Synthesis: TNBC clinical trial participation barriers

Evidence grades (GRADE-adapted): A high — multiple well-conducted RCTs or systematic reviews converge. B moderate — single pivotal RCT or consistent observational evidence. C limited — single observational study, mechanistic, or expert consensus. D preclinical / hypothesis-generating.

Trial enrollment landscape

Approximately 5% of US adult cancer patients enroll in therapeutic clinical trials — a rate that has been remarkably stable for decades despite multiple interventions to increase enrollment^[1]A. Specific TNBC observations:

• Pivotal trials (KEYNOTE-522, ASCENT, DESTINY-Breast04, OlympiAD, EMBRACA) all have substantially under-representative Black enrollment relative to disease burden
• Hispanic enrollment is also under-representative in most pivotal trials
• Asian-American enrollment varies but is often below population representation
• Lower-income participants are systematically underrepresented
• Geographic clustering of enrollment at academic centers means rural patients have limited access
• AYA enrollment patterns vary by trial

Structural barriers

Eligibility criteria

Restrictive eligibility criteria exclude many patients who could potentially benefit:

• Performance status requirements (ECOG 0–1) exclude patients with significant comorbidity
• Organ function thresholds (creatinine, bilirubin, transaminases) exclude patients with subclinical organ impairment
• Prior treatment exclusions limit trial access for patients in later treatment lines
• Brain metastases exclusions (relevant for TNBC given CNS predisposition) limit eligibility for many trials
• HIV-positive, hepatitis B/C-positive exclusions historically common; increasingly being relaxed
• Autoimmune disease exclusions for IO trials exclude many patients
• Age limits (older or younger) exclude relevant patient populations
• Pregnancy and contraception requirements pose barriers

ASCO/Friends of Cancer Research initiative on broadening eligibility criteria has produced recommendations for criteria liberalization that maintain safety while expanding access^[2]B. Implementation in TNBC trials is increasing.

Geographic access

Trial sites are concentrated at NCI-designated cancer centers and large academic medical centers:

• ~75% of trial enrollment occurs at academic centers
• Patients living far from these centers have limited access
• Rural patients face especially significant access barriers
• Community oncology practices have low rates of trial offering
• Even within academic centers, satellite clinics may have limited trial offering

Financial barriers

Trial participation involves direct and indirect costs:

• Routine care costs during trial participation may not be covered
• Travel and lodging for trial visits create financial burden
• Time off work for trial visits is often unpaid
• Childcare during trial visits creates additional costs
• Lost productivity affects family income

The Affordable Care Act requires insurance coverage of routine costs during trial participation, but implementation is uneven; Medicaid coverage varies by state.

Patient-side barriers

Awareness and information

• Many patients are unaware of trials as a treatment option
• Information about specific trials is hard to navigate (ClinicalTrials.gov is difficult for lay users)
• Decision-support tools to help patients understand trial options are limited
• Discussion of trials in clinical encounters varies by provider and practice

Trust and historical context

• Historical research ethics violations (Tuskegee, Henrietta Lacks, others) contribute to legitimate mistrust in some communities
• Ongoing concerns about research treatment of underserved populations
• Concerns about being "used" or treated as a "guinea pig"
• Trust in specific institutions or providers may be more important than general trust in research

Time and burden

• Trial visits require time commitment substantially beyond standard care
• Travel time can be substantial for patients far from trial sites
• Compounding work, family, and care responsibilities
• Some trial designs (intensive PK sampling, multiple imaging studies) particularly burdensome

Language and cultural barriers

• Trial materials often only in English
• Informed consent processes may be challenging for non-native speakers
• Cultural preferences around medical decision-making may differ
• Interpreters may not be reliably available

Provider-side barriers

• Awareness of available trials — oncologists in community practice may have limited awareness of relevant trials
• Referral patterns — referral to academic centers for trial enrollment varies by community oncologist
• Time pressure — discussing trial options requires substantial encounter time
• Reimbursement — trial enrollment activity is not separately reimbursed in most contexts
• Implicit bias — documented in some studies suggesting unconscious patient selection patterns may contribute to enrollment disparities
• Investigator workforce diversity — clinical trial investigators are predominantly White; concordant investigator-patient demographics correlate with enrollment patterns

Documented enrollment disparities

Multiple analyses document trial enrollment disparities:

• Race/ethnicity — Black, Hispanic, Asian, and Native American enrollment underrepresentative
• Insurance status — uninsured and Medicaid-insured patients have lower trial participation
• Income — lower-income patients enroll at lower rates
• Education — higher educational attainment correlates with trial enrollment
• Age — older patients are underrepresented in pivotal trials
• Rural residence — rural patients have lower enrollment
• Comorbidity burden — patients with significant comorbidity are excluded by eligibility criteria

In TNBC specifically, the underrepresentation is particularly consequential because the underrepresented populations have the highest disease burden.

Interventions to expand trial access

FDA Diversity Action Plans

FDA guidance now requires sponsors to submit Diversity Action Plans for pivotal clinical trials, addressing recruitment strategies to enrolll patients from historically underrepresented groups. Impact on TNBC trial enrollment is being tracked.

Decentralized and hybrid trial designs

• Decentralized trials use telehealth, mobile clinical research professionals, home health nursing, and electronic data capture to reduce in-person site visit requirements
• Hybrid designs combine in-person and remote elements
• Direct-to-patient drug delivery reduces site-visit requirements
• Wearable and remote monitoring reduce assessment burden
• COVID-19 pandemic accelerated decentralized trial adoption; longer-term integration is being formalized

Community-based recruitment

• Community-academic partnerships — NCI Community Oncology Research Program (NCORP) brings trials to community settings
• Faith-based and community organization partnerships — outreach through existing community networks
• Patient navigation — trained navigators help patients consider and access trial enrollment
• Cultural broker programs — bilingual, bicultural patient liaisons

Eligibility criteria broadening

• ASCO/Friends of Cancer Research recommendations on broadening eligibility
• FDA guidance on inclusion of patients with brain metastases, organ dysfunction, HIV
• Sponsor-side adoption of broader criteria is increasing

Financial support for participation

• Lazarex Cancer Foundation and similar organizations provide travel/lodging support
• 21st Century Cures Act allows sponsor reimbursement of patient costs without anti-kickback concerns
• Trial-specific financial support programs are increasingly common

Master protocols and shared infrastructure

• I-SPY 2 platform — shared neoadjuvant trial infrastructure across multiple academic centers
• NCI-MATCH and successor protocols — basket trials accommodate multiple cancer types
• Master protocols reduce per-trial infrastructure burden

Evidence table

Open questions and active investigation

• Long-term FDA Diversity Action Plan impact. Whether the recent FDA guidance produces sustained improvements in trial diversity is being tracked.
• Decentralized trial outcomes equivalence. Whether outcomes from decentralized trials are equivalent to traditional site-based trials remains a methodological question; specific examples are accumulating.
• Effective navigation program design. Patient navigation can improve trial enrollment; cost-effective scalable models are being identified.
• Community-academic partnership impact. NCORP and similar partnerships have improved community-setting trial access; further expansion is being studied.
• AI and matching tools. AI-based trial-matching tools can identify eligible trials for patients more efficiently than manual review; clinical impact is being evaluated.
• Trust-building in historically underserved communities. Sustained community engagement, transparent communication, and accountability for research practices are needed.
• Investigator diversity initiatives. Increasing diversity in the clinical trial investigator workforce may contribute to enrollment diversity over time.

For socioeconomic determinants that intersect with trial participation, see the socioeconomic synthesis. For ancestry-driven disparities, see the ancestry disparities synthesis. For shared decision-making about trial participation, see the shared decision-making synthesis.

References

Each citation links to the original publication via DOI. The same records are searchable in the evidence library by title or DOI.

1. Unger JM, Cook E, Tai E, Bleyer A. The Role of Clinical Trial Participation in Cancer Research: Barriers, Evidence, and Strategies. Am Soc Clin Oncol Educ Book. 2016;35:185–198. doi:10.1200/EDBK_156686. ↩
2. Kim ES, Bruinooge SS, Roberts S, et al. Broadening Eligibility Criteria to Make Clinical Trials More Representative: American Society of Clinical Oncology and Friends of Cancer Research Joint Research Statement. J Clin Oncol. 2017;35(33):3737–3744. doi:10.1200/JCO.2017.73.7916. ↩
3. Duma N, Vera Aguilera J, Paludo J, et al. Representation of Minorities and Women in Oncology Clinical Trials: Review of the Past 14 Years. J Oncol Pract. 2018;14(1):e1–e10. doi:10.1200/JOP.2017.025288. ↩

Last reviewed: 2026-06-04. Researcher-layer synthesis page. Evidence grades follow the GRADE-adapted rubric defined at the top of this page.