race or ethnicity had become routine, rising from 62.3% of trials in 2020 to 93.9% in 2025. But no trial reported rurality, income or area deprivation; two reported education and one reported insurance status^[10]. Without those fields, nobody can say from published trials whether people on low incomes or in remote areas are fairly represented. The wider evidence on income, deprivation and cancer outcomes is set out in Deprivation and cancer.

Nine in ten phase 3 cancer trials are led from high-income countries

The geographic gap is starkest at global scale. Wells and colleagues identified every phase 3 randomised trial of cancer treatment published from 2014 to 2017: 694 in all. Of these, 636 (92%) were led from high-income countries and 58 (8%) from low- and middle-income countries^[3]. How cancer outcomes and services differ in those countries is set out in The global cancer gap.

The research agenda follows the funding. Trials led from high-income countries were far more likely to be industry-funded (73% against 41%), and the mix of cancers studied did not match the global toll. Breast cancer accounted for 17% of the trials and 7% of global cancer deaths, while cancers of the stomach and oesophagus accounted for 6% of trials and 14% of deaths, liver cancer 2% of trials and 8% of deaths, and cervical cancer 1% of trials and 3% of deaths^[3]. Trials led from low- and middle-income countries were also smaller (median 219 participants against 474)^[3].

Source: Wells et al., JAMA Oncology, 2021^[3]. Shares of 694 phase 3 randomised trials published 2014-2017, against the share of global cancer deaths the authors used for comparison.

What the evidence asks of us

The figures point less at people with cancer than at the system around them. Where trials are open, who they are designed to include and what they record are choices made by sponsors, funders, regulators and health services. The evidence suggests several of those choices could be made differently.

• Bring trials to where people are treated. For more than half of the people in the US meta-analysis, no trial was open at their institution, and enrolment in community settings was less than half that in academic ones^[1]. Opening trials in community and district hospitals, not only in large centres, addresses the largest single barrier in the data.
• Write eligibility criteria for the people who get the cancer. One in five people in that analysis was ruled out by the criteria of an available trial^[1], and participants in major trials were on average six and a half years younger than the population with the same cancers^[6]. Funders and ethics committees can ask that age limits and exclusions be justified.
• Set and publish enrolment goals. In the US, a 2022 law (section 3602 of FDORA) required the FDA to issue guidance on diversity action plans for clinical studies. That guidance is still a non-binding draft (June 2024), and its web page now carries a notice that it was restored by court order to its January 2025 version^[11]. With no statistically significant improvement for Black or Hispanic participants in approval trials through 2024^[2], that framework needs to be kept and enforced.
• Record who takes part. No recent high-impact US cancer trial in the 2026 review reported rurality, income or deprivation^[10]. Journals and funders could require these fields alongside age and sex, as is now routine for race and ethnicity.
• Fund trials where the deaths are. With 8% of phase 3 cancer trials led from low- and middle-income countries^[3], research capacity there needs sustained investment. The World Health Assembly's 2022 resolution WHA75.8 asked WHO to strengthen clinical trials worldwide, and WHO's 2024 guidance on best practice responds to it^[12].
• Measure the conversation. England's patient survey shows research is discussed with fewer than half of the people treated for cancer^[4]. The survey programme already publishes trust-level results and subgroup comparisons; tracking this question by age, ethnicity and deprivation, trust by trust, would show where opportunities are not reaching people.

For the full picture of cancer evidence on this site, see the Cancer research library.

Language: this piece says "people with cancer" and "people living with and after cancer", and describes the illness and its treatment plainly, without combat metaphors. Clinical terms such as "stage", "incidence" and "net survival" are used in the sense the cited source defines them.

Why we're publishing this

Charities and support groups are often asked why trials seem out of reach for the people they work with. The honest answer from the US evidence is that, for most people assessed, there was no trial to join or the trial that existed was not designed for them. We are publishing these figures so that organisations can make that case to funders, sponsors and regulators with the evidence in hand, and so that the people missing from trials, older people, Black and Hispanic people in the US, rural and low-income communities, and whole regions of the world, are counted rather than assumed away.

How to read this data

Most of the deep evidence here is from the United States, because US trial and registry data are the most extensively analysed; treat it as a worked case, not a global rate. The 8.1% enrolment figure is a pooled estimate from 13 studies of people treated at participating institutions, from studies published before 2019, and not a national population rate. The enrolment-incidence ratios compare trial participants with US cancer incidence from SEER, although many approval trials recruit internationally, so they show direction and scale more than an exact shortfall. The English survey measures whether research was discussed, for any kind of research, among people treated as inpatients or day cases who chose to respond; it is not an enrolment rate, and its questionnaire was redeveloped in 2021. The global figures count where trials were led, not where every participant was enrolled, and the share of global cancer deaths they are set against is the comparator the authors used; the abstract does not give the year of the mortality estimate. We looked for a cancer-specific NIHR recruitment figure for England for 2024/25 and for the FDA's 2024 Drug Trials Snapshots, but could not read them at source, so neither is used.

Use this data

Free to cite with attribution to Better Health For Everyone. Charities, campaigners and journalists are welcome to reuse these figures and charts. For the underlying figures as a spreadsheet, get in touch.

Important: This article summarises published research for general information. It is not medical advice and cannot be used to diagnose, treat or predict anything about an individual. If you have concerns about your own or someone else's health, please speak to a qualified health professional.

Sources

1. Unger JM, et al. Systematic review and meta-analysis of the magnitude of structural, clinical, and physician and patient barriers to cancer clinical trial participation. Journal of the National Cancer Institute, 2019. europepmc.org/article/MED/30856272
2. Cheng H, Li J, Mao N, et al. Equity and representation in oncology clinical evidence for FDA-approved treatments and the impact of COVID-19. Frontiers in Oncology, 2026. frontiersin.org/journals/oncology/articles/10.3389/fonc.2026.1666497
3. Wells JC, Sharma S, Del Paggio JC, et al. An analysis of contemporary oncology randomized clinical trials from low/middle-income vs high-income countries. JAMA Oncology, 2021. europepmc.org/article/MED/33507236
4. NHS England and Picker. National Cancer Patient Experience Survey 2025: national quantitative report. NHS England, 2026. ncpes.co.uk/wp-content/uploads/2026/07/1.1-NCPES25_national-quantitative-report_Final.pdf
5. Mc Grath-Lone L, Day S, Schoenborn C, et al. Exploring research participation among cancer patients: analysis of a national survey and an in-depth interview study. BMC Cancer, 2015. europepmc.org/article/MED/26341736
6. Ludmir EB, Mainwaring W, Lin TA, et al. Factors associated with age disparities among cancer clinical trial participants. JAMA Oncology, 2019. europepmc.org/article/MED/31158272
7. Loree JM, Anand S, Dasari A, et al. Disparity of race reporting and representation in clinical trials leading to cancer drug approvals from 2008 to 2018. JAMA Oncology, 2019. europepmc.org/article/MED/31415071
8. Unger JM, Hershman DL, Osarogiagbon RU, et al. Representativeness of Black patients in cancer clinical trials sponsored by the National Cancer Institute compared with pharmaceutical companies. JNCI Cancer Spectrum, 2020. europepmc.org/article/MED/32704619
9. Unger JM, Moseley A, Symington B, et al. Geographic distribution and survival outcomes for rural patients with cancer treated in clinical trials. JAMA Network Open, 2018. europepmc.org/article/MED/30646114
10. Unger JM, et al. Reporting of rurality, deprivation, and socioeconomic characteristics in cancer clinical trials: a systematic review. JAMA Network Open, 2026. europepmc.org/article/MED/42334847
11. US Food and Drug Administration. Diversity action plans to improve enrollment of participants from underrepresented populations in clinical studies (draft guidance for industry). FDA, 2024. fda.gov/regulatory-information/search-fda-guidance-documents/diversity-action-plans-…
12. World Health Organization. Guidance for best practices for clinical trials. WHO, 2024. who.int/publications/i/item/9789240097711